1k98
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(New page: 200px<br /><applet load="1k98" size="450" color="white" frame="true" align="right" spinBox="true" caption="1k98, resolution 3.75Å" /> '''AdoMet complex of Me...)
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Revision as of 16:51, 20 November 2007
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AdoMet complex of MetH C-terminal fragment
Overview
B(12)-dependent methionine synthase (MetH) from Escherichia coli is a, large modular protein that uses bound cobalamin as an intermediate methyl, carrier. Major domain rearrangements have been postulated to explain how, cobalamin reacts with three different substrates: homocysteine, methyltetrahydrofolate and S-adenosylmethionine (AdoMet). Here we describe, the 3.0 A structure of a 65 kDa C-terminal fragment of MetH that spans the, cobalamin- and AdoMet-binding domains, arranged in a conformation suitable, for the methyl transfer from AdoMet to cobalamin that occurs during, activation. In the conversion to the activation conformation, a helical, domain that capped the cofactor moves 26 A and rotates by 63 degrees, allowing formation of a new interface between cobalamin and the, AdoMet-binding (activation) domain. Interactions with the MetH activation, domain drive the cobalamin away from its binding domain in a way that, requires dissociation of the axial cobalt ligand and, thereby, provide a, mechanism for control of the distribution of enzyme conformations.
About this Structure
1K98 is a Single protein structure of sequence from Escherichia coli with SO4 and B12 as ligands. Active as Methionine synthase, with EC number 2.1.1.13 Full crystallographic information is available from OCA.
Reference
Domain alternation switches B(12)-dependent methionine synthase to the activation conformation., Bandarian V, Pattridge KA, Lennon BW, Huddler DP, Matthews RG, Ludwig ML, Nat Struct Biol. 2002 Jan;9(1):53-6. PMID:11731805
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