apl. Prof. Dr. Sabine Hunke
Profil
Zusammenfassung
Sabine Hunke erforscht, wie Bakterien ihre Zellhülle wahrnehmen und auf Stress reagieren – insbesondere durch spezielle Signalsysteme und Transportmechanismen in der Membran. Sie kombiniert biochemische Laborexperimente mit strukturellen Analysen, um zu verstehen, wie Bakterien Umweltveränderungen erkennen und darauf antworten. Diese Erkenntnisse sind relevant für die Entwicklung von Antibiotika und für das Verständnis von Bakterienvirulenz.
Skills
Stammdaten
Identität, Organisation und Kontakt aus HU-FIS.
Forschungsthemen3
Doctoral Scholarships from Jameel Education Foundation 17th Cohort
Quelle ↗Förderer: Andere internationale Stiftungen Zeitraum: 03/2023 - 12/2027 Projektleitung: Dr. Andrea George, Jeannette Latino, apl. Prof. Dr. Sabine Hunke
Doctoral Scholarships from Jameel Education Foundation 18th Cohort
Quelle ↗Förderer: Andere internationale Stiftungen Zeitraum: 03/2024 - 05/2028 Projektleitung: Dr. Andrea George, apl. Prof. Dr. Sabine Hunke, Jeannette Latino
Doctoral Scolarships from Jameel Education Foundation 19th Cohort
Quelle ↗Förderer: Andere internationale Stiftungen Zeitraum: 06/2026 - 05/2030 Projektleitung: Dr. Andrea George, apl. Prof. Dr. Sabine Hunke, Jeannette Latino
Mögliche Industrie-Partner130
Details nur für eingeloggte sichtbar
🔒 Das System hat 130 mögliche Industrie-Partner gefunden — Firmen, Scores und Begründungen sind nur für eingeloggte Nutzer:innen sichtbar. Anmelden
Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
FEMS Microbiology Reviews · 512 Zitationen · DOI
Members of the superfamily of adenosine triphosphate (ATP)-binding-cassette (ABC) transport systems couple the hydrolysis of ATP to the translocation of solutes across a biological membrane. Recognized by their common modular organization and two sequence motifs that constitute a nucleotide binding fold, ABC transporters are widespread among all living organisms. They accomplish not only the uptake of nutrients in bacteria but are involved in diverse processes, such as signal transduction, protein secretion, drug and antibiotic resistance, antigen presentation, bacterial pathogenesis and sporulation. Moreover, some human inheritable diseases, like cystic fibrosis, adrenoleukodystrophy and Stargardt's disease are caused by defective ABC transport systems. Thus, albeit of major significance, details of the molecular mechanism by which these systems exert their functions are still poorly understood. In this review, recent data concerning the properties and putative role of the ATP-hydrolyzing subunits/domains are summarized and compared between bacterial and eukaryotic systems.
FEMS Microbiology Letters · 124 Zitationen · DOI
The Cpx-envelope stress system coordinates the expression and assembly of surface structures important for the virulence of Gram-negative pathogenic bacteria. It is comprised of the membrane-anchored sensor kinase CpxA, the cytosolic response regulator CpxR and the accessory protein CpxP. Characteristic of the group of two-component systems, the Cpx system responds to a broad range of stimuli including pH, salt, metals, lipids and misfolded proteins that cause perturbation in the envelope. Moreover, the Cpx system has been linked to inter-kingdom signalling and bacterial cell death. However, although signal specificity has been assumed, for most signals the mechanism of signal integration is not understood. Recent structural and functional studies provide the first insights into how CpxP inhibits CpxA and serves as sensor for misfolded pilus subunits, pH and salt. Here, we summarize and reflect on the current knowledge on signal integration by the Cpx-envelope stress system.
Journal of Biological Chemistry · 113 Zitationen · DOI
In Escherichia coli the Cpx sensor regulator system senses different kinds of envelope stress and responds by triggering the expression of periplasmic folding factors and proteases. It consists of the membrane-anchored sensor kinase CpxA, the response regulator CpxR, and the periplasmic protein CpxP. The Cpx pathway is induced in vivo by a variety of signals including pH variation, osmotic stress, and misfolded envelope proteins and is inhibited by overproduced CpxP. Because it is not clear how the Cpx pathway is able to recognize and correspond to so many different signals we overproduced, solubilized, purified, and incorporated the complete membrane-integral CpxA protein into proteoliposomes to analyze its biochemical properties in more detail. Autokinase and phosphotransfer activities of the reconstituted CpxA-His6 protein were stimulated by KCl. NaCl also stimulated the activities but to a lesser extent. Other osmotic active solutes as glycine betaine, sucrose, and proline had no effect. The system was further characterized by testing for susceptibility to sensor kinase inhibitors. Among these, Closantel inhibited the activities of solubilized but not of the reconstituted CpxA-His6 protein. We further analyzed the effect of CpxP on CpxA activities. Purified tagless CpxP protein reduced the phosphorylation status of CpxA to 50% but had no effect on CpxA phosphotransfer or phosphatase activities. As the in vitro system excludes the involvement of other factors our finding is the first biochemical evidence for direct protein-protein interaction between the sensor kinase CpxA and the periplasmic protein CpxP resulting in a down-regulation of the autokinase activity of CpxA. In Escherichia coli the Cpx sensor regulator system senses different kinds of envelope stress and responds by triggering the expression of periplasmic folding factors and proteases. It consists of the membrane-anchored sensor kinase CpxA, the response regulator CpxR, and the periplasmic protein CpxP. The Cpx pathway is induced in vivo by a variety of signals including pH variation, osmotic stress, and misfolded envelope proteins and is inhibited by overproduced CpxP. Because it is not clear how the Cpx pathway is able to recognize and correspond to so many different signals we overproduced, solubilized, purified, and incorporated the complete membrane-integral CpxA protein into proteoliposomes to analyze its biochemical properties in more detail. Autokinase and phosphotransfer activities of the reconstituted CpxA-His6 protein were stimulated by KCl. NaCl also stimulated the activities but to a lesser extent. Other osmotic active solutes as glycine betaine, sucrose, and proline had no effect. The system was further characterized by testing for susceptibility to sensor kinase inhibitors. Among these, Closantel inhibited the activities of solubilized but not of the reconstituted CpxA-His6 protein. We further analyzed the effect of CpxP on CpxA activities. Purified tagless CpxP protein reduced the phosphorylation status of CpxA to 50% but had no effect on CpxA phosphotransfer or phosphatase activities. As the in vitro system excludes the involvement of other factors our finding is the first biochemical evidence for direct protein-protein interaction between the sensor kinase CpxA and the periplasmic protein CpxP resulting in a down-regulation of the autokinase activity of CpxA. The bacterial cell wall is involved in a multitude of diverse structural, physiological, and adaptive processes including transport, elaboration of virulence factors, and cell division. These processes require specific sets of proteins whose correct folding and assembly is controlled by periplasmic folding catalysts and proteases. In Escherichia coli and related species, expression of some of the corresponding genes is regulated by the Cpx sensor regulator system (reviewed in Ref. 1Raivio T.L. Silhavy T.J. Annu. Rev. Microbiol. 2001; 55: 591-624Crossref PubMed Scopus (313) Google Scholar). The Cpx pathway consists of the sensor kinase CpxA, the response regulator CpxR, and the periplasmic CpxP protein (1Raivio T.L. Silhavy T.J. Annu. Rev. Microbiol. 2001; 55: 591-624Crossref PubMed Scopus (313) Google Scholar). The cpxA gene was originally reported as a gene regulating F donor activity in bacterial conjugation (2McEwan J. Silverman P. Proc. Natl. Acad. Sci. U. S. A. 1980; 77: 513-517Crossref PubMed Scopus (54) Google Scholar). It encodes the 52-kDa histidine kinase CpxA, which is an integral membrane protein of the cytoplasmic membrane that contains both periplasmic and cytoplasmic domains (3Weber R.F. Silverman P.J. J. Mol. Biol. 1988; 203: 467-476Crossref PubMed Scopus (71) Google Scholar). The 26-kDa response regulator CpxR is predicted to encode an OmpR-like cytosolic transcriptional activator (4Dong J. Iuchi S. Kwan H.S. Lu Z. Lin E.C. Gene (Amst.). 1993; 136: 227-230Crossref PubMed Scopus (75) Google Scholar). Signals activating the Cpx pathway include elevated pH (5Nakayama S.I. Watanabe H. J. Bacteriol. 1995; 180: 3522-3528Crossref Google Scholar, 6Danese P.N. Silhavy T.J. J. Bacteriol. 1998; 180: 831-839Crossref PubMed Google Scholar), altered membrane composition (7Mileykovskaya E. Dowhan W. J. Bacteriol. 1997; 179: 1029-1034Crossref PubMed Scopus (128) Google Scholar), overproduction of outer membrane lipoproteins such as NlpE (8Snyder W.B. Davis L.J. Danese P.N. Cosma C.L. Silhavy T.J. J. Bacteriol. 1995; 177: 4216-4223Crossref PubMed Scopus (190) Google Scholar), accumulation of misfolded variants of the maltose-binding protein (MBP) 2The abbreviations used are: MBP, maltose-binding protein; Closantel, N-[5-chloro-4-[(R,S)-(4-chlorophenyl)cyanomethyl]-2-methylphenyl]-2-hydroxy-3,5-diodobenzamide; Ethodin, 6,9-diamino-2oxyethyl acridine lactate; LDAO, N,N-dimethyldodecylamine N-oxide; MOPS, 3-(N-morpholino)-propanesulfonic acid; NTA, nitrilotriacetic acid; TCS, 3,3′,4′-5-tetrachlorosalicylanilide; vanadate, Na-orthovanadate-decahydrate. (9Hunke S. Betton J.-M. Mol. Microbiol. 2003; 50: 1579-1589Crossref PubMed Scopus (70) Google Scholar), accumulation of pilus subunits (10Jones C.H. Danese P.N. Pikner J.S. Silhavy T.J. Hultgren S.J. EMBO J. 1997; 21: 6394-6406Crossref Scopus (202) Google Scholar), indole (11Hirakawa H. Inazumi Y. Masaki T. Hirata T. Yamaguchi A. Mol. Microbiol. 2005; 55: 1113-1126Crossref PubMed Scopus (245) Google Scholar), and increasing osmolarity (12Jubelin G. Vianney A. Beloin C. Ghigo J.M. Lazzaroni J.C. Lejeune P. Dorel C. J. Bacteriol. 2005; 187: 2038-2049Crossref PubMed Scopus (209) Google Scholar). The molecular mechanism of signal transduction used by the Cpx sensor regulator system is not clear. CpxA functions as an autokinase, a CpxR kinase, and a CpxR-P phosphatase in vivo (13Raivio T.L. Silhavy T.J. Curr. Opin. Microbiol. 1999; 2: 159-165Crossref PubMed Scopus (155) Google Scholar). CpxA deletion mutants are uninducible, demonstrating that CpxA is necessary for signaling (14Danes P.N. Snyder W.B. Cosma C.L. Davis J.B. Silhavy T.J. Genes Dev. 1995; 9: 387-398Crossref PubMed Scopus (260) Google Scholar). Indeed, cpx* gain of function mutations located in the central region of the periplasmic domain of CpxA are insensitive to normally activating signals and probably define a sensory domain (15Raivio T.L. Silhavy T.J. J. Bacteriol. 1997; 179: 7724-7733Crossref PubMed Scopus (215) Google Scholar). Activation of the Cpx pathway results in increased production of proteins involved in protein folding and degradation in the periplasm, such as the heat shock protease DegP, the peptidyl prolyl cis/trans isomerases PpiA and PpiD, and the disulfide oxidoreductase DsbA (1Raivio T.L. Silhavy T.J. Annu. Rev. Microbiol. 2001; 55: 591-624Crossref PubMed Scopus (313) Google Scholar). In addition, it was shown that CpxR∼P represses motility and chemotaxis genes (16De Wulf P. Kwon O. Lin E.C. J. Bacteriol. 1999; 181: 6772-6778Crossref PubMed Google Scholar). Interestingly, overproduction of the small (19-kDa) periplasmic CpxP protein leads to decreased expression of Cpx-regulated genes and prevents Cpx activation by inducing signals (1Raivio T.L. Silhavy T.J. Annu. Rev. Microbiol. 2001; 55: 591-624Crossref PubMed Scopus (313) Google Scholar). This effect depends on an intact CpxA sensory domain (15Raivio T.L. Silhavy T.J. J. Bacteriol. 1997; 179: 7724-7733Crossref PubMed Scopus (215) Google Scholar). Because an MBP-CpxP fusion was able to inhibit Cpx signal transduction during spheroplast formation, a strong Cpx-inducing signal, it was suggested that the interaction between CpxA and CpxP might be direct (17Raivio T.L. Laird M.W. Joly J.C. Silhavy T.J. Mol. Microbiol. 2000; 37: 1186-1197Crossref PubMed Scopus (83) Google Scholar). On the basis of the observation that the cpx* mutants were constitutively activated (15Raivio T.L. Silhavy T.J. J. Bacteriol. 1997; 179: 7724-7733Crossref PubMed Scopus (215) Google Scholar), it was proposed that the presumed CpxA sensory domain normally functions to maintain the kinase in a down-regulated state mediated by direct interaction with CpxP. When CpxP is titrated out by misfolded envelope proteins, the Cpx response is activated (1Raivio T.L. Silhavy T.J. Annu. Rev. Microbiol. 2001; 55: 591-624Crossref PubMed Scopus (313) Google Scholar, 18Isaac D.D. Pinkner J.S. Hultgren S.C. Silhavy T.J. Proc. Natl. Acad. Sci. U. S. A. 2005; 102: 17775-17779Crossref PubMed Scopus (121) Google Scholar). The finding that the Cpx response can be further activated in a cpxP deletion strain indicates that CpxP is not required for signal transduction (19Raivio T.L. Popkin D.L. Silhavy T.J. J. Bacteriol. 1999; 181: 5263-5272Crossref PubMed Google Scholar), suggesting that CpxP might be responsible for fine-tuning the response. A recent study showed that single amino acid substitutions in a predicted α-helix in the N-terminal domain of the CpxP protein affect its inhibitory function indicating that the N-terminal domain of CpxP is critical for interaction with the sensor CpxA and might be the site of inhibitory activity T.L. J. Bacteriol. 2005; 187: PubMed Scopus Google Scholar). of the on Cpx pathway signal transduction was in we an to and the complete Cpx sensor regulator system into proteoliposomes to study the biochemical properties of the signaling in more detail. This in vitro system was further characterized by testing the effect of of sensor regulator of Yamaguchi Y. J. Biol. 2000; PubMed Scopus Google Scholar). we analyzed the inhibitory effect of the periplasmic CpxP protein on the results first biochemical evidence for a direct protein-protein interaction between CpxA and CpxP resulting in of the CpxA autokinase and were and were was Closantel and were and were and were Purified E. coli were were and were were and and other were and and coli was used as a for the E. coli strain G. J. J. Davis Y. 1997; PubMed Scopus Google was used as strain for the of the and cpxP E. coli strain was used for expression of and cpxP the of the of and of was by the cpxA region and The resulting was into the and of The region was and and into the and of resulting in of was by the cpxP region and The was with and and into the corresponding of The resulting were by of and of and coli strain was with or and with in with and Gene expression was induced with for were and in pH were by on and into membrane and cytosolic The membrane in and the cytosolic were in and of fusion protein was by of in of the protein of cytosolic of was in pH was with an of in were and further with a to the Purified protein was a to and of fusion protein was by of in of the protein of cytosolic was in the of in pH protease with was by increasing the to were a to and further by an was with pH increasing of NaCl with NaCl and into pH by a The the of CpxP was by the as of the were and on for were and of the solubilized proteins were analyzed by The of CpxA-His6 is used as for the of the of CpxA-His6 between the and the membrane of membrane with of was to of membrane were on for and for The solubilized was by with A pH of CpxA-His6 was out by the solubilized and for The was into a and proteins were by with A and CpxA-His6 was by increasing the to were a to and in pH of CpxA-His6 was incorporated into as A. J. Biol. 2001; PubMed Scopus Google Scholar). E. coli were a of and in pH a of CpxA-His6 was of to The was for were in a of and the was were and the was for The was and proteoliposomes were by for The was in pH and The of CpxA into was as the between the of protein in proteoliposomes and in the were used or in proteoliposomes were as but CpxP protein was a to the CpxA with were with a of different the was by and the proteins were to protein of was incorporated into proteoliposomes to for and solubilized CpxA, CpxA in membrane or CpxA in proteoliposomes was with in phosphorylation pH When solutes were different were and with analyze was to were and the was by the of was as with for the phosphorylation was for and was by the of and of of was by the of CpxA-His6 in the were and the was as the signaling in proteoliposomes and CpxR or were in phosphorylation was by the of were and with analyze CpxA-His6 phosphatase activity was were and as were to PubMed Scopus Google Scholar). were and proteins were by a system and as a were in were in pH as Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The phosphorylation were as in the of the inhibitors. the of as a it was also in in an protein were to were and were with to fusion to CpxA-His6 or with to was by the with a or was the protein to the protein of proteins were by and with of the corresponding proteins were used as a on the were with the and protein were with of Cpx of CpxA a was its The activity of the CpxA-His6 protein was to the both autokinase and kinase activities in membrane were in CpxA not CpxA-His6 was used for further in vitro As a for CpxA-His6 by the protein had to be Because the of solubilized CpxA-His6 was to be was used as was used for Interestingly, the different not autokinase activity of the CpxA-His6 not The of CpxA-His6 was the protein was to the in the of and In a of CpxA-His6 was a As by the of CpxA-His6 was CpxR a was its The activity of the protein was to CpxR as it was shown (11Hirakawa H. Inazumi Y. Masaki T. Hirata T. Yamaguchi A. Mol. Microbiol. 2005; 55: 1113-1126Crossref PubMed Scopus (245) Google Scholar). The protein was by the of This protein and the of CpxP we an expression in which the of cpxP corresponding to the signal was by with the protein in different not be in the in a strain not the protein was overproduced and the by the N-terminal histidine were a site resulting in a tagless CpxP protein Purified CpxP an protein with an of protein as the not Because was not in proteoliposomes the was not of CpxA-His6 into CpxA-His6 protein was incorporated into E. coli the as 1995; PubMed Scopus Google Scholar). The of CpxA-His6 into was not analyze the of CpxA-His6 in proteoliposomes the susceptibility of its domain to was In intact the is on the cytoplasmic of the Because of the CpxA-His6 in the proteoliposomes a as a of shown by an and the of the of the CpxA-His6 protein in proteoliposomes is in the As a for the of the was incorporated with of was the protein was by E. S. J. Biol. PubMed Google Scholar). of CpxA-His6 in CpxA-His6 proteoliposomes were in the of The increased for Autokinase activity of CpxA-His6 proteoliposomes was with that of CpxA-His6 in not we of the CpxA-His6 proteoliposomes to In CpxA-His6 in proteoliposomes was for and was The was and were the of the to was we the phosphatase activity of CpxA-His6 in we the of Purified protein was by proteoliposomes as was the and in the and of were was for a of of the of the of CpxA, proteoliposomes were and was a of The of was In the of the was to In the of increased the first This effect was as it in the of the it was not to the phosphatase activity of CpxA. A effect was reported for and its response regulator A. J. Biol. 2001; PubMed Scopus Google Scholar). and activities. of and pH on the of CpxA-His6 in vivo suggested that the Cpx system might be involved in osmolarity (12Jubelin G. Vianney A. Beloin C. Ghigo J.M. Lazzaroni J.C. Lejeune P. Dorel C. J. Bacteriol. 2005; 187: 2038-2049Crossref PubMed Scopus (209) Google Scholar). we the autokinase activity of CpxA-His6 in proteoliposomes in the of It was that activity of CpxA-His6 was stimulated in the of and also had a effect but to a extent. In other osmotic active solutes as sucrose, and not CpxA autokinase the glycine betaine, and that are in to an osmotic had no effect. We also analyzed the effect of on CpxA-His6 activity a between and KCl. The effect of was to be a of the a not In vivo showed that the Cpx system is activated by pH P.N. Silhavy T.J. J. Bacteriol. 1998; 180: 831-839Crossref PubMed Google Scholar). we analyzed the effect of pH on the activity of CpxA-His6 We a of CpxA autokinase activity by pH but not by or pH of the Autokinase and of CpxA-His6 in by of further characterized the molecular properties of CpxA in more by the effect of that are to inhibit The used in study are the Closantel J. Z. H. 1998; PubMed Scopus Google and PubMed Scopus Google Scholar), the small Yamaguchi Y. J. Biol. 2000; PubMed Scopus Google Scholar), the PubMed Scopus Google Scholar), and the Because were in was used as an Interestingly, a of the activity of reconstituted CpxA-His6 by in to the CpxA-His6 in proteoliposomes we that the inhibitory effect of Closantel not the inhibitory effect of the Closantel was effect. In the Closantel the activity of CpxA-His6 The was to be we reduced activity of CpxA-His6 with a of inhibited the activity of CpxA-His6 The of CpxA protein was of the In to the sensor kinase we vanadate, a of and reconstituted is to inhibit the of a in the of Biol. 1995; Google and to the of in the of Sci. 1980; Scopus Google Scholar, S. S. E. 1995; PubMed Scopus Google Scholar). a of the activity of CpxA-His6 to of the We also analyzed the effect of on the phosphotransfer activity of CpxA-His6 in were for of the in to the effect on the CpxA phosphotransfer activity was increased by to of the not Closantel the of the CpxA-His6 but of CpxA-His6 in and were to be for and phosphotransfer activities of reconstituted and to our Closantel not inhibit activities CpxA-His6 was reconstituted in study we the effect of Closantel on the activity of with that of reconstituted In to the effect on the reconstituted CpxA the activity of solubilized protein was reduced to of the by Closantel that the Closantel was not able to inhibit reconstituted CpxA-His6 of its in the we a of Closantel, no activity was for the solubilized but the activity of the protein in proteoliposomes was not inhibited of These on the Autokinase of with CpxA-His6 clear between the and the protein reconstituted in the in susceptibility of the is a of CpxA or it is a of sensor we analyzed the effect of Closantel and of on the sensor kinase of E. and of was out as A. J. Biol. 2001; PubMed Scopus Google Scholar). As for the CpxA protein we by the The of protein was reduced for the solubilized protein to 50% and for the reconstituted protein to In of our finding for CpxA the solubilized was inhibited by Closantel but not the reconstituted protein. In was not able to inhibit the activity of the the results of our that the and reconstituted of membrane sensor in biochemical This the of the reconstituted and not the of a sensor of CpxA-His6 by vivo showed that overproduction of the periplasmic CpxP protein leads to of the Cpx signaling (17Raivio T.L. Laird M.W. Joly J.C. Silhavy T.J. Mol. Microbiol. 2000; 37: 1186-1197Crossref PubMed Scopus (83) Google Scholar). in vitro system an to is of direct interaction between the CpxP protein and the CpxA sensor kinase of the involvement of other factors can be In addition, our in vitro system to analyze which function of the CpxA protein is by CpxP. CpxP might inhibit the activity or the phosphatase activity of CpxA (17Raivio T.L. Laird M.W. Joly J.C. Silhavy T.J. Mol. Microbiol. 2000; 37: 1186-1197Crossref PubMed Scopus (83) Google Scholar). analyze the inhibitory effect of CpxP on we CpxP protein with solubilized CpxP was in a no of activity of the solubilized CpxA-His6 protein by CpxP was not analyze the effect of CpxP on reconstituted CpxP was incorporated into proteoliposomes to of protein to the periplasmic of CpxA. we the between CpxP and CpxA-His6 during the to the in the proteoliposomes was CpxP inhibited the activity of CpxA-His6 by Interestingly, the was to inhibit CpxA activity of the in by we the effect of CpxP on the CpxR phosphorylation Because our for CpxA kinase activity be by the inhibitory effect of CpxP on CpxA and in a of the of a signaling pathway is not we an in vitro signal transduction for the Purified CpxA-His6 in proteoliposomes and were a of and the was by the of were and was to CpxA activities to and were an and As shown CpxA a autokinase and phosphotransfer activities to and a activity CpxR This in vitro signaling system was used to analyze the effect of CpxP on the CpxA-His6 and CpxP were with a and the was out as As shown CpxP a in CpxA Interestingly, CpxP not the phosphorylation of CpxR indicating that CpxP not the phosphatase activity of CpxA as by (17Raivio T.L. Laird M.W. Joly J.C. Silhavy T.J. Mol. Microbiol. 2000; 37: 1186-1197Crossref PubMed Scopus (83) Google Scholar). As we not an inhibitory effect of CpxP on the CpxR phosphorylation status we might be to an of CpxR protein in the we reduced the between the proteins to This not the phosphorylation status of the CpxA protein was reduced in proteoliposomes but also that of CpxR protein our that CpxP CpxA autokinase but not phosphatase In addition, the between the sensor kinase CpxA and the response regulator CpxR to be critical for an inhibitory effect mediated by the periplasmic CpxP protein on the complete signaling The of the study was to an in vitro system to the biochemical properties of the envelope stress system and its interaction with the periplasmic CpxP protein. we a to and the membrane-integral CpxA protein of E. coli into proteoliposomes as a fusion protein. The of a fusion is for the and of membrane-anchored histidine such as the E. coli J. Biol. 1997; PubMed Scopus Google and A. J. Biol. 2001; PubMed Scopus Google activities were for phosphorylation with the cytoplasmic histidine kinase domain of the CpxA protein T. H. A. J. Biol. 2005; PubMed Scopus Google Scholar). In of the CpxA of the to CpxR protein was and was not complete In a phosphotransfer to CpxR was shown for the cytoplasmic histidine kinase domain of CpxA T. H. A. J. Biol. 2005; PubMed Scopus Google Scholar). our are in with a for the reconstituted protein that between the domains of sensor activities J. Biol. 1997; PubMed Scopus Google Scholar). on the effect of solutes and pH in vivo of Cpx pathway activation by pH P.N. Silhavy T.J. J. Bacteriol. 1998; 180: 831-839Crossref PubMed Google Scholar). In addition, our the of for CpxA and activities. Other solutes such as and NaCl also mediated activation of CpxA activities to a with KCl. Because and not effect on CpxA activities the also that is not by an of as suggested by recent in vivo (12Jubelin G. Vianney A. Beloin C. Ghigo J.M. Lazzaroni J.C. Lejeune P. Dorel C. J. Bacteriol. 2005; 187: 2038-2049Crossref PubMed Scopus (209) Google Scholar). the proline or glycine betaine, which are might to be in not a effect on CpxA autokinase the solubilized and reconstituted CpxA-His6 were further characterized for susceptibility to sensor kinase inhibitors. the of our is the first that of on a membrane-anchored sensor kinase that was as a protein and reconstituted into histidine the as of are the kinase that is for S. J. J. A. S. J.M. Proc. Natl. Acad. Sci. U. S. A. 1998; PubMed Scopus Google Scholar), the E. coli kinase involved in Yamaguchi Y. J. Biol. 2000; PubMed Scopus Google and the kinase for production of of S. Proc. Natl. Acad. Sci. U. S. A. 1993; PubMed Scopus Google Scholar). the effect of sensor kinase on some membrane-integral histidine was also proteins were analyzed and as in the of kinase PubMed Scopus Google Scholar), or membrane as in the of the kinase of J. Bacteriol. 1999; 181: PubMed Google were We and as for autokinase and phosphotransfer activities of both the and the reconstituted CpxA-His6 protein. and not inhibit activities of the CpxA protein. Interestingly, Closantel inhibited the activities of solubilized CpxA-His6 protein but not of CpxA-His6 in This observation was by the of the reconstituted protein of E. CpxA, is an membrane protein with a cytosolic a acid periplasmic domain by domains and a cytoplasmic domain S. S. J. Biol. PubMed Google Scholar). As for CpxA, the was inhibited by our results that membrane-integral histidine activities into for the histidine kinase Closantel the of the membrane protein. The of the of the signal transduction in vitro to analyze in more the in vivo observation that the periplasmic protein CpxP the Cpx signaling (1Raivio T.L. Silhavy T.J. Annu. Rev. Microbiol. 2001; 55: 591-624Crossref PubMed Scopus (313) Google Scholar). In we the a direct interaction between CpxP and CpxA is A of was to inhibit the activity of the sensor kinase CpxA to In a CpxP that was to an N-terminal reduced the activity of CpxA by This finding recent in vivo that the N-terminal of the CpxP protein is critical for its inhibitory activity on the Cpx signaling T.L. J. Bacteriol. 2005; 187: PubMed Scopus Google Scholar). Interestingly, an inhibitory effect on the phosphorylation status of the response regulator CpxR was not indicating that the phosphotransfer the phosphatase activities of CpxA are by CpxP. we that the phosphotransfer is In other CpxA the to we that the between the sensor protein CpxA and its regulator CpxR is critical for the signaling CpxP decreased the of CpxR the of was to In we that CpxA the of the to CpxR and the of In addition, by an in vitro signal transduction for the system we were able to that the periplasmic CpxP protein the autokinase activity of CpxA and not its phosphatase activity as (16De Wulf P. Kwon O. Lin E.C. J. Bacteriol. 1999; 181: 6772-6778Crossref PubMed Google Scholar). As the in vitro system excludes the involvement of other factors, is the first biochemical for direct protein-protein interaction between we that CpxP the of signal the pathway in a We for and for further and Betton for and We for We for Closantel and We are to for critical of the with
Kooperationen0
Bestätigte Forscher↔Partner-Paare aus HU-FIS — Gold-Standard-Positive für das Matching.
Aus HU-FIS sind keine Kooperationen für diese Person gemeldet.