FIG. 4.

Organization of the putative nos operon in different streptococci, as determined by sequences from their completed and unfinished microbial genome databases (http://www.ncbi.nih.gov). The nosX genes in the mitis group (S. gordonii, S. pneumoniae, and S. mitis), S. mutans, and S. agalactiae are contiguous with qor1 and qor2, whereas only the nosX gene was identified in S. pyogenes. In S. mutans, S. agalactiae, and S. pyogenes, an additional ORF located upstream of nosX is transcribed in the same direction and encodes an oxalocrotonate tautomerase. ORFs transcribed in the same direction as nosX are shown in grey.