In Salmonella typhimurium, nearly 50 genes are involved in flagellar formation and function and constitute at least 13 different operons. In this study, we examined the transcriptional interaction among the flagellar operons by combined use of Mu d1(Apr Lac) cts62 and Tn10 insertion mutants in the flagellar genes. The results showed that the flagellar operons can be divided into three classes: ...

Grouping genes as operons is an important genomic feature of prokaryotic organisms. The comprehensive understanding of the operon organizations would be helpful to decipher transcriptional mechanisms, cellular pathways, and the evolutionary landscape of prokaryotic genomes. Although thousands of prokaryotes have been sequenced, genome-wide investigation of the evolutionary dynamics (division an...

Genome-wide measurements of transcriptional activity in bacteria indicate that the transcription of successive genes is strongly correlated beyond the scale of operons. Here, we analyze hundreds of bacterial genomes to identify supra-operonic segments of genes that are proximal in a large number of genomes. We show that these synteny segments correspond to genomic units of strong transcriptiona...

Sir, Resistance to vancomycin in Enterococcus faecium and Enterococcus faecalis is due to acquired operon structures of two types, namely the D-alanyl-D-lactate and D-alanyl-D-serine operons named for the specific ligase they harbour. The former group consists of the vanA, vanB, vanD and vanM operons and the latter group consists of the vanE, vanG, vanL and vanN operons. – 5 The D-Ala-D-Lac ope...

Rhodococcus sp. strain DK17 is able to grow on o-xylene, benzene, toluene, and ethylbenzene. DK17 harbors at least two megaplasmids, and the genes encoding the initial steps in alkylbenzene metabolism are present on the 330-kb pDK2. The genes encoding alkylbenzene degradation were cloned in a cosmid clone and sequenced completely to reveal 35 open reading frames (ORFs). Among the ORFs, we ident...

The occurrence of fim, pap, sfa, and afa genes was evaluated in 200 Escherichia coli strains isolated from chickens diagnosed with omphalitis, salpingitis, swollen head syndrome, or chronic respiratory disease. Analysis of the strains by colony hybridization tests demonstrated that 96% of the isolates were fim, 16% were pap, and 6% were sfa. None of the isolates was afa. The fim gene occurred i...

Previously, we reported finding duplicated fixNOQP operons in Rhizobium etli CFN42. One of these duplicated operons is located in the symbiotic plasmid (fixNOQPd), while the other is located in a cryptic plasmid (fixNOQPf). Although a novel FixL-FixKf regulatory cascade participates in microaerobic expression of both fixNOQP duplicated operons, we found that a mutation in fixL eliminates fixNOQ...

A comparative study was completed to determine the influence of various environmental stimuli on the transcription of three different fimbrial operons in Escherichia coli and to determine the role of the histone-like protein H-NS in this environmental regulation. The fimbrial operons studied included the pap operon, which encodes pyelonephritis-associated pili (P pili), the daa operon, which en...