Transcriptional analysis of the gum gene cluster from Xanthomonas oryzae pathovar oryzae

Genome sequence analysis of Xanthomonas oryzae pv. oryzae KACC10331 provides insight into the X. oryzae gum gene cluster that is composed of 14 open-reading frames (ORFs), designated gumB, -C, -D, -E, -F, -G, -H, -I, -J, -K, -L, -M, XOO3167, and -N. We analyzed the transcriptional linkage of the X. oryzae gum gene cluster by using RT-PCR. Analyses of the gum gene cluster by RT-PCR with the wild-type and mutant strains, which carried a deletion of the promoter-like region upstream of gumB or an insertion of the rrnB transcriptional terminator into the gumF gene, revealed that the ORFs of this gene cluster were transcribed as polycistronic mRNA, from gumB to gumN, and the secondary promoter was located upstream of gumG. Taken together, these results suggest that the genes of this cluster constitute an operon expressed from overlapping transcripts.