Fused and Overlapping rpoB and rpoC Genes in Helicobacters, Campylobacters, and Related Bacteria

Abstract

The genes coding for the β (rpoB) and β′ (rpoC) subunits of RNA polymerase are fused in the gastric pathogen Helicobacter pylori but separate in other taxonomic groups. To better understand how the unique fused structure evolved, we determined DNA sequences at and around therpoB-rpoC junction in 10 gastric and nongastric species ofHelicobacter and in members of the related generaWolinella, Arcobacter,Sulfurospirillum, and Campylobacter. We found the fusion to be specific to Helicobacter andWolinella genera; rpoB and rpoCoverlap in the other genera. The fusion may have arisen by a frameshift mutation at the site of rpoB and rpoC overlap. Loss of good Shine-Dalgarno sequences might then have fixed the fusion in the Helicobacteraceae, even if fusion itself did not confer a selective advantage.

Molecular signatures (unique proteins and conserved indels) that are specific for the epsilon proteobacteria (Campylobacterales)

“…In addition to these conserved indels, Zakaharova et al [ 62 ] have identified a rare genetic event that causes fusion of two different genes within certain groups of ε-proteobacteria. The two largest and highly conserved subunits of RNA polymerase (RpoB and RpoC, each approximately 1400 aa) are encoded by two distinct genes in various bacteria [ 62 ]. However, a rare genetic event has led to the fusion of these genes in Helicobacter and Wolinella species, such that RpoB and RpoC are now made as a single large polypeptide (≈ 2900 aa) (Fig.…”

Nucleotide sequence of thegyrAgene ofArcobacterspecies and characterization of human ciprofloxacin-resistant clinical isolates

“…In conclusion, the gyrA gene appears sufficiently conserved over evolution to be used as a taxonomic tool, as well as other genes, e.g. the gyrB gene (Laatu et al , 2005) and the rpoB ‐ rpoC gene (Zakharova et al , 1999; Morita et al , 2004). Sequencing of the gyrA gene in other species in the Epsilonproteobacteriaceae group will allow the creation of a complete taxonomic tree, which will be helpful in the future.…”

“…Consequently, to compare Arcobacter sequences with those of other Epsilonproteobacteria , it would be ideal to have an alternative support to 16S rRNA gene. Therefore, other target genes have been considered already: 23S rRNA gene (Miyajima et al , 2002; Dewhirst et al , 2005), rpoB (Zakharova et al , 1999), and gyrB (Laatu et al , 2005). Our goal was to determine the entire sequence of the gyrA gene which has also been found of taxonomic interest in other bacteria (Huang, 1996; Sander et al , 1998) in order to assess its taxonomic value in Arcobacters.…”

A Decrease in Transcription Capacity Limits Growth Rate upon Translation Inhibition

“…The extreme length of the β and β′ subunits of RNAP is conserved throughout bacteria ( 47 ). In the case of Helicobacteraceae and Wolbachia , the two genes are even fused together ( 47 , 48 ). The gene length of β and β′ subunits can vary in different strains since they are composed of independent structural modules separated by spacers of differing length ( 47 ).…”