MettRNA

MettRNA is a term encountered in some discussions of transfer RNA biology, used as a shorthand for methionyl-tRNA (tRNA^Met), the tRNA charged with the amino acid methionine. In formal nomenclature, the molecule is referred to as tRNA^Met, with organism-specific isoacceptors that recognize methionine coding signals during translation. The name MettRNA is not a standard or widely adopted designation in primary literature, but it may appear in reviews or discussions to emphasize the methionine-carrying function of this tRNA.

Structure and charging

Like other tRNAs, tRNA^Met adopts the characteristic cloverleaf and laterally H-shaped three-dimensional fold, featuring an acceptor stem for aminoacylation, a D loop, an anticodon loop, and a TΨC loop. It is charged with methionine by methionyl-tRNA synthetase, ensuring that methionine is available for incorporation into nascent polypeptides. In many organisms, there are separate roles for the methionyl-tRNA used to initiate translation and for those used during elongation, with initiator and elongator tRNA species differing in certain sequence and structural features.

Function and biology

The primary role of tRNA^Met (and thus of MettRNA in shorthand) is to deliver methionine to the ribosome. In bacteria, initiation often involves a formylated initiator methionyl-tRNA, whereas eukaryotes and archaea use a non-formylated initiator methionyl-tRNA. Variants and post-transcriptional modifications of tRNA^Met contribute to accuracy and efficiency of translation.

Research context

In synthetic biology and genetic research, tRNA^Met is sometimes manipulated to study initiation control, codon reassignment, or tolerance to amino acid substitutions. Terminology varies, and MettRNA remains informal shorthand rather than a formal class of molecules.

See also: tRNA, methionyl-tRNA synthetase, tRNA^Met, initiation tRNA, elongation tRNA.