Try a new search

Format these results:

Searched for:



Total Results:


(Re)Engaging Faculty During and After a Health Pandemic: Programmatic Strategies for Learning and Wellness

Savitzky, Diana C; Rekawek, Patricia; Shelov, Steven; Nonaillada, Jeannine
ISSN: 2153-1900
CID: 5309542

Analysis of the Yersinia enterocolitica PspBC proteins defines functional domains, essential amino acids and new roles within the phage-shock-protein response

Gueguen, Erwan; Savitzky, Diana C; Darwin, Andrew J
The Yersinia enterocolitica phage-shock-protein (Psp) stress response system is activated by mislocalized outer-membrane secretin components of protein export systems and is essential for virulence. The cytoplasmic membrane proteins PspB and PspC were proposed to be dual function components of the system, acting both as positive regulators of psp gene expression and to support survival during secretin-induced stress. In this study we have uncoupled the regulatory and physiological functions of PspBC and discovered unexpected new roles, functional domains and essential amino acids. First, we showed that PspB controls PspC concentration by both pre- and post-transcriptional mechanisms. We then screened for PspBC mutants with altered transcriptional regulatory function. Unexpectedly, we identified PspB and PspC mutants that activated psp gene expression in the absence of secretin-induced stress. Together with a subsequent truncation analysis, this revealed that the PspC cytoplasmic domain plays an unforeseen role in negatively regulating psp gene expression. Conversely, mutations within the PspC periplasmic domain abolished its ability to activate psp gene expression. Significantly, PspC mutants unable to activate psp gene expression retained their ability to support survival during secretin-induced stress. These data provide compelling support for the proposal that these two functions are independent
PMID: 19775245
ISSN: 1365-2958
CID: 105336

Global analysis of tolerance to secretin-induced stress in Yersinia enterocolitica suggests that the phage-shock-protein system may be a remarkably self-contained stress response

Seo, Jin; Savitzky, Diana C; Ford, Emily; Darwin, Andrew J
The phage-shock-protein (Psp) system is essential for Yersinia enterocolitica virulence. Mislocalized secretins induce psp gene expression, and kill psp null strains. We used transposon mutagenesis to investigate whether other genes are required to tolerate secretin-induced stress. Our motivation included the possibility of identifying signal transducers required to activate psp gene expression. Besides Psp, only defects in the RpoE system and the TrkA potassium transporter caused secretin sensitivity. These mutations did not cause the same specific/severe sensitivity as defects in the Psp system, nor did they affect psp gene expression. The Escherichia coli Psp system was reported to be induced via the ArcB redox sensor and to activate anaerobic metabolism. Our screen did not identify arcB, or any genes involved in anaerobic metabolism/regulation. Therefore, we investigated the role of ArcB in Y. enterocolitica and E. coli. ArcB was not required for secretin-dependent induction of psp gene expression. Furthermore, microarray analysis uncovered a restricted transcriptional response to prolonged secretin stress in Y. enterocolitica. Taken together, these data do not support the proposal that the Psp system is induced via ArcB and activates anaerobic metabolism. Rather, they suggest that Psp proteins may sense an inducing trigger and mediate their physiological output(s) directly
PMID: 17608794
ISSN: 0950-382x
CID: 73872