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5GWX

Crystal structure of glycine sarcosine N-methyltransferase from Methanohalophilus portucalensis in complex with S-adenosylmethionine and sarcosine

Summary for 5GWX
Entry DOI10.2210/pdb5gwx/pdb
DescriptorGlycine sarcosine N-methyltransferase, S-ADENOSYLMETHIONINE, SARCOSINE, ... (5 entities in total)
Functional Keywordss-adenosylmethionine-dependent methyltransferases, sam, adomet-mtase, class i monomethylation, glycine, sarcosine rate-limiting enzyme, betaine biosynthesis betaine-mediated feedback inhibition, transferase
Biological sourceMethanohalophilus portucalensis FDF-1
Total number of polymer chains1
Total formula weight33536.09
Authors
Lee, Y.R.,Lin, T.S.,Lai, S.J.,Liu, M.S.,Lai, M.C.,Chan, N.L. (deposition date: 2016-09-14, release date: 2016-11-23, Last modification date: 2023-11-08)
Primary citationLee, Y.R.,Lin, T.S.,Lai, S.J.,Liu, M.S.,Lai, M.C.,Chan, N.L.
Structural Analysis of Glycine Sarcosine N-methyltransferase from Methanohalophilus portucalensis Reveals Mechanistic Insights into the Regulation of Methyltransferase Activity.
Sci Rep, 6:38071-38071, 2016
Cited by
PubMed Abstract: Methyltransferases play crucial roles in many cellular processes, and various regulatory mechanisms have evolved to control their activities. For methyltransferases involved in biosynthetic pathways, regulation via feedback inhibition is a commonly employed strategy to prevent excessive accumulation of the pathways' end products. To date, no biosynthetic methyltransferases have been characterized by X-ray crystallography in complex with their corresponding end product. Here, we report the crystal structures of the glycine sarcosine N-methyltransferase from the halophilic archaeon Methanohalophilus portucalensis (MpGSMT), which represents the first structural elucidation of the GSMT methyltransferase family. As the first enzyme in the biosynthetic pathway of the osmoprotectant betaine, MpGSMT catalyzes N-methylation of glycine and sarcosine, and its activity is feedback-inhibited by the end product betaine. A structural analysis revealed that, despite the simultaneous presence of both substrate (sarcosine) and cofactor (S-adenosyl-L-homocysteine; SAH), the enzyme was likely crystallized in an inactive conformation, as additional structural changes are required to complete the active site assembly. Consistent with this interpretation, the bound SAH can be replaced by the methyl donor S-adenosyl-L-methionine without triggering the methylation reaction. Furthermore, the observed conformational state was found to harbor a betaine-binding site, suggesting that betaine may inhibit MpGSMT activity by trapping the enzyme in an inactive form. This work implicates a structural basis by which feedback inhibition of biosynthetic methyltransferases may be achieved.
PubMed: 27934872
DOI: 10.1038/srep38071
PDB entries with the same primary citation
Experimental method
X-RAY DIFFRACTION (2.205 Å)
Structure validation

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