FIG. 1.

fnrN genes and proteins of R. etli. (A) Physical and genetic map of the R. etli fnrN genes. The positions of the potential Fnr target site sequences are indicated by open circles. The open arrows represent genes discussed in the text. The restriction sites used in subcloning for sequencing are shown, as follows: E, EcoRI; S, SacI; L, SalI; H, HindIII; R, EcoRV. (B) Alignment of the predicted amino acid sequences encoded by the fnrNchr and fnrNd genes from R. etli with the amino acid sequences of FnrN and FnrN2 from R. leguminosarum bv. viciae (GenBank accession no. AA86478 and AAB58263, respectively) and Fnr from E. coli (GenBank accession no. P03019). The four cysteine residues probably involved in oxygen sensing are indicated by boldface type and underlining. The helix-turn-helix motif is enclosed in a box.