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H aloferax volcanii archaeosortase is required for motility, mating, and C ‐terminal processing of the S ‐layer glycoprotein
Author(s) -
Abdul Halim Mohd Farid,
Pfeiffer Friedhelm,
Zou James,
Frisch Andrew,
Haft Daniel,
Wu Si,
Tolić Nikola,
Brewer Heather,
Payne Samuel H.,
PašaTolić Ljiljana,
Pohlschroder Mechthild
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12248
Subject(s) - s layer , glycoprotein , biology , biochemistry , proteolysis , in silico , transmembrane protein , glycosylation , microbiology and biotechnology , gene , enzyme , receptor
Summary Cell surfaces are decorated by a variety of proteins that facilitate interactions with their environments and support cell stability. These secreted proteins are anchored to the cell by mechanisms that are diverse, and, in archaea, poorly understood. Recently published in silico data suggest that in some species a subset of secreted euryarchaeal proteins, which includes the S ‐layer glycoprotein, is processed and covalently linked to the cell membrane by enzymes referred to as archaeosortases. In silico work led to the proposal that an independent, sortase‐like system for proteolysis‐coupled, carboxy‐terminal lipid modification exists in bacteria (exosortase) and archaea (archaeosortase). Here, we provide the first in vivo characterization of an archaeosortase in the haloarchaeal model organism H aloferax volcanii . Deletion of the artA gene ( HVO _0915) resulted in multiple biological phenotypes: (a) poor growth, especially under low‐salt conditions, (b) alterations in cell shape and the S ‐layer, (c) impaired motility, suppressors of which still exhibit poor growth, and (d) impaired conjugation. We studied one of the ArtA substrates, the S ‐layer glycoprotein, using detailed proteomic analysis. While the carboxy‐terminal region of S ‐layer glycoproteins, consisting of a putative threonine‐rich O ‐glycosylated region followed by a hydrophobic transmembrane helix, has been notoriously resistant to any proteomic peptide identification, we were able to identify two overlapping peptides from the transmembrane domain present in the Δ artA strain but not in the wild‐type strain. This clearly shows that ArtA is involved in carboxy‐terminal post‐translational processing of the S ‐layer glycoprotein. As it is known from previous studies that a lipid is covalently attached to the carboxy‐terminal region of the S ‐layer glycoprotein, our data strongly support the conclusion that archaeosortase functions analogously to sortase, mediating proteolysis‐coupled, covalent cell surface attachment.