Cell-to-cell interaction requires optimal positioning of a pilus tip adhesin modulated by gram-positive transpeptidase enzymes

• DOI: 10.1073/pnas.1907733116
• Publication Date: 2019-08-20T00:24:53Z
• Authors: Chungyu Chang; Chenggang Wu; Jerzy Osipiuk; Sara D. Siegel; Shiwei Zhu; Xiangan Liu; Andrzej Joachimiak; Robert T. Clubb; Asis Das; Hung Ton-That
• Keywords: Sortase; Pilin; Fimbriae Proteins; Sortase A

Assembly of pili on the gram-positive bacterial cell wall involves 2 conserved transpeptidase enzymes named sortases: One for polymerization pilin subunits and another anchoring to peptidoglycan. How this machine controls pilus length whether is critical cell-to-cell interactions remain unknown. We report here in Actinomyces oris , a key colonizer development oral biofilms, that genetic disruption its housekeeping sortase SrtA generates exceedingly long pili, catalyzed by pilus-specific SrtC2 possesses both functions. Remarkably, srtA- deficient mutant fails mediate interspecies interactions, or coaggregation, even though coaggregation factor CafA present at tip. Increasing ectopic expression srtA progressively shortens restores accordingly, while elevated levels shaft pilins produce block + bacteria. With structural studies, we uncovered elements partake recognition substrates regulate inducing capture transfer polymers wall. Evidently, requires proper positioning tip adhesin via modulation SrtA.