Yersinia enterocolitica Phage Shock Proteins B and C Can Form Homodimers and Heterodimers In Vivo with the Possibility of Close Association between Multiple Domains

• Published in: Journal of Bacteriology 2011-10, Vol.193 (20), p.5747-5758
• Main Authors: Gueguen, Erwan, Flores-Kim, Josué, Darwin, Andrew J
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; bacteriophages; Biological and medical sciences; cell membranes; crosslinking; cysteine; Dimerization; Ecology, environment; formaldehyde; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Bacterial; Genetics and Molecular Biology; Heat shock proteins; hydrophobicity; leucine; Life Sciences; membrane proteins; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microbiology; Microbiology and Parasitology; Miscellaneous; Molecular Sequence Data; Protein Binding; Protein Structure, Tertiary; secretin; stress response; Survival analysis; Symbiosis; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Virology; virulence; Yersinia enterocolitica; Yersinia enterocolitica - chemistry; Yersinia enterocolitica - genetics; Yersinia enterocolitica - metabolism
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/JB.05080-11

The Yersinia enterocolitica phage shock protein (Psp) stress response is essential for virulence and for survival during the mislocalization of outer membrane secretin proteins. The cytoplasmic membrane proteins PspB and PspC are critical components involved in regulating psp gene expression and in facilitating tolerance to secretin-induced stress. Interactions between PspB and PspC monomers might be important for their functions and for PspC stability. However, little is known about these interactions and there are conflicting reports about the ability of PspC to dimerize. To address this, we have used a combination of independent approaches to systematically analyze the ability of PspB and PspC to form dimers in vivo. Formaldehyde cross-linking of the endogenous chromosomally encoded proteins in Y. enterocolitica revealed discrete complexes corresponding in size to PspB-PspB, PspC-PspC, and PspB-PspC. Bacterial two-hybrid analysis corroborated these protein associations, but an important limitation of the two-hybrid approach was uncovered for PspB. A series of PspB and PspC proteins with unique cysteine substitutions at various positions was constructed. In vivo disulfide cross-linking experiments with these proteins further supported close association between PspB and PspC monomers. Detailed cysteine substitution analysis of predicted leucine zipper-like amphipathic helices in both PspB and PspC suggested that their hydrophobic faces could form homodimerization interfaces.