This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1k98
From Proteopedia
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. 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 Page seeded by OCA on Fri May 2 22:27:47 2008
