Topology and Contribution to the Pore Channel Lining of Plasma Membrane-Embedded Shigella flexneri Type 3 Secretion Translocase IpaB

• DOI: 10.1128/mbio.03021-21
• Publication Date: 2021-11-23T09:30:44Z
• Authors: Poyin Chen; Brian C. Russo; Jeffrey K. Duncan...; Natasha Bitar; Keith T. Egger; Marcia B. Goldberg
• Keywords: Transport protein

Shigella spp. are human bacterial pathogens that cause bacillary dysentery. Virulence depends on a type 3 secretion system (T3SS), highly conserved structure present in multiple important and plant pathogens. Upon host cell contact, the T3SS translocon is delivered to membrane, facilitates docking enables delivery of effector proteins into cytosol. The composed two proteins, IpaB IpaC, which together form this multimeric within plasma membranes. interaction IpaC with intermediate filaments, undergoes conformational change allows for onto and, actin polymerization, subsequent translocation through pore. To generate additional insights translocon, we mapped topology membrane-embedded pores using cysteine substitution mutagenesis coupled site-directed labeling proximity-enabled cross-linking by membrane-permeant sulfhydryl reactants. We demonstrate function dependent posttranslational modification plasmid-encoded acyl carrier protein. show first transmembrane domain lines interior pore channel such portion forms funnel-like shape leading In addition, identify regions its cytosolic protrude closely associated channel. Taken together, these results provide framework how arranged translocons natively during infection. IMPORTANCE Type systems nanomachines employed many bacteria, including Shigella, deliver cells virulence alter cellular ways promote Delivery occurs formed membranes proteins. Here, define contributes formation flexneri. specific (transmembrane 1) much portions lie inside loop back and/or These findings new organization serving as conduit