Cleavage of mitochondria-like transfer RNAs expressed in Escherichia coli

Mitochondrial (mt) transfer RNAs (tRNAs) often harbor unusual structural features causing their secondary structure to differ from the conventional cloverleaf, tRNAs designed with such irregularities, termed mt-like tRNAs, are active in Escherichia as suppressors of reporter genes, although they display low steady-state levels. Characterization of fragments produced during mt-like tRNA processing in vitro and in vivo suggests that these RNAs are not fully processed at their 5 ' ends and are cleaved internally. These abnormal processing events may account for the low levels of mature mt-like RNAs in vivo and are most likely related to defective processing by RNase P. (C) 2001 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.