5E8J

Crystal structure of mRNA cap guanine-N7 methyltransferase in complex with RAM

Summary for 5E8J

• Entry DOI: 10.2210/pdb5e8j/pdb
• Related: 3BGV 3EPP
• Descriptor: mRNA cap guanine-N7 methyltransferase, RNMT-activating mini protein, GLYCEROL, ... (5 entities in total)
• Functional Keywords: mrna capping, mrna processing, translation
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 4
• Total formula weight: 84776.59

Authors

Petit, P.,Cowling, V. (deposition date: 2015-10-14, release date: 2016-07-13, Last modification date: 2024-01-10)

Primary citation

Varshney, D.,Petit, A.P.,Bueren-Calabuig, J.A.,Jansen, C.,Fletcher, D.A.,Peggie, M.,Weidlich, S.,Scullion, P.,Pisliakov, A.V.,Cowling, V.H.
Molecular basis of RNA guanine-7 methyltransferase (RNMT) activation by RAM.
Nucleic Acids Res., 44:10423-10436, 2016

PubMed Abstract: 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.

PubMed: 27422871
DOI: 10.1093/nar/gkw637

Experimental method

X-RAY DIFFRACTION (2.35 Å)