Figure 1.

(A) Physical and genetic maps of the chromosomal regions surrounding R. sphaeroides and R. capsulatus cycY. Only cycY^Rs is physically linked to the ccoNOQP–ccoGHIS/rdxBHIS cluster required for the biosynthesis of the cbb₃-type Cyt c oxidase in both organisms (9, 30). Arrows and “T” refer to transcription direction and termination signal at the 3′ downstream region of cycY, respectively. (B) Sequence comparison of the 5′ upstream regions of cycY from R. capsulatus (RccycY), R. sphaeroides (RscycY), and P. denitrificans (PdcycM). Putative −35 (TTGAA) and −10 (TAg/cAT) regions for a σ⁷⁰-like promoter are indicated. Additional conserved elements of unknown significance (indicated by arrows) and putative ribosome binding sites rich in adenosine and guanine residues in the vicinity of the boxed translational start (ATG) codons also are shown.