This enzyme, from the marine cyanobacterium Synechococcus sp. WH8102, differs from EC 184.108.40.206, sarcosine/dimethylglycine N-methyltransferase in that it cannot use sarcosine as an alternative substrate . Betaine is a ’compatible solute’ that enables cyanobacteria to cope with osmotic stress by maintaining a positive cellular turgor.
Lu, W.D., Chi, Z.M. and Su, C.D. Identification of glycine betaine as compatible solute in Synechococcus sp. WH8102 and characterization of its N-methyltransferase genes involved in betaine synthesis. Arch. Microbiol.186 (2006) 495–506. [PMID: 17019606]