Genetic environment of the chromosomal poxtA gene. Genes are indicated as arrows, with the arrowhead showing the direction of transcription. The genes with different functions are displayed in different colours. The Δ symbol indicates a truncated gene. The direct target site duplications are boxed. The position of the fexB-carrying TU5 is indicated. Grey shading indicates shared regions with >99% nucleotide sequence identity. This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.