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Maf ‐dependent bacterial flagellin glycosylation occurs before chaperone binding and flagellar T3SS export
Author(s) -
Parker Jennifer L.,
Lowry Rebecca C.,
Couto Narciso A. S.,
Wright Phillip C.,
Stafford Graham P.,
Shaw Jonathan G.
Publication year - 2014
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.12549
Subject(s) - flagellin , glycosylation , biology , chaperone (clinical) , secretion , microbiology and biotechnology , mutant , biochemistry , gene , medicine , pathology
Summary Bacterial swimming is mediated by rotation of a filament that is assembled via polymerization of flagellin monomers after secretion via a dedicated flagellar T ype III secretion system. Several bacteria decorate their flagellin with sialic acid related sugars that is essential for motility. A eromonas caviae is a model organism for this process as it contains a genetically simple glycosylation system and decorates its flagellin with pseudaminic acid ( Pse ). The link between flagellin glycosylation and export has yet to be fully determined. We examined the role of glycosylation in the export and assembly process in a strain lacking Maf1 , a protein involved in the transfer of Pse onto flagellin at the later stages of the glycosylation pathway. Immunoblotting, established that glycosylation is not required for flagellin export but is essential for filament assembly since non‐glycosylated flagellin is still secreted. Maf1 interacts directly with its flagellin substrate in vivo , even in the absence of pseudaminic acid. Flagellin glycosylation in a flagellin chaperone mutant ( flaJ ) indicated that glycosylation occurs in the cytoplasm before chaperone binding and protein secretion. Preferential chaperone binding to glycosylated flagellin revealed its crucial role, indicating that this system has evolved to favour secretion of the polymerization competent glycosylated form.