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Virulence of Agrobacterium tumefaciens requires lipid homeostasis mediated by the lysyl‐phosphatidylglycerol hydrolase AcvB
Author(s) -
Groenewold Maike K.,
Hebecker Stefanie,
Fritz Christiane,
Czolkoss Simon,
Wiesselmann Milan,
Heinz Dirk W.,
Jahn Dieter,
Narberhaus Franz,
Aktas Meriyem,
Moser Jürgen
Publication year - 2019
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.14154
Subject(s) - biology , agrobacterium tumefaciens , complementation , biochemistry , phosphatidylglycerol , agrobacterium , virulence , virulence factor , microbiology and biotechnology , transformation (genetics) , gene , phospholipid , phenotype , membrane , phosphatidylcholine
Summary Agrobacterium tumefaciens transfers oncogenic T‐DNA via the type IV secretion system (T4SS) into plants causing tumor formation. The acvB gene encodes a virulence factor of unknown function required for plant transformation. Here we specify AcvB as a periplasmic lysyl‐phosphatidylglycerol (L‐PG) hydrolase, which modulates L‐PG homeostasis. Through functional characterization of recombinant AcvB variants, we showed that the C‐terminal domain of AcvB (residues 232–456) is sufficient for full enzymatic activity and defined key residues for catalysis. Absence of the hydrolase resulted in ~10‐fold increase in L‐PG in Agrobacterium membranes and abolished T‐DNA transfer and tumor formation. Overproduction of the L‐PG synthase gene ( lpiA ) in wild‐type A . tumefaciens resulted in a similar increase in the L‐PG content (~7‐fold) and a virulence defect even in the presence of intact AcvB. These results suggest that elevated L‐PG amounts (either by overproduction of the synthase or absence of the hydrolase) are responsible for the virulence phenotype. Gradually increasing the L‐PG content by complementation with different acvB variants revealed that cellular L‐PG levels above 3% of total phospholipids interfere with T‐DNA transfer. Cumulatively, this study identified AcvB as a novel virulence factor required for membrane lipid homeostasis and T‐DNA transfer.