1996-2019. All Rights Reserved. Online Journal of Bioinformatics . You may not store these pages in any form except for your own personal use. All other usage or distribute on is illegal under international copyright treaties. Permission to use any of these pages in any other way besides the  before mentioned must be gained in writing from the publisher. This article is exclusively copyrighted in its entirety to OJB publications. This article may be copied once but may not be, reproduced or  re-transmitted without the express permission of the editors. This journal satisfies the refereeing requirements (DEST) for the Higher Education Research Data Collection (Australia). Linking:To link to this page or any pages linking to this page you must link directly to this page only here rather than put up your own page.


Online Journal of Bioinformatics 

Volume 12(1):167-174, 2011

Detection and classification of two-component osmoregulatory systems


Srividhya K V and S Krishnaswamy.


Centre of Excellence in Bioinformatics, School of Biotechnology, Madurai Kamaraj University, Madurai-625021, Tamilnadu, India




Srividhya KV, Krishnaswamy S., Detection and classification of two-component osmoregulatory systems, Onl J Bioinform., 12(1):167-174, 2011. Two-component signal transduction (TCST) systems are the principal means for coordinating responses to environmental changes in bacteria as well as in some plants, fungi, protozoa and archaea. These systems typically consist of a receptor histidine kinase, which reacts to an extracellular signal by phosphorylating a cytoplasmic response regulator, thereby causing a change in cellular behavior. Osmoregulation is one of the well studied two-component system operative in bacteria and plays a crucial role in regulating the cellular response to varied solute environments. In E coli EnvZ, a transmembrane protein acts as sensor and its cognate response regulator OmpR coordinates the osmoregulatory switch by controlling the expression of porins, OmpC and OmpF. In this report, genome-wide identification of osmoregulatory two-component protein orthologs has been carried out. 29 genomes are associated with EnvZ-OmpR system, which clustered into 6 subgroups based on genus with both EnvZ and OmpR from all sources clustering together. 17 E coli encoded two-component systems are homologous to EnvZ-OmpR. With EnvZ and OmpR all domain loci are conserved. The sensor and regulator partners show same clustering trends. Hidden Markov models (HMMs) built for EnvZ sensor kinase and OmpR response regulators families were used to search for homologs in other species. 39 two component systems were identified using PSI BLAST and HMM based approach. All tend to be conserved only in the domain locus. Most of them are systems associated with stress mediated responses. Most of sensors and their regulators fetched from different search methods using EnvZ -OmpR systems as template are also seen to be co-evolved. In conclusion, analysis revealed the homology of osmoregulatory family with most of the stress related or adaptive response related two-component systems.


Keywords: Osmoregulation, EnvZ, OmpR, Porins, profile searches, two-component system