title: Expression and physiological relevance of Agrobacterium tumefaciens phosphatidylcholine biosynthesis genes.
abstract: Phosphatidylcholine (PC), or lecithin, is the major phospholipid in eukaryotic membranes, whereas only 10% of all bacteria are predicted to synthesize PC. In Rhizobiaceae, including the phytopathogenic bacterium Agrobacterium tumefaciens, PC is essential for the establishment of a successful host-microbe interaction. A. tumefaciens produces PC via two alternative pathways, the methylation pathway and the Pcs pathway. The responsible genes, pmtA (coding for a phospholipid N-methyltransferase) and pcs (coding for a PC synthase), are located on the circular chromosome of A. tumefaciens C58. Recombinant expression of pmtA and pcs in Escherichia coli revealed that the individual proteins carry out the annotated enzyme functions. Both genes and a putative ABC transporter operon downstream of PC are constitutively expressed in A. tumefaciens. The amount of PC in A. tumefaciens membranes reaches around 23% of total membrane lipids. We show that PC is distributed in both the inner and outer membranes. Loss of PC results in reduced motility and increased biofilm formation, two processes known to be involved in virulence. Our work documents the critical importance of membrane lipid homeostasis for diverse cellular processes in A. tumefaciens.
authors.affiliation: Microbial Biology, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Klüsener
authors.forename: Meriyem
authors.initials: M
authors.lastname: Aktas
authors.forename: Kai M
authors.initials: KM
authors.lastname: Thormann
authors.forename: Mirja
authors.initials: M
authors.lastname: Wessel
authors.forename: Franz
authors.initials: F
authors.lastname: Narberhaus
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D054709:Lecithins / Q000096:biosynthesis*; D050941:Phosphatidyl-N-Methylethanolamine N-Methyltransferase / Q000235:genetics / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D054709:Lecithins; D050941:Phosphatidyl-N-Methylethanolamine N-Methyltransferase; D017855:Transferases (Other Substituted Phosphate Groups); C483298:CDP-diacylglycerol choline O-phosphatidyltransferase; D002794:Choline