Contributions of F‐specific subunits to the F plasmid‐encoded type IV secretion system and F pilus

• DOI: 10.1111/mmi.14908
• Publication Date: 2022-04-18T04:23:41Z
• Authors: Kouhei Kishida; Rachel E. Bosserman; Laith Harb; Pratick Khara; Liqiang Song; Bo Hu; Lanying Zeng; Peter J. Christie
• Keywords: Bacterial conjugation; Horizontal Gene Transfer

F plasmids circulate widely among the Enterobacteriaceae through encoded type IV secretion systems (T4SSF s). Assembly of T4SSF s and associated pili requires 10 VirB/VirD4-like Tra subunits eight or more F-specific subunits. Recently, we presented evidence using in situ cryoelectron tomography (cryoET) that undergo structural transitions when activated for pilus production, assembled are deposited onto alternative basal platforms at cell surface. Here, deleted conserved genes from MOBF12C plasmid pED208 quantitated effects on transfer, production by fluorescence microscopy, elaboration structures cryoET. Mutant phenotypes supported assignment into three functional Classes: (i) TraF, TraH, TraW required all -associated activities, (ii) TraU, TraN, TrbC nonessential but contribute significantly to distinct functions, (iii) TrbB is essential not transfer. Equivalent mutations a phylogenetically distantly related MOB12A conferred similar generally these Class assignments. We present new structure-driven model which steps assembly activation regulate DNA transfer dynamics deposition platforms.