大腸菌におけるtRNA分子の成熟過程

概要

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The post-transcriptional "maturation" process involved in the biosynthesis of tRNA is reviewed in the light of our recent finding on tRNA precursors and the mode of their enzymatic cleavage. A number of tRNA precursors were identified in a thermosensitive mutant of E. coli defective in RNase P and extensively characterized by fingerprinting and by in vitro cleaving reaction. These studies have revealed the following features of maturation process:<BR>(1) Many tRNA genes, if not all, are clustered in the E. coli genome and thus transcribed in multimeric precursor forms, although the tRNA gene clusters are rather scattered throughout the entire chromosome.<BR>(2) The multimeric precursors are cleaved by RNase O at the spacer regions into monomeric and/or dimeric forms, which are subsequently processed by RNase P at the 5 sides of the molecules into smaller monomeric forms. The monomeric intermediates are then trimmed at the 3 termini by RNase Q.<BR>(3) Modification of nucleotides seems to occur at distinct stages of maturation process, thereby indicating that modification and trimming reactions are somehow interrelated.
日本生物物理学会の論文