Comparative analysis of wolbachia genomes reveals streamlining and divergence of minimalist two-component systems

G3 (Bethesda). 2015 Mar 24;5(5):983-96. doi: 10.1534/g3.115.017137.


Two-component regulatory systems are commonly used by bacteria to coordinate intracellular responses with environmental cues. These systems are composed of functional protein pairs consisting of a sensor histidine kinase and cognate response regulator. In contrast to the well-studied Caulobacter crescentus system, which carries dozens of these pairs, the streamlined bacterial endosymbiont Wolbachia pipientis encodes only two pairs: CckA/CtrA and PleC/PleD. Here, we used bioinformatic tools to compare characterized two-component system relays from C. crescentus, the related Anaplasmataceae species Anaplasma phagocytophilum and Ehrlichia chaffeensis, and 12 sequenced Wolbachia strains. We found the core protein pairs and a subset of interacting partners to be highly conserved within Wolbachia and these other Anaplasmataceae. Genes involved in two-component signaling were positioned differently within the various Wolbachia genomes, whereas the local context of each gene was conserved. Unlike Anaplasma and Ehrlichia, Wolbachia two-component genes were more consistently found clustered with metabolic genes. The domain architecture and key functional residues standard for two-component system proteins were well-conserved in Wolbachia, although residues that specify cognate pairing diverged substantially from other Anaplasmataceae. These findings indicate that Wolbachia two-component signaling pairs share considerable functional overlap with other α-proteobacterial systems, whereas their divergence suggests the potential for regulatory differences and cross-talk.

Keywords: Wolbachia; endosymbiont; genome organization; two-component signaling; α-proteobacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acids
  • Computational Biology / methods
  • Gene Order
  • Genes, Bacterial
  • Genetic Loci
  • Genome, Bacterial*
  • Genomics* / methods
  • Molecular Sequence Data
  • Open Reading Frames
  • Operon
  • Protein Interaction Domains and Motifs
  • Sequence Alignment
  • Signal Transduction*
  • Wolbachia / genetics*
  • Wolbachia / metabolism*


  • Amino Acids