A walk into the LuxR regulators of Actinobacteria: phylogenomic distribution and functional diversity

PLoS One. 2012;7(10):e46758. doi: 10.1371/journal.pone.0046758. Epub 2012 Oct 8.

Abstract

LuxR regulators are a widely studied group of bacterial helix-turn-helix (HTH) transcription factors involved in the regulation of many genes coding for important traits at an ecological and medical level. This regulatory family is particularly known by their involvement in quorum-sensing (QS) mechanisms, i.e., in the bacterial ability to communicate through the synthesis and binding of molecular signals. However, these studies have been mainly focused on gram-negative organisms, and the presence of LuxR regulators in the gram-positive Actinobacteria phylum is still poorly explored. In this manuscript, the presence of LuxR regulators among Actinobacteria was assayed using a domain-based strategy. A total of 991 proteins having one LuxR domain were identified in 53 genome-sequenced actinobacterial species, of which 59% had an additional domain. In most cases (53%) this domain was REC (receiver domain), suggesting that LuxR regulators in Actinobacteria may either function as single transcription factors or as part of two-component systems. The frequency, distribution and evolutionary stability of each of these sub-families of regulators was analyzed and contextualized regarding the ecological niche occupied by each organism. The results show that the presence of extra-domains in the LuxR-regulators was likely driven by a general need to physically uncouple the signal sensing from the signal transduction. Moreover, the total frequency of LuxR regulators was shown to be dependent on genetic, metabolic and ecological variables. Finally, the functional annotation of the LuxR regulators revealed that the bacterial ecological niche has biased the specialization of these proteins. In the case of pathogens, our results suggest that LuxR regulators can be involved in virulence and are therefore promising targets for future studies in the health-related biotechnology field.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinobacteria / drug effects*
  • Actinobacteria / genetics
  • Actinobacteria / metabolism*
  • Gene Expression Regulation, Bacterial
  • Phylogeny
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*

Substances

  • Repressor Proteins
  • Trans-Activators
  • LuxR autoinducer binding proteins

Grants and funding

This work was funded by the European Regional Development Fund through COMPETE program and FCT - Fundação para a Ciência e Tecnologia, with the project FCOMP-01-0124-FEDER-022718 (ref FCT Pest-C/SAU/LA0002/2011). MVM was supported by “Programa Ciência 2007” sponsored by POPH QREN Tipologia 4.2 Promoção do Emprego Cientifico program and co-financed by the European Social Fund and Portuguese national funds from the MCTES. CLS was supported by the FCT fellowship SFRH/BPD/62978/2009. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.