RodZ and PgsA Play Intertwined Roles in Membrane Homeostasis ofBacillus subtilisand Resistance to Weak Organic Acid Stress.
Weak organic acids like sorbic and acetic acid are widely used to prevent growth of spoilage organisms such as Bacilli. To identify genes involved in weak acid stress tolerance we screened a transposon mutant library ofBacillus subtilisfor sorbic acid sensitivity. Mutants of therodZ(ymfM) gene were found to be hypersensitive to the lipophilic weak organic acid. RodZ is involved in determining the cell's rod-shape and believed to interact with the bacterial actin-like MreB cytoskeleton. SincerodZlies upstream in the genome of the essential genepgsA(phosphatidylglycerol phosphate synthase) we hypothesized that expression of the latter might also be affected inrodZmutants and hence contribute to the phenotype observed. We show that both genes are co-transcribed and that both therodZ::mini-Tn10mutant and a conditionalpgsAmutant, under conditions of minimalpgsAexpression, were sensitive to sorbic and acetic acid. Both strains displayed a severely altered membrane composition. Compared to the wild-type strain, phosphatidylglycerol and cardiolipin levels were lowered and the average acyl chain length was elongated. Induction ofrodZexpression from a plasmid in our transposon mutant led to no recovery of weak acid susceptibility comparable to wild-type levels. However,pgsAoverexpression in the same mutant partly restored sorbic acid susceptibility and fully restored acetic acid sensitivity. A construct containing bothrodZandpgsAas on the genome led to some restored growth as well. We propose that RodZ and PgsA play intertwined roles in membrane homeostasis and tolerance to weak organic acid stress.
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Johan
J
van Beilen
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Christoph J
CJ
Blohmke
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Hendrik
H
Folkerts
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Richard
R
de Boer
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Anna
A
Zakrzewska
Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands.
Wim
W
Kulik
Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands.
Fred M
FM
Vaz
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Stanley
S
Brul
Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.
Alexander
A
Ter Beek
Bacillus subtilis; acetic acid; membrane compositional fluctuations; pgs A; rod Z; sorbic acid; weak organic acids