PMID:19181804

Citation	Aktas, M and Narberhaus, F (2009) In vitro characterization of the enzyme properties of the phospholipid N-methyltransferase PmtA from Agrobacterium tumefaciens. J. Bacteriol. 191:2033-41
Abstract	Agrobacterium tumefaciens requires phosphatidylcholine (PC) in its membranes for plant infection. The phospholipid N-methyltransferase PmtA catalyzes all three transmethylation reactions of phosphatidylethanolamine (PE) to PC via the intermediates monomethylphosphatidylethanolamine (MMPE) and dimethylphosphatidylethanolamine (DMPE). The enzyme uses S-adenosylmethionine (SAM) as the methyl donor, converting it to S-adenosylhomocysteine (SAH). Little is known about the activity of bacterial Pmt enzymes, since PC biosynthesis in prokaryotes is rare. In this article, we present the purification and in vitro characterization of A. tumefaciens PmtA, which is a monomeric protein. It binds to PE, the intermediates MMPE and DMPE, the end product PC, and phosphatidylglycerol (PG) and phosphatidylinositol. Binding of the phospholipid substrates precedes binding of SAM. We used a coupled in vitro assay system to demonstrate the enzymatic activity of PmtA and to show that PmtA is inhibited by the end products PC and SAH and the antibiotic sinefungin. The presence of PG stimulates PmtA activity. Our study provides insights into the catalysis and control of a bacterial phospholipid N-methyltransferase.
Links	PubMed PMC2655499 Online version:10.1128/JB.01591-08
Keywords	Agrobacterium tumefaciens/chemistry; Agrobacterium tumefaciens/enzymology; Agrobacterium tumefaciens/genetics; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/isolation & purification; Bacterial Proteins/metabolism; Methyltransferases/chemistry; Methyltransferases/genetics; Methyltransferases/isolation & purification; Methyltransferases/metabolism; Phospholipids/metabolism; S-Adenosylhomocysteine/metabolism; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGRRK:B9J8G0		GO:0000773: phosphatidyl-N-methylethanolamine N-methyltransferase activity	ECO:0000314:		F		Figure 3 shows that in the absence of pmtA PE is not converted to PC by transmethylation reactions. While in the presence of pmtA it is converted to intermediates of the pathway and PC.	complete CACAO 4775
AGRRK:B9J8G0	enables	GO:0000773: phosphatidyl-N-methylethanolamine N-methyltransferase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
AGRT5:A9CKE9		GO:0008170: N-methyltransferase activity	ECO:0000314:		F		Fig. 3 shows PCR and RT-PCR. Shows that pmtA encodes phospholipid N-methyltransferase. Fig. 7 shows a smaller motility ability of the PC-deficient mutant (ΔpmtA Δpcs) compared to wildtype.	complete CACAO 5017

References

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