The Experts below are selected from a list of 6315 Experts worldwide ranked by ideXlab platform
Chin Ha Chung - One of the best experts on this subject based on the ideXlab platform.
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the hslu atpase acts as a molecular chaperone in prevention of aggregation of Sula an inhibitor of cell division in escherichia coli
FEBS Letters, 2000Co-Authors: I S Seong, Jung Wook Lee, Keiji Tanaka, Chin Ha ChungAbstract:HslVU is an ATP-dependent protease consisting of two multimeric components: the HslU ATPase and the HslV peptidase. Sula, which is an inhibitor of cell division and has high tendency of aggregation, is degraded by HslVU protease. Here we show that HslU plays a role not only as a regulatory component for the HslV-mediated proteolysis but also as a molecular chaperone. Purified HslU prevented aggregation of Sula in a concentration-dependent fashion. This chaperone activity required oligomerization of HslU subunits, which could be achieved by ATP-binding or in the presence of high HslU protein concentrations. hsl mutation reduced the Sula-mediated inhibition of cell growth and this effect could be reversed upon overproduction of HslU, suggesting that HslU promotes the ability of Sula to block cell growth through its chaperone function. Thus, HslU appears to have two antagonistic functions: one as a chaperone for promotion of the ability of Sula in cell growth inhibition by preventing Sula aggregation and the other as the regulatory component for elimination of Sula by supporting the HslV-mediated degradation.
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atp dependent degradation of Sula a cell division inhibitor by the hslvu protease in escherichia coli
FEBS Letters, 1999Co-Authors: I S Seong, Soon Ji Yoo, Jae Hong Seol, Chin Ha ChungAbstract:HslVU is an ATP-dependent protease consisting of two multimeric components, the HslU ATPase and the HslV peptidase. To gain an insight into the role of HslVU in regulation of cell division, the reconstituted enzyme was incubated with Sula, an inhibitor of cell division in Escherichia coli, or its fusion protein with maltose binding protein (MBP). HslVU degraded both proteins upon incubation with ATP but not with its non-hydrolyzable analog, ATPγS, indicating that the degradation of Sula requires ATP hydrolysis. The pulse-chase experiment using an antibody raised against MBP-Sula revealed that the stability of Sula increased in hsl mutants and further increased in lon/hsl double mutants, indicating that Sula is an in vivo substrate of HslVU as well as of protease La (Lon). These results suggest that HslVU in addition to Lon plays an important role in regulation of cell division through degradation of Sula.
L I Rothfield - One of the best experts on this subject based on the ideXlab platform.
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cell division inhibitors Sula and minc mind block septum formation at different steps in the assembly of the escherichia coli division machinery
Molecular Microbiology, 2000Co-Authors: Sheryl S Justice, Jorge Garcialara, L I RothfieldAbstract:Sula and MinCD are specific inhibitors of cell division in Escherichia coli. In this paper, size exclusion chromatography was used to study the effect of the Sula and MinCD division inhibitors on the oligomerization state of endogenous FtsZ in cytoplasmic extracts, and immunofluorescence microscopy was used to determine the effect of Sula and MinCD on the formation of FtsZ, FtsA and ZipA rings at potential division sites. Sula prevented the formation of high-molecular-weight FtsZ polymers by interfering with FtsZ dimerization and subsequent oligomerization. In contrast, the MinCD division inhibitor did not prevent the oligomerization of FtsZ in the cell extracts or the formation of FtsZ and ZipA ring structures in vivo. However, MinCD did prevent the formation of FtsA rings. Increased expression of ftsA suppressed MinCD-induced division inhibition, but had no effect on Sula-induced division inhibition. These results indicate that MinCD blocks the assembly of the septation machinery at a later step than Sula, at the stage at which FtsA is added to the FtsZ ring.
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cell division inhibitors Sula and minc mind block septum formation at different steps in the assembly of the escherichia coli division machinery
Molecular Microbiology, 2000Co-Authors: Sheryl S Justice, Jorge Garcialara, L I RothfieldAbstract:Sula and MinCD are specific inhibitors of cell division in Escherichia coli. In this paper, size exclusion chromatography was used to study the effect of the Sula and MinCD division inhibitors on the oligomerization state of endogenous FtsZ in cytoplasmic extracts, and immunofluorescence microscopy was used to determine the effect of Sula and MinCD on the formation of FtsZ, FtsA and ZipA rings at potential division sites. Sula prevented the formation of high-molecular-weight FtsZ polymers by interfering with FtsZ dimerization and subsequent oligomerization. In contrast, the MinCD division inhibitor did not prevent the oligomerization of FtsZ in the cell extracts or the formation of FtsZ and ZipA ring structures in vivo. However, MinCD did prevent the formation of FtsA rings. Increased expression of ftsA suppressed MinCD-induced division inhibition, but had no effect on Sula-induced division inhibition. These results indicate that MinCD blocks the assembly of the septation machinery at a later step than Sula, at the stage at which FtsA is added to the FtsZ ring.
Sheryl S Justice - One of the best experts on this subject based on the ideXlab platform.
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filamentation by escherichia coli subverts innate defenses during urinary tract infection
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Sheryl S Justice, David A Hunstad, Patrick C Seed, Scott J HultgrenAbstract:To establish disease, an infecting organism must overcome a vast array of host defenses. During cystitis, uropathogenic Escherichia coli (UPEC) subvert innate defenses by invading superficial umbrella cells and rapidly increasing in numbers to form intracellular bacterial communities (IBCs). In the late stages of the IBC pathway, filamentous and bacillary UPEC detach from the biofilm-like IBC, fluxing out of this safe haven to colonize the surrounding epithelium and initiate subsequent generations of IBCs, and eventually they establish a quiescent intracellular reservoir. Filamentous UPEC are not observed during acute infection in mice lacking functional Toll-like receptor 4 (TLR4), suggesting that the filamentous phenotype arises in response to host innate immunity. We investigated Sula, a cell division inhibitor associated with the SOS response, to gain insight into the role of filamentous UPEC in pathogenesis. A transcriptional reporter from PSula revealed spatial and temporal differences in expression within IBCs, and it was active in the majority of filamentous UPEC. Although UTI89 and UTI89 ΔSula both formed first-generation IBCs equally well, UTI89 ΔSula was sharply attenuated in formation of second-generation IBCs and establishment of the quiescent intracellular reservoir. The virulence of UTI89 ΔSula was restored in TLR4-deficient mice, suggesting that filamentation facilitates the transition to additional rounds of IBC formation by subverting innate immune responses. These findings demonstrate that transient Sula-mediated inhibition of cell division is essential for UPEC virulence in the murine model of cystitis.
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cell division inhibitors Sula and minc mind block septum formation at different steps in the assembly of the escherichia coli division machinery
Molecular Microbiology, 2000Co-Authors: Sheryl S Justice, Jorge Garcialara, L I RothfieldAbstract:Sula and MinCD are specific inhibitors of cell division in Escherichia coli. In this paper, size exclusion chromatography was used to study the effect of the Sula and MinCD division inhibitors on the oligomerization state of endogenous FtsZ in cytoplasmic extracts, and immunofluorescence microscopy was used to determine the effect of Sula and MinCD on the formation of FtsZ, FtsA and ZipA rings at potential division sites. Sula prevented the formation of high-molecular-weight FtsZ polymers by interfering with FtsZ dimerization and subsequent oligomerization. In contrast, the MinCD division inhibitor did not prevent the oligomerization of FtsZ in the cell extracts or the formation of FtsZ and ZipA ring structures in vivo. However, MinCD did prevent the formation of FtsA rings. Increased expression of ftsA suppressed MinCD-induced division inhibition, but had no effect on Sula-induced division inhibition. These results indicate that MinCD blocks the assembly of the septation machinery at a later step than Sula, at the stage at which FtsA is added to the FtsZ ring.
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cell division inhibitors Sula and minc mind block septum formation at different steps in the assembly of the escherichia coli division machinery
Molecular Microbiology, 2000Co-Authors: Sheryl S Justice, Jorge Garcialara, L I RothfieldAbstract:Sula and MinCD are specific inhibitors of cell division in Escherichia coli. In this paper, size exclusion chromatography was used to study the effect of the Sula and MinCD division inhibitors on the oligomerization state of endogenous FtsZ in cytoplasmic extracts, and immunofluorescence microscopy was used to determine the effect of Sula and MinCD on the formation of FtsZ, FtsA and ZipA rings at potential division sites. Sula prevented the formation of high-molecular-weight FtsZ polymers by interfering with FtsZ dimerization and subsequent oligomerization. In contrast, the MinCD division inhibitor did not prevent the oligomerization of FtsZ in the cell extracts or the formation of FtsZ and ZipA ring structures in vivo. However, MinCD did prevent the formation of FtsA rings. Increased expression of ftsA suppressed MinCD-induced division inhibition, but had no effect on Sula-induced division inhibition. These results indicate that MinCD blocks the assembly of the septation machinery at a later step than Sula, at the stage at which FtsA is added to the FtsZ ring.
I S Seong - One of the best experts on this subject based on the ideXlab platform.
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the hslu atpase acts as a molecular chaperone in prevention of aggregation of Sula an inhibitor of cell division in escherichia coli
FEBS Letters, 2000Co-Authors: I S Seong, Jung Wook Lee, Keiji Tanaka, Chin Ha ChungAbstract:HslVU is an ATP-dependent protease consisting of two multimeric components: the HslU ATPase and the HslV peptidase. Sula, which is an inhibitor of cell division and has high tendency of aggregation, is degraded by HslVU protease. Here we show that HslU plays a role not only as a regulatory component for the HslV-mediated proteolysis but also as a molecular chaperone. Purified HslU prevented aggregation of Sula in a concentration-dependent fashion. This chaperone activity required oligomerization of HslU subunits, which could be achieved by ATP-binding or in the presence of high HslU protein concentrations. hsl mutation reduced the Sula-mediated inhibition of cell growth and this effect could be reversed upon overproduction of HslU, suggesting that HslU promotes the ability of Sula to block cell growth through its chaperone function. Thus, HslU appears to have two antagonistic functions: one as a chaperone for promotion of the ability of Sula in cell growth inhibition by preventing Sula aggregation and the other as the regulatory component for elimination of Sula by supporting the HslV-mediated degradation.
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atp dependent degradation of Sula a cell division inhibitor by the hslvu protease in escherichia coli
FEBS Letters, 1999Co-Authors: I S Seong, Soon Ji Yoo, Jae Hong Seol, Chin Ha ChungAbstract:HslVU is an ATP-dependent protease consisting of two multimeric components, the HslU ATPase and the HslV peptidase. To gain an insight into the role of HslVU in regulation of cell division, the reconstituted enzyme was incubated with Sula, an inhibitor of cell division in Escherichia coli, or its fusion protein with maltose binding protein (MBP). HslVU degraded both proteins upon incubation with ATP but not with its non-hydrolyzable analog, ATPγS, indicating that the degradation of Sula requires ATP hydrolysis. The pulse-chase experiment using an antibody raised against MBP-Sula revealed that the stability of Sula increased in hsl mutants and further increased in lon/hsl double mutants, indicating that Sula is an in vivo substrate of HslVU as well as of protease La (Lon). These results suggest that HslVU in addition to Lon plays an important role in regulation of cell division through degradation of Sula.
Joe Lutkenhaus - One of the best experts on this subject based on the ideXlab platform.
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investigation of regulation of ftsz assembly by Sula and development of a model for ftsz polymerization
Journal of Bacteriology, 2008Co-Authors: Alex Dajkovic, Amit Mukherjee, Joe LutkenhausAbstract:In Escherichia coli FtsZ organizes into a cytoskeletal ring structure, the Z ring, which effects cell division. FtsZ is a GTPase, but the free energy of GTP hydrolysis does not appear to be used for generation of the constriction force, leaving open the question of the function of the GTPase activity of FtsZ. Here we study the mechanism by which Sula, an inhibitor of FtsZ induced during the SOS response, inhibits FtsZ function. We studied the effects of Sula on the in vitro activities of FtsZ, on Z rings in vivo, and on a kinetic model for FtsZ polymerization in silico. We found that the binding of Sula to FtsZ is necessary but not sufficient for inhibition of polymerization, since the assembly of FtsZ polymers in the absence of the GTPase activity was not inhibited by Sula. We developed a new model for FtsZ polymerization that accounts for the cooperativity of FtsZ and could account for cooperativity observed in other linear polymers. When Sula was included in the kinetic scheme, simulations revealed that Sula with strong affinity for FtsZ delayed, but did not prevent, the assembly of polymers when they were not hydrolyzing GTP. Furthermore, the simulations indicated that Sula controls the assembly of FtsZ by binding to a polymerization-competent form of the FtsZ molecule and preventing it from participating in assembly. In vivo stoichiometry of the disruption of Z rings by Sula suggests that FtsZ may undergo two cooperative transitions in forming the Z ring.
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inhibition of ftsz polymerization by Sula an inhibitor of septation in escherichia coli
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Amit Mukherjee, Chune Cao, Joe LutkenhausAbstract:The bacterial cell division protein FtsZ assembles into the cytokinetic Z ring that directs cytokinesis in prokaryotes. In Escherichia coli the formation of the Z ring is prevented by induction of the cell division inhibitor Sula (SfiA), a component of the SOS response. Here we show that a MalE-Sula fusion that retains this inhibitory function in vivo inhibits the GTPase activity and polymerization of FtsZ in vitro. MalE-Sula10, which does not block Z ring formation in vivo, is unable to inhibit the GTPase activity and polymerization in vitro. Furthermore, FtsZ114, which is refractory to Sula in vivo, is not inhibited by MalE-Sula. These results indicate that Sula blocks Z ring formation by blocking FtsZ polymerization.
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cell division inhibitors Sula and mincd prevent formation of the ftsz ring
Journal of Bacteriology, 1993Co-Authors: Erfei Bi, Joe LutkenhausAbstract:Abstract Immunoelectron microscopy was used to assess the effects of inhibitors of cell division on formation of the FtsZ ring in Escherichia coli. Induction of the cell division inhibitor Sula, a component of the SOS response, or the inhibitor MinCD, a component of the min system, blocked formation of the FtsZ ring and led to filamentation. Reversal of Sula inhibition by blocking protein synthesis in Sula-induced filaments led to a resumption of FtsZ ring formation and division. These results suggested that these inhibitors block cell division by preventing FtsZ localization into the ring structure. In addition, analysis of min mutants demonstrated that FtsZ ring formation was also associated with minicell formation, indicating that all septation events in E. coli involve the FtsZ ring.
