Nucleotide sequences of five maize chloroplast transfer RNA genes and their flanking regions.

Maize chloroplast tRNA genes encoding tRNA3Ser, tRNAPhe, tRNA2Thr, tRNA2Leu, and tRNAmMet, and their flanking regions have been sequenced. All five gene sequences show features commonly found in the few chloroplast tRNA genes sequenced so far; none of them encodes the 3'-terminal CCA triplet and none of them shows abnormal loop or stem lengths as seen in some genes for mammalian mitochondrial tRNAs. The 5'-flanking regions of some of these tRNA genes contain nucleotide stretches strongly homologous to -35 and -10 promoter regions of bacterial genes. Analysis of these conserved regions together with those seen in other plastid genes yields the consensus sequences ATTGANA at "-35" and TAAGAT at "-10." The 3'-flanking regions of some tRNA genes show dyad symmetries followed by a stretch of Thds. These and other regions may be involved in transcription termination or transcript processing.