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Diverse roles of TssA‐like proteins in the assembly of bacterial type VI secretion systems
Author(s) -
Schneider Johannes Paul,
Nazarov Sergey,
Adaixo Ricardo,
Liuzzo Martina,
Ringel Peter David,
Stahlberg Henning,
Basler Marek
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2018100825
Subject(s) - biology , secretion , bacterial protein , escherichia coli proteins , microbiology and biotechnology , bacteria , computational biology , genetics , biochemistry
Protein translocation by the bacterial type VI secretion system (T6 SS ) is driven by a rapid contraction of a sheath assembled around a tube with associated effectors. Here, we show that TssA‐like or TagA‐like proteins with a conserved N‐terminal domain and varying C‐terminal domains can be grouped into at least three distinct classes based on their role in sheath assembly. The proteins of the first class increase speed and frequency of sheath assembly and form a stable dodecamer at the distal end of a polymerizing sheath. The proteins of the second class localize to the cell membrane and block sheath polymerization upon extension across the cell. This prevents excessive sheath polymerization and bending, which may result in sheath destabilization and detachment from its membrane anchor and thus result in failed secretion. The third class of these proteins localizes to the baseplate and is required for initiation of sheath assembly. Our work shows that while various proteins share a conserved N‐terminal domain, their roles in T6 SS biogenesis are fundamentally different.