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Publication Abstract from PubMed

2-O-alpha-Glucosylglycerol (GG) is a natural heteroside synthesized by many cyanobacteria and a few heterotrophic bacteria under salt stress conditions. Bacteria produce GG in response to stimuli and degrade it once the stimulus diminishes. Heterotrophic bacteria utilize GG phosphorylase (GGP), a member of the GH13_18 family, via a two-step process consisting of phosphorolysis and hydrolysis for GG catabolism. However, the precise mechanism by which GGP degrades GG remains elusive. We determined the 3D structure of a recently identified GGP (MsGGP) of the deep-sea bacterium Marinobacter salinexigens ZYF650(T), in complex with glucose and glycerol, alpha-d-glucose-1-phosphate (alphaGlc1-P), and orthophosphate (inorganic phosphate) at resolutions of 2.5, 2.7, and 2.7 A, respectively. Notably, the first alphaGlc1-P complex structure in the GH13_18 family, the complex of MsGGP and alphaGlc1-P, validates that GGP catalyzes GG decomposition through consecutive phosphorolysis and hydrolysis. In addition, the structure reveals the mechanism of high stereoselectivity on alphaGlc1-P. Glu231 and Asp190 were identified as the catalytic residues. Interestingly, these structures closely resemble each other, indicating minimal conformational changes upon binding end-product glucose and glycerol, or the intermediate alphaGlc1-P. The structures also indicate that the substrates may follow a specific trajectory and a precise order toward the active center in close proximity and in a geometrically favorable orientation for catalysis in a double displacement mechanism.

Structural basis of the bifunctionality of Marinobacter salinexigens ZYF650(T) glucosylglycerol phosphorylase in glucosylglycerol catabolism.,Lu D, Zhang K, Cheng C, Wu D, Yin L, Luo Q, Shi M, Ma H, Lu X J Biol Chem. 2025 Feb;301(2):108127. doi: 10.1016/j.jbc.2024.108127. Epub 2024 , Dec 25. PMID:39725037^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.