Structure of crystalline Escherichia coli methionyl-tRNA(f)Met formyltransferase: comparison with glycinamide ribonucleotide formyltransferase.
Formylation of the methionyl moiety esterified to the 3' end of tRNA(f)Met is a key step in the targeting of initiator tRNA towards the translation start machinery in prokaryotes. Accordingly, the presence of methionyl-tRNA(f)Met formyltransferase (FMT), the enzyme responsible for this formylation, is necessary for the normal growth of Escherichia coli. The present work describes the structure of crystalline E.coli FMT at 2.0 A, resolution. The protein has an N-terminal domain containing a Rossmann fold. This domain closely resembles that of the glycinamide ribonucleotide formyltransferase (GARF), an enzyme which, like FMT, uses N-10 formyltetrahydrofolate as formyl donor. However, FMT can be distinguished from GARF by a flexible loop inserted within its Rossmann fold. In addition, FMT possesses a C-terminal domain with a beta-barrel reminiscent of an OB fold. This latter domain provides a positively charged side oriented towards the active site. Biochemical evidence is presented for the involvement of these two idiosyncratic regions (the flexible loop in the N-terminal domain, and the C-terminal domain) in the binding of the tRNA substrate.
Schmitt
E
E
Laboratoire de Biochimie, Unité de Recherche Associëe no.1970 du Centre National de la Recherche Scientifique, Palaiseau, France.
Blanquet
S
S
Mechulam
Y
Y
D000217:Acyltransferases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D003460:Crystallization; D004926:Escherichia coli / Q000201:enzymology*; D019877:Hydroxymethyl and Formyl Transferases; D008969:Molecular Sequence Data; D051026:Phosphoribosylglycinamide Formyltransferase; D011485:Protein Binding; D011487:Protein Conformation; D012343:RNA, Transfer / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D012343:RNA, Transfer; D019877:Hydroxymethyl and Formyl Transferases; D051026:Phosphoribosylglycinamide Formyltransferase; C021561:methionyl-tRNA formyltransferase; D000217:Acyltransferases