FIG. 2.

Linear orientation of the gene cluster of MR-1 from omcA downstream, as derived from the preliminary genomic sequence data provided by The Institute for Genomic Research (http://www.tigr.org). The diagram is drawn to scale, and the transcription direction for all genes is from left to right (5′ → 3′). The relative positions of some of the ORFs and complementing fragments are indicated at the bottom; position 1 corresponded to the first base of the start codon of omcA. The solid boxes below the gene cluster indicate the DNA fragments used in complementation studies. omcA and omcB encode OM cytochromes involved in Mn(IV) reduction (32, 34), while mtrA and mtrB have putative roles in metal reduction (2, 3). Other possible ORFs (orf1 through orf9 and altA) with some sequence homology to known genes from other species are also shown. The best matches to these ORFs, as identified by BLAST analysis, are shown in Table 3.