PAAR-Rhs proteins harbor various C-terminal toxins to diversify the antibacterial pathways of type VI secretion systems.

摘要: The type VI secretion system (T6SS) of bacteria plays a key role in competing for specific niches by the contact-dependent killing competitors. Recently, Rhs proteins with polymorphic C-terminal toxin-domains that inhibit or kill neighboring cells were identified. In this report, we identified novel an MPTase4 (Metallopeptidase-4) domain (designated as Rhs-CT1) showed antibacterial effect via T6SS Escherichia coli. We managed to develop strategy matching diagnostic domain-architecture Rhs-CT1 (Rhs N-terminal PAAR-motif and toxin domain) effector retrieval discovered series Rhs-CTs E. Indeed, screened Rhs-CT3 REase-3 (Restriction endonuclease-3) also mediated interbacterial antagonism. Further analysis revealed vgrGO1 eagR/DUF1795 (upstream rhs-ct) required delivery Rhs-CTs, suggesting eagR potential chaperone. addition chaperoned neighborless could be classified into distinct family (Rhs-Nb) sharing close evolutionary relationship T6SS2-Rhs (encoded T6SS2 cluster coli). Notably, Rhs-Nb-CT5 was confirmed bioinformatically experimentally mediate antagonism Hcp2B-VgrG2 module. further analysis, various toxin/immunity pairs extensive bacterial species systematically eight referential clans, greatly diversify pathways T6SS.