YscP of Yersinia pestis Is a Secreted Component of the Yop Secretion System

Abstract

The Yersinia pestis low-Ca2+ response stimulon is responsible for the environmentally regulated expression and secretion of antihost proteins (V antigen and Yops). We have previously shown that yscO encodes a secreted core component of the Yop secretion (Ysc) mechanism. In this study, we constructed and characterized in-frame deletions in the adjacent gene,yscP, in the yscN–yscU operon. The ΔP1 mutation, which removed amino acids 246 to 333 of YscP, had no effect on Yop expression or secretion, and the mutant protein, YscP1, was secreted, as was YscP in the parent. In contrast, the ΔP2 strain expressed and secreted less of each Yop than did the parent under the inductive conditions of 37°C and the absence of Ca2+, with an exception being YopE, which was only minimally affected by the mutation. The YscP2 protein, missing amino acids 57 to 324 of YscP, was expressed but not secreted by the ΔP2 mutant. The effect of the ΔP2 mutation was at the level of Yop secretion because YopM and V antigen still showed limited secretion when overproduced in trans. Excess YscP also affected secretion: overexpression of YscP in the parent, in either yscP mutant, or in an lcrGmutant effectively shut off secretion. However, co-overexpression of YscO and YscP had no effect on secretion, and YscP overexpression in anlcrE mutant had little effect on Yop secretion, suggesting that YscP acts, in conjunction with YscO, at the level of secretion control of LcrE at the bacterial surface. These findings place YscP among the growing family of mobile Ysc components that both affect secretion and themselves are secreted by the Ysc.

YscP, a Yersinia protein required for Yop secretion that is surface exposed, and released in low Ca2+

“…For this study, we cloned yscP ent and we engineered a larger deletion, removing residues 97±465 in Y. enterocolitica MRS40. At first sight, our results were different from those of Payne and Straley (1999).…”

“…However, this product of about 20 kDa partially restored Yop secretion at 378C in the absence of Ca 21 ions. This result showed that YscP D572324 is partially functional, which explains the leaky phenotype described by Payne and Straley (1999). In conclusion, our results demonstrate that YscP is absolutely required for Yop secretion but that, surprisingly, a severely truncated protein, missing 267 central residues, still has some activity.…”

“…1994; Pettersson et al, 1996;Straley, 1998, 1999). As proposed by Payne and Straley (1999), overproduced YscP in Y. pestis may obstruct the secretion channel or, alternatively, it could associate with other Ysc proteins and sequester one or more factors into non-functional complexes.…”

YopR impacts type III needle polymerization inYersiniaspecies

“…Two ring structures, one in the bacterial plasma membrane and one in the outer membrane, are joined via a central rod that is formed from YscI, which is also thought to connect with the needle protein at the level of the outer YscC ring (Marlovits et al, 2004;Marlovits et al, 2006). Needle polymerization is controlled by YscP, a secreted machine component (Payne and Straley, 1999;Journet et al, 2003). Without yscP, Yersinia polymerize extended needles and are unable to inject effectors into host cells .…”

Yersinia enterocolitica type III secretion of YopR requires a structure in its mRNA

“…What might be different about blocking substrates and non-blocking substrates, which can be rejected from the type III pathway? YopR and YscP do not share obvious physical features, though they do have a few functional attributes in common: neither YopR nor YscP is injected into eukaryotic cells and neither is thought to possess a chaperone (Lee et al, 1998;Payne and Straley, 1999). Both are phenotypically or genetically linked to the formation of the needle filament: yopR is immediately flanked by genes that encode the building blocks for the needle filament though the contribution of YopR to this process is unclear (Allaoui et al, 1995).…”