5E9W image
Entry Detail
PDB ID:
5E9W
Keywords:
Title:
Crystal structure of mRNA cap guanine-N7 methyltransferase obtained by limited proteolysis
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2015-10-15
Release Date:
2016-07-13
Method Details:
Experimental Method:
Resolution:
2.28 Å
R-Value Free:
0.25
R-Value Work:
0.22
R-Value Observed:
0.22
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:mRNA cap guanine-N7 methyltransferase
Chain IDs:A, B, C, D
Chain Length:312
Number of Molecules:4
Biological Source:Homo sapiens
Ligand Molecules
Primary Citation
Molecular basis of RNA guanine-7 methyltransferase (RNMT) activation by RAM.
Nucleic Acids Res. 44 10423 10436 (2016)
PMID: 27422871 DOI: 10.1093/nar/gkw637

Abstact

Maturation and translation of mRNA in eukaryotes requires the addition of the 7-methylguanosine cap. In vertebrates, the cap methyltransferase, RNA guanine-7 methyltransferase (RNMT), has an activating subunit, RNMT-Activating Miniprotein (RAM). Here we report the first crystal structure of the human RNMT in complex with the activation domain of RAM. A relatively unstructured and negatively charged RAM binds to a positively charged surface groove on RNMT, distal to the active site. This results in stabilisation of a RNMT lobe structure which co-evolved with RAM and is required for RAM binding. Structure-guided mutagenesis and molecular dynamics simulations reveal that RAM stabilises the structure and positioning of the RNMT lobe and the adjacent α-helix hinge, resulting in optimal positioning of helix A which contacts substrates in the active site. Using biophysical and biochemical approaches, we observe that RAM increases the recruitment of the methyl donor, AdoMet (S-adenosyl methionine), to RNMT. Thus we report the mechanism by which RAM allosterically activates RNMT, allowing it to function as a molecular rheostat for mRNA cap methylation.

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Primary Citation of related structures