Mannosylglucosylglycerate biosynthesis in the deep-branching phylum Planctomycetes: characterization of the uncommon enzymes from Rhodopirellula baltica.
The biosynthetic pathway for the rare compatible solute mannosylglucosylglycerate (MGG) accumulated by Rhodopirellula baltica, a marine member of the phylum Planctomycetes, has been elucidated. Like one of the pathways used in the thermophilic bacterium Petrotoga mobilis, it has genes coding for glucosyl-3-phosphoglycerate synthase (GpgS) and mannosylglucosyl-3-phosphoglycerate (MGPG) synthase (MggA). However, unlike Ptg. mobilis, the mesophilic R. baltica uses a novel and very specific MGPG phosphatase (MggB). It also lacks a key enzyme of the alternative pathway in Ptg. mobilis - the mannosylglucosylglycerate synthase (MggS) that catalyses the condensation of glucosylglycerate with GDP-mannose to produce MGG. The R. baltica enzymes GpgS, MggA, and MggB were expressed in E. coli and characterized in terms of kinetic parameters, substrate specificity, temperature and pH dependence. This is the first characterization of genes and enzymes for the synthesis of compatible solutes in the phylum Planctomycetes and for the synthesis of MGG in a mesophile.
Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal.
Sofia
S
Cunha
Ana Filipa
AF
d'Avó
Ana
A
Mingote
Pedro
P
Lamosa
Milton S
MS
da Costa
Joana
J
Costa
D001203:Ascomycota / Q000201:enzymology*; D004187:Disaccharides / Q000737:chemistry* / Q000378:metabolism*; D004789:Enzyme Activation; D004795:Enzyme Stability; D005988:Glyceric Acids / Q000737:chemistry* / Q000378:metabolism*; D006867:Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
D004187:Disaccharides; D005988:Glyceric Acids; C522541:mannopyranosyl-1-2-glucopyranosyl-1-2-glycerate; D006867:Hydrolases