5oht
From Proteopedia
A GH31 family sulfoquinovosidase from E. coli in complex with aza-sugar inhibitor IFGSQ
Structural highlights
FunctionSQASE_ECOLI Catalyzes the hydrolysis of sulfoquinovosyl diacylglycerides (SQDG) to sulfoquinovose (SQ), which is then degraded by E.coli through the SQ Embden-Meyerhof-Parnas (SQ-EMP) sulfoglycolysis pathway as a source of carbon and sulfur. Therefore, is likely involved in the utilization of the sulfoquinovose headgroup found in ubiquitous plant sulfolipids. Is also able to hydrolyze simple sulfoquinovosides such as 1-sulfoquinovosylglycerol (SQGro). Is a retaining glycoside hydrolase, since it forms the alpha anomer of SQ (PubMed:26878550). Also exhibits some alpha-glucosidase activity against alpha-glucosyl fluoride in vitro, although natural substrates, such as alpha-glucobioses are scarcely hydrolyzed (PubMed:15294295).[1] [2] Publication Abstract from PubMedAn estimated 10 billion tonnes of sulfoquinovose (SQ) are produced and degraded each year. Prokaryotic sulfoglycolytic pathways catabolize sulfoquinovose (SQ) liberated from plant sulfolipid, or its delipidated form alpha-d-sulfoquinovosyl glycerol (SQGro), through the action of a sulfoquinovosidase (SQase), but little is known about the capacity of SQ glycosides to support growth. Structural studies of the first reported SQase (Escherichia coli YihQ) have identified three conserved residues that are essential for substrate recognition, but crossover mutations exploring active-site residues of predicted SQases from other organisms have yielded inactive mutants casting doubt on bioinformatic functional assignment. Here, we show that SQGro can support the growth of E. coli on par with d-glucose, and that the E. coli SQase prefers the naturally occurring diastereomer of SQGro. A predicted, but divergent, SQase from Agrobacterium tumefaciens proved to have highly specific activity toward SQ glycosides, and structural, mutagenic, and bioinformatic analyses revealed the molecular coevolution of catalytically important amino acid pairs directly involved in substrate recognition, as well as structurally important pairs distal to the active site. Understanding the defining features of SQases empowers bioinformatic approaches for mapping sulfur metabolism in diverse microbial communities and sheds light on this poorly understood arm of the biosulfur cycle. Structural and Biochemical Insights into the Function and Evolution of Sulfoquinovosidases.,Abayakoon P, Jin Y, Lingford JP, Petricevic M, John A, Ryan E, Wai-Ying Mui J, Pires DEV, Ascher DB, Davies GJ, Goddard-Borger ED, Williams SJ ACS Cent Sci. 2018 Sep 26;4(9):1266-1273. doi: 10.1021/acscentsci.8b00453. Epub, 2018 Sep 5. PMID:30276262[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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