The localization and membrane topology of the Yersinia pestis. YscJ lipoprotein an essential component of the type III secretion apparatus, was investigated: YscJ was demonstrated to be an inner membrane (IM) lipoprotein that is anchored to the periplasmic face of the IM via an N-terminal lipid moiety and via a C-terminal transmembrane (TM) domain. Localization of the N-terminal lipid moiety to the IM occurred regardless of the amino-acid residues found in the +2 or +3 positions. IM localization was dependent upon an intact N-terminal domain (amino acids + 1 to + 61), suggesting that this region plays a role in YscJ localization. In contrast, the YscJ C-terminal domain and TM domain were not required for IM localization N-terminal sequence analysis demonstrated that a significant proportion of membrane-localized YscJ laoks N-acylation, the final modification required for Lol-dependent transport of a lipoprotein to the OM. Interestingly, attachment of the N-terminus to the IM was required for YscJ function; however, the YscJ secretion signal and lipo-box could be functionally replaced by the first TM domain of the YscV protein, suggesting that the mechanism of attachment to the IM was not critical.
ASJC Scopus subject areas