Fig. 4
Physical arrangements of the chemotaxis gene clusters in the complete genomes of the 5 strains. A, the gene clusters possessed by the crystalline Fe (III) oxide- and sulfur-stimulated strains; B, the gene clusters possessed by the anode-stimulated strains. Red- and black-colored strain names in A as well as the blue-colored strain names in B show those strains stimulated by using the crystalline Fe (III) oxide, sulfur and anode as the electron acceptors, respectively. Different colors show the chemotaxis genes of cheA (red) coding for an autophosphorylating histidine kinase, cheB (champagne) for a methylesterase, cheC (pink) for a protein phosphatase, cheD (maroon) for a chemoreceptor glutamine deamidase, cheR (baby blue) for a methyltransferase, cheW (blue) for a scaffold protein, cheX (yellow) for a dimer-form protein phosphatase, cheY (green) for a response regulator, and cheA/Y (a gradient from red to green) for a CheA-CheY fusion protein, as well as mcp (grey) coding for a methyl-accepting chemotaxis protein and other genes (white). Locus tags and types of chemotaxis clusters are listed next to the diagrams. The types of chemotaxis clusters are identified by comparing with the well-known 6 types of chemotaxis clusters conserved in the genomes of Geobacter sulfurreducens, Geobacter metallireducens and Geobacter uraniireducens. E. coli-like type 2 contains the non-chemotaxis genes and multiple mcp genes in the cluster. Frz-like type contains the cheA/Y fusion genes in the cluster. Dif-like type contains the genes of 44H-mcp, cheA, cheC, cheD, cheW and cheY in the cluster. Deltaproteobacteria-specific β group clusters contain the genes of cheA, cheB, cheR and cheW, but no mcp genes. Red-colored background of the gene clusters indicates the specific clusters to the flagellum-possessing strains AOP6 and 2873T, while grey-colored background indicates the common clusters to the 5 strains