title: Metabolite profiling and peptidoglycan analysis of transient cell wall-deficient bacteria in a new Escherichia coli model system.
abstract: Many bacteria are able to assume a transient cell wall-deficient (or L-form) state under favourable osmotic conditions. Cell wall stress such as exposure to β-lactam antibiotics can enforce the transition to and maintenance of this state. L-forms actively proliferate and can return to the walled state upon removal of the inducing agent. We have adopted Escherichia coli as a model system for the controlled transition to and reversion from the L-form state, and have studied these dynamics with genetics, cell biology and 'omics' technologies. As such, a transposon mutagenesis screen underscored the requirement for the Rcs phosphorelay and colanic acid synthesis, while proteomics show only little differences between rods and L-forms. In contrast, metabolome comparison reveals the high abundance of lysophospholipids and phospholipids with unsaturated or cyclopropanized fatty acids in E. coli L-forms. This increase of membrane lipids associated with increased membrane fluidity may facilitate proliferation through bud formation. Visualization of the residual peptidoglycan with a fluorescently labelled peptidoglycan binding protein indicates de novo cell wall synthesis and a role for septal peptidoglycan synthesis during bud constriction. The DD-carboxypeptidases PBP5 and PBP6 are threefold and fourfold upregulated in L-forms, indicating a specific role for regulation of crosslinking during L-form proliferation.
authors.affiliation: Laboratory of Gene Technology, Department of Biosystems, KU Leuven, B-3001, Heverlee, Belgium; Laboratory of Food Microbiology, Department of Microbial and Molecular Systems, KU Leuven, B-3001, Heverlee, Belgium.
authors.forename: Alexander
authors.initials: A
authors.lastname: Cambré
authors.forename: Michael
authors.initials: M
authors.lastname: Zimmermann
authors.forename: Uwe
authors.initials: U
authors.lastname: Sauer
authors.forename: Bram
authors.initials: B
authors.lastname: Vivijs
authors.forename: William
authors.initials: W
authors.lastname: Cenens
authors.forename: Chris W
authors.initials: CW
authors.lastname: Michiels
authors.forename: Abram
authors.initials: A
authors.lastname: Aertsen
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Loessner
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Noben
authors.forename: Juan A
authors.initials: JA
authors.lastname: Ayala
authors.forename: Rob
authors.initials: R
authors.lastname: Lavigne
authors.forename: Yves
authors.initials: Y
authors.lastname: Briers
mesh_terms: D002473:Cell Wall / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D015723:Gene Library; D008563:Membrane Lipids / Q000378:metabolism*; D008954:Models, Biological; D046915:Penicillin-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D010457:Peptidoglycan / Q000378:metabolism*; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase / Q000096:biosynthesis / Q000235:genetics; D018440:beta-Lactam Resistance / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D029968:Escherichia coli Proteins; D008563:Membrane Lipids; C569173:PBP5 protein, E coli; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D047090:beta-Lactams; C569172:DacC protein, E coli; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase