Author:
Chang Chungyu,Wu Chenggang,Osipiuk Jerzy,Siegel Sara D.,Zhu Shiwei,Liu Xiangan,Joachimiak Andrzej,Clubb Robert T.,Das Asis,Ton-That Hung
Abstract
Assembly of pili on the gram-positive bacterial cell wall involves 2 conserved transpeptidase enzymes named sortases: One for polymerization of pilin subunits and another for anchoring pili to peptidoglycan. How this machine controls pilus length and whether pilus length is critical for cell-to-cell interactions remain unknown. We report here inActinomyces oris, a key colonizer in the development of oral biofilms, that genetic disruption of its housekeeping sortase SrtA generates exceedingly long pili, catalyzed by its pilus-specific sortase SrtC2 that possesses both pilus polymerization and cell wall anchoring functions. Remarkably, thesrtA-deficient mutant fails to mediate interspecies interactions, or coaggregation, even though the coaggregation factor CafA is present at the pilus tip. Increasing ectopic expression ofsrtAin the mutant progressively shortens pilus length and restores coaggregation accordingly, while elevated levels of shaft pilins and SrtC2 produce long pili and block coaggregation by SrtA+bacteria. With structural studies, we uncovered 2 key structural elements in SrtA that partake in recognition of pilin substrates and regulate pilus length by inducing the capture and transfer of pilus polymers to the cell wall. Evidently, coaggregation requires proper positioning of the tip adhesin CafA via modulation of pilus length by the housekeeping sortase SrtA.
Funder
HHS | NIH | National Institute of Dental and Craniofacial Research
HHS | NIH | National Institute of Allergy and Infectious Diseases
Publisher
Proceedings of the National Academy of Sciences
Cited by
20 articles.
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