5VOO image
Entry Detail
PDB ID:
5VOO
Keywords:
Title:
Methionine synthase folate-binding domain with methyltetrahydrofolate from Thermus thermophilus HB8
Biological Source:
PDB Version:
Deposition Date:
2017-05-03
Release Date:
2018-01-17
Method Details:
Experimental Method:
Resolution:
2.40 Å
R-Value Free:
0.22
R-Value Work:
0.19
R-Value Observed:
0.19
Space Group:
P 61 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:5-methyltetrahydrofolate homocysteine S-methyltransferase
Chain IDs:A, B, C, D, E, F
Chain Length:296
Number of Molecules:6
Biological Source:Thermus thermophilus (strain HB8 / ATCC 27634 / DSM 579)
Primary Citation
The folate-binding module of Thermus thermophilus cobalamin-dependent methionine synthase displays a distinct variation of the classical TIM barrel: a TIM barrel with a `twist'.
Acta Crystallogr D Struct Biol 74 41 51 (2018)
PMID: 29372898 DOI: 10.1107/S2059798317018290

Abstact

Methyl transfer between methyltetrahydrofolate and corrinoid molecules is a key reaction in biology that is catalyzed by a number of enzymes in many prokaryotic and eukaryotic organisms. One classic example of such an enzyme is cobalamin-dependent methionine synthase (MS). MS is a large modular protein that utilizes an SN2-type mechanism to catalyze the chemically challenging methyl transfer from the tertiary amine (N5) of methyltetrahydrofolate to homocysteine in order to form methionine. Despite over half a century of study, many questions remain about how folate-dependent methyltransferases, and MS in particular, function. Here, the structure of the folate-binding (Fol) domain of MS from Thermus thermophilus is reported in the presence and absence of methyltetrahydrofolate. It is found that the methyltetrahydrofolate-binding environment is similar to those of previously described methyltransferases, highlighting the conserved role of this domain in binding, and perhaps activating, the methyltetrahydrofolate substrate. These structural studies further reveal a new distinct and uncharacterized topology in the C-terminal region of MS Fol domains. Furthermore, it is found that in contrast to the canonical TIM-barrel β8α8 fold found in all other folate-binding domains, MS Fol domains exhibit a unique β8α7 fold. It is posited that these structural differences are important for MS function.

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