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Publication Abstract from PubMed

Type II secretion systems (T2SSs) allow diderm bacteria to secrete hydrolytic enzymes, adhesins, or toxins important for growth and virulence. To promote secretion of folded proteins, T2SSs assemble periplasmic filaments called pseudopili or endopili at an inner membrane subcomplex, the assembly platform (AP). Here, we combined biophysical approaches, nuclear magnetic resonance (NMR) and X-ray crystallography, to study the Klebsiella AP components PulL and PulM. We determined the structure and associations of their periplasmic domains and describe the structure of the heterodimer formed by their ferredoxin-like domains. We show how structural complementarity and plasticity favor their association during the secretion process. Cysteine scanning and crosslinking data provided additional constraints to build a structural model of the PulL-PulM assembly in the cellular context. Our structural and functional insights, together with the relative cellular abundance of its components, support the role of AP as a dynamic hub that orchestrates pilus polymerization.

Structure and dynamic association of an assembly platform subcomplex of the bacterial type II secretion system.,Dazzoni R, Li Y, Lopez-Castilla A, Brier S, Mechaly A, Cordier F, Haouz A, Nilges M, Francetic O, Bardiaux B, Izadi-Pruneyre N Structure. 2022 Dec 16:S0969-2126(22)00489-0. doi: 10.1016/j.str.2022.12.003. PMID:36586404^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.