Crystal structure of tRNA(m1G37)methyltransferase: insights into tRNA recognition.
tRNA(m(1)G37)methyltransferase (TrmD) catalyzes the transfer of a methyl group from S-adenosyl-L- methionine (AdoMet) to G(37) within a subset of bacterial tRNA species, which have a G residue at the 36th position. The modified guanosine is adjacent to and 3' of the anticodon and is essential for the maintenance of the correct reading frame during translation. Here we report four crystal structures of TrmD from Haemophilus influenzae, as binary complexes with either AdoMet or S-adenosyl-L-homocysteine (AdoHcy), as a ternary complex with AdoHcy and phosphate, and as an apo form. This first structure of TrmD indicates that it functions as a dimer. It also suggests the binding mode of G(36)G(37) in the active site of TrmD and the catalytic mechanism. The N-terminal domain has a trefoil knot, in which AdoMet or AdoHcy is bound in a novel, bent conformation. The C-terminal domain shows structural similarity to trp repressor. We propose a plausible model for the TrmD(2)-tRNA(2) complex, which provides insights into recognition of the general tRNA structure by TrmD.
Ahn
Hyung Jun
HJ
Structural Proteomics Laboratory, School of Chemistry and Molecular Engineering, Seoul National University, Seoul 151-742, Korea.
Kim
Hyeon-Woo
HW
Yoon
Hye-Jin
HJ
Lee
Byung Il
BI
Suh
Se Won
SW
Yang
Jin Kuk
JK
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D019281:Dimerization; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D012359:tRNA Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D046911:Macromolecular Substances; D012329:RNA, Bacterial; D012436:S-Adenosylmethionine; D012343:RNA, Transfer; D012359:tRNA Methyltransferases; C036950:tRNA (guanine-N1-)-methyltransferase