Homocysteine S-methyltransferases (HMTs, EC 2.1.1.0) catalyse the conversion of homocysteine to methionine using S-methylmethionine or S-adenosylmethionine as the methyl donor. HMTs play an important role in methionine biosynthesis and are widely distributed among micro-organisms, plants and animals. Additionally, HMTs play a role in metabolite repair of S-adenosylmethionine by removing an inactive diastereomer from the pool. The mmuM gene product from Escherichia coli is an archetypal HMT family protein and contains a predicted zinc-binding motif in the enzyme active site. In the present study, we demonstrate X-ray structures for MmuM in oxidized, apo and metallated forms, representing the first such structures for any member of the HMT family. The structures reveal a metal/substrate-binding pocket distinct from those in related enzymes. The presented structure analysis and modelling of co-substrate interactions provide valuable insight into the function of MmuM in both methionine biosynthesis and cofactor repair.
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February 2016
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Point scanning confocal microscopic imaging of C2C12 undifferentiatedmyoblasts (top panels) and differentiatedmultinucleated myotubes (bottom panels) immunofluorescently labelled with DAPI (blue) PDLIM7 (green) and Phalloidin or Nedd4-1 (red). Merged images show co-localization of PDLIM7 and Phalloidin decreases with myotube formation (left panels) and co-location of PDLIM7 and Nedd4-1 increases with myotube formation (right panels). Image courtesy of Robert D’Cruz et al. (for further details see pages 267–276).Close Modal - PDF Icon PDF LinkFront Matter
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Research Article|
January 25 2016
Crystal structure of the homocysteine methyltransferase MmuM from Escherichia coli
Kunhua Li
;
Kunhua Li
*Department of Chemistry, University of Florida, Gainesville, FL 32611, U.S.A.
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Gengnan Li
;
Gengnan Li
*Department of Chemistry, University of Florida, Gainesville, FL 32611, U.S.A.
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Louis M.T. Bradbury
;
Louis M.T. Bradbury
1
†Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A.
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Andrew D. Hanson
;
Andrew D. Hanson
†Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A.
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Steven D. Bruner
Steven D. Bruner
2
*Department of Chemistry, University of Florida, Gainesville, FL 32611, U.S.A.
2To whom correspondence should be addressed (email bruner@ufl.edu).
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Biochem J (2016) 473 (3): 277–284.
Article history
Received:
September 10 2015
Revision Received:
November 10 2015
Accepted:
November 12 2015
Accepted Manuscript online:
November 12 2015
Citation
Kunhua Li, Gengnan Li, Louis M.T. Bradbury, Andrew D. Hanson, Steven D. Bruner; Crystal structure of the homocysteine methyltransferase MmuM from Escherichia coli. Biochem J 1 February 2016; 473 (3): 277–284. doi: https://doi.org/10.1042/BJ20150980
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