Demarcating SurA Activities Required for Outer Membrane Targeting of Yersinia pseudotuberculosis Adhesins

Abstract

SurA is a periplasmic protein folding factor involved in chaperoning and trafficking of outer membrane proteins across the Gram-negative bacterial periplasm. In addition, SurA also possesses peptidyl-prolyl cis/trans isomerase activity. We have previously reported that in enteropathogenic Yersinia pseudotuberculosis, SurA is needed for bacterial virulence and envelope integrity. In this study, we investigated the role of SurA in the assembly of important Yersinia adhesins. Using genetic mutation, biochemical characterization, and an in vitro-based bacterial host cell association assay, we confirmed that surface localization of the invasin adhesin is dependent on SurA. As a surA deletion also has some impact on the levels of individual components of the BAM complex in the Yersinia outer membrane, abolished invasin surface assembly could reflect both a direct loss of SurA-dependent periplasmic targeting and a potentially compromised BAM complex assembly platform in the outer membrane. To various degrees, the assembly of two other adhesins, Ail and the pH 6 antigen fibrillum PsaA, also depends on SurA. Consequently, loss of SurA leads to a dramatic reduction in Yersinia attachment to eukaryotic host cells. Genetic complementation of surA deletion mutants indicated a prominent role for SurA chaperone function in outer membrane protein assembly. Significantly, the N terminus of SurA contributed most of this SurA chaperone function. Despite a dominant chaperoning role, it was also evident that SurA isomerization activity did make a modest contribution to this assembly process.

The Activity of Escherichia coli Chaperone SurA Is Regulated by Conformational Changes Involving a Parvulin Domain

“…Considering that the PPIase activity of P2 is not involved in regulating P1 inhibition, the P2 domain of SurA may serve a similar role, exhibiting accessory sequestration activity toward some substrates and enhancing the biogenesis of specific proteins (23). Indeed, the PPIase activity of P2 was recently shown to be important for the complete surface localization of Yersinia pseudotuberculosis invasin (36), and at least one SurA parvulin domain is required for complete novobiocin resistance and epithelial cell invasion in uropathogenic E. coli (37). A general role for P2 in the chaperoning of typical SurA substrates, however, remains elusive.…”

Microbial Peptidyl-Prolyl cis / trans Isomerases (PPIases): Virulence Factors and Potential Alternative Drug Targets

“…Host colonization is mediated by several adhesins on the cell surface. The assembly of one of these, the invasin, is strongly dependent on chaperone and PPIase activities of SurA, since complementation of surA deletion with chaperone or PPIase domains only could not entirely restore this deficiency (141). This study is also interesting because it points to the fact that in the absence of SurA, major OMPs, such as OmpF, or components of the BAM complex, i.e., BamA, -C, and -E, are affected in their targeting to the outer membrane.…”

Expeditious screening of candidate proteins for microbial vaccines

“…This group of enzymes catalyzes the folding of virulence proteins into an active confirmation after their secretion and contact with host cells (Behrens-Kneip, 2010;Hermans et al, 2006;Forster et al, 2011). Bacterial PPIase SurA is a periplasmic protein also involved in chaperoning and trafficking of outer membrane proteins across the periplasm in Gram-negative bacteria (Obi and Francis, 2013). The role of SurA in pathogenic processes has been extensively studied in the Enterobacteriaceae (Behrens-Kneip, 2010) as it plays a crucial role in the development of the bacterial flagella and pilus.…”