ANALYSIS OF THE ESCHERICHIA-COLI GENOME .4. DNA-SEQUENCE OF THE REGION FROM 89.2 TO 92.8 MINUTES

We present the sequence of 176 kilobases of the Escherichia coli K-12 genome, from katG at 89.2 to an open reading frame (ORF) of unknown fu nction at 92.8 minutes on the genetic map. This brings the total of co ntiguous sequence from the E.coli genome project to 500 kb (81.5 to 92 .8 minutes). This segment contains 134 putative coding genes (ORFs) of which 66 genes were previously identified. Eight new genes-acs, pepE, and nrfB-G-were identified as well as the previously mapped gldA and air genes. Still, 58 ORFs remain unidentified despite literature and s imilarity searches. The arrangement of proposed genes relative to poss ible promoters and terminators suggests 55 potential transcription uni ts. Other features include 13 REP elements, one IRU (ERIC) repeat, 59 computer-predicted bends, 42 Chi sites and one new grey hole. Sixteen signal peptides were found, including those of lamB, btuB, and malE. T wo ribosomal RNA loci, rrnB and rrnE, are located in this segment, so we have now sequenced four of the seven E.coli rRNA loci. Comparison o f the rRNA loci reveals some differences in the ribosomal structural R NAs which are generally compatible with the proposed secondary structu res.