The role of this operon in Yersinia is unknown, although secondary structure prediction using the online software tool Phyre (Kelley & Sternberg, 2009) suggests that YPK_1206 is an IHF-like DNA bending protein (Fig.

S4). Although the amino acid sequences of these two proteins possess low similarity, their secondary structures share high similarity Talazoparib datasheet (Swinger & Rice, 2004). These analyses suggest that YPK_1206 may have roles in DNA bending and SraG may function as a regulatory element in this process. Comparative genomic analysis revealed that the YPK_1206 and YPK_1205 genes are only present in Y. pseudotuberculosis YpIII, Yersinia enterocolitica palearctica and Y. enterocolitica W22703, and YPK_1206 and YPK_1205 in YpIII share 90% similarity with Y. enterocolitica. The interaction region between YPK_1206 and SraG is conserved in both Y. enterocolitica Ibrutinib supplier strains, which suggests that SraG may be involved in YPK_1206-1205 operon regulation. Our results also suggest a role of SraG in YPK_1206-1205 mRNA

stability (Fig. 3 and Fig. S2), although further experiments are needed to prove this hypothesis. Our results also revealed that the coding sequence of YPK_1206 is necessary for SraG-mediated regulation, which suggests that SraG may negatively regulate the YPK_1206 mRNA via interaction with this region. This is similar to MicC-induced ompD mRNA regulation, which requires the C terminus of RNase E to be involved (Pfeiffer et al., 2009). RNase E has an established function in stable RNA, antisense RNA decay and sRNA-mediated regulation (Afonyushkin et al., 2005; Pfeiffer et al., 2009). Decreasing YPK_1206 Oxymatrine mRNA level by SraG may also rely upon RNase E, which needs to be further investigated. It has been shown that PNPase expression is post-transcriptionally regulated by affecting mRNA stability (Briani et al., 2008). The primary transcript of pnp is very efficiently processed by RNase III, which creates a structure

that is susceptible to specific recognition by PNPase, inducing its autocontrol (Briani et al., 2008). RNA structure prediction by MFOLD (Zuker, 2003) revealed a hairpin structure in the pnp mRNA leader sequence, which could be recognized by RNase III (data not shown). The hairpin region of pnp overlaps with the sraG gene, so deletion of the sraG gene may abrogate the hairpin structure and disrupt the autoregulation of pnp mRNA to increase the expression of PNPase. The effect of SraG on pnp mRNA is under investigation. Our proteomic analysis revealed that the mutant of sraG regulated expression of 16 proteins. Bioinformatic analysis demonstrated that there is no sequence similarity between those potential targets. However, three proteins are related to maltose metabolism and belong to two adjacent divergently transcribed operons. This suggests that SraG may be also involved in regulation of maltose metabolism.