7LL3 image
Entry Detail
PDB ID:
7LL3
Keywords:
Title:
S-adenosylmethionine synthetase co-crystallized with UppNHp
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2021-02-03
Release Date:
2021-03-31
Method Details:
Experimental Method:
Resolution:
2.24 Å
R-Value Free:
0.23
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 61 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:S-adenosylmethionine synthase
Chain IDs:A, B
Chain Length:384
Number of Molecules:2
Biological Source:Escherichia coli 908573
Primary Citation
Substrate Dynamics Contribute to Enzymatic Specificity in Human and Bacterial Methionine Adenosyltransferases.
Jacs Au 1 2349 2360 (2021)
PMID: 34977903 DOI: 10.1021/jacsau.1c00464

Abstact

Protein conformational changes can facilitate the binding of noncognate substrates and underlying promiscuous activities. However, the contribution of substrate conformational dynamics to this process is comparatively poorly understood. Here, we analyze human (hMAT2A) and Escherichia coli (eMAT) methionine adenosyltransferases that have identical active sites but different substrate specificity. In the promiscuous hMAT2A, noncognate substrates bind in a stable conformation to allow catalysis. In contrast, noncognate substrates sample stable productive binding modes less frequently in eMAT owing to altered mobility in the enzyme active site. Different cellular concentrations of substrates likely drove the evolutionary divergence of substrate specificity in these orthologues. The observation of catalytic promiscuity in hMAT2A led to the detection of a new human metabolite, methyl thioguanosine, that is produced at elevated levels in a cancer cell line. This work establishes that identical active sites can result in different substrate specificity owing to the effects of substrate and enzyme dynamics.

Legend

Protein

Chemical

Disease

Primary Citation of related structures