Mechanism for sortase localization and the role of sortase localization in efficient pilus assembly in Enterococcus faecalis

Kimberly A. Kline, Andrew L. Kau, Swaine L. Chen, Adeline Lim, Jerome S. Pinkner, Jason Rosch, Sreedhar R. Nallapareddy, Barbara E. Murray, Birgitta Henriques-Normark, Wandy Beatty, Michael G. Caparon, Scott J. Hultgren

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

Pathogenic streptococci and enterococci primarily rely on the conserved secretory (Sec) pathway for the translocation and secretion of virulence factors out of the cell. Since many secreted virulence factors in gram-positive organisms are subsequently attached to the bacterial cell surface via sortase enzymes, we sought to investigate the spatial relationship between secretion and cell wall attachment in Enterococcus faecalis. We discovered that sortase A (SrtA) and sortase C (SrtC) are colocalized with SecA at single foci in the enterococcus. The SrtA-processed substrate aggregation substance accumulated in single foci when SrtA was deleted, implying a single site of secretion for these proteins. Furthermore, in the absence of the pilus-polymerizing SrtC, pilin subunits also accumulate in single foci. Proteins that localized to single foci in E. faecalis were found to share a positively charged domain flanking a transmembrane helix. Mutation or deletion of this domain in SrtC abolished both its retention at single foci and its function in efficient pilus assembly. We conclude that this positively charged domain can act as a localization retention signal for the focal compartmentalization of membrane proteins.

Original languageEnglish
Pages (from-to)3237-3247
Number of pages11
JournalJournal of bacteriology
Volume191
Issue number10
DOIs
StatePublished - May 2009

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