PrmC/RF1 complex (E. coli)

Gln methyltransferase (PrmC) / Translation termination (RF1)
(JPEG)
Ribbon Representation of the PrmC-RF1 Complex (A) and Detailed View of the PrmC Active Site (B) (A) The PrmC Nter and Cter domains and the linker connecting these two domains are shown in green, blue, and cyan, and the RF1 domains 1, 2, 3, and 4 are colored yellow, pink, orange, and red, respectively. AdoHCy and the RF1 residue Gln 235 side chain are shown as sticks. The AdoHCy sulfur atom is colored green. The GGQ motif and the PAT anticodon loop from RF1 are in gray and green, respectively. (B) Stereo view representation of RF1 Gln 235 interactions with PrmC. The C_ traces of PrmC Nter, linker, and Cter domains and RF1 domain 3 are shown in green, blue, gray, and orange, respectively. The PrmC side chain residues and AdoHCy are colored in blue and yellow, respectively. RF1 Gln 235 is in orange. The AdoMet methyl group to be transferred to Gln 235 is modeled by a gray sphere. Hydrogen bonds are indicated by red dashed lines. The distance between the Gln 235 N_2 atom and the AdoMet methyl group is shown as black dashed lines. The 2Fo-Fc electron density contoured at 1_ is depicted around the AdoHCy cofactor, and the RF1 Gln 235 side chain is shown in violet.
Function Gln methyltransferase (PrmC) / Translation termination (RF1)
Fold _/_ fold(PrmC) / multi-domain protein (_ and _) (RF1)
Resolution 3.1
Remarks S-adenosylhomocysteine
PDN code 2B3T
Reference Graille, M., Heurgué-Hamard, V., Champ, S., Mora, L., Scrima, N., Ulryck, N., van Tilbeurgh, H., Buckingham, R.H. Molecular Basis for Bacterial Class I Release Factor Methylation by PrmC Mol.Cell v20 pp.917-927 , 2005 Full text

Class I release factors bind to ribosomes in response to stop codons and trigger peptidyl-tRNA hydrolysis at the P site. Prokaryotic and eukaryotic RFs share one motif: a GGQ tripeptide positioned in a loop at the end of a stem region that interacts with the ribosomal peptidyl transferase center. The glutamine side chain of this motif is specifically methylated in both prokaryotes and eukaryotes. Methylation in E. coli is due to PrmC and results in strong stimulation of peptide chain release. We have solved the crystal structure of the complex between E. coli RF1 and PrmC bound to the methyl donor product AdoHCy. Both the GGQ domain (domain 3) and the central region (domains 2 and 4) of RF1 interact with PrmC. Structural and mutagenic data indicate a compact conformation of RF1 that is unlike its conformation when it is bound to the ribosome but is similar to the crystal structure of the protein alone.