6SJS image
Entry Detail
PDB ID:
6SJS
Keywords:
Title:
Methyltransferase of the MtgA N227A mutant from Desulfitobacterium hafniense in complex with methyl-tetrahydrofolate
Biological Source:
PDB Version:
Deposition Date:
2019-08-13
Release Date:
2019-09-25
Method Details:
Experimental Method:
Resolution:
1.80 Å
R-Value Free:
0.21
R-Value Work:
0.17
R-Value Observed:
0.18
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Tetrahydromethanopterin S-methyltransferase
Mutations:N227A
Chain IDs:A, B
Chain Length:307
Number of Molecules:2
Biological Source:Desulfitobacterium hafniense DCB-2
Primary Citation
Structures in Tetrahydrofolate Methylation in Desulfitobacterial Glycine Betaine Metabolism at Atomic Resolution.
Chembiochem 21 776 779 (2020)
PMID: 31518049 DOI: 10.1002/cbic.201900515

Abstact

Enzymes orchestrating methylation between tetrahydrofolate (THF) and cobalamin (Cbl) are abundant among all domains of life. During energy production in Desulfitobacterium hafniense, MtgA catalyzes the methyl transfer from methylcobalamin (Cbl-CH3) to THF in the catabolism of glycine betaine (GB). Despite its lack of sequence identity with known structures, we could show that MtgA forms a homodimeric complex of two TIM barrels. Atomic crystallographic insights into the interplay of MtgA with THF as well as analysis of a trapped reaction intermediate (THF-CH3)+ reveal conformational rearrangements during the transfer reaction. Whereas residues for THF methylation are conserved, the binding mode for the THF glutamyl-p-aminobenzoate moiety (THF tail) is unique. Apart from snapshots of individual reaction steps of MtgA, structure-based mutagenesis combined with enzymatic activity assays allowed a mechanistic description of the methyl transfer between Cbl-CH3 and THF. Altogether, the THF-tail-binding motion observed in MtgA is unique compared to other THF methyltransferases and therefore contributes to the general understanding of THF-mediated methyl transfer.

Legend

Protein

Chemical

Disease

Primary Citation of related structures