preview

The Two Component Stressors

Good Essays

Introduction

Bacteria are prone to various stressors so they need to sense and respond to these fluctuating conditions in order to survive. Two-component plays an important role in the bacterial kingdom to sense and adapt themselves to these varieties of stressors, for example oxidative stress, protein misfolding, nutrient starvation and many more. It is first described by Ninfa and Magasanik (1986) in the study of nitrogen starvation in Escherichia coli. Two-component system consists of a sensor histidine kinase and its cognate response regulator (Koretke,K.K. 2000). Sensor histidine kinase is bifunctional which means it can function as both kinase and phosphatase. It autophosphorylates itself upon sensing a signal, whereby the phosphoryl group from ATP molecule is transferred to a specific histine residue on the histidine kinase. It then acts as phosphodonor substrate for its cognate response regulator. The cognate response regulators is acting as phosphatase to the histidine kinase as it catalyses the transfer of the phosphoryl group from histidine kinase to its conserved aspartic acid residue. Once phosphorylated, response regulator undergoes conformational change which activates the output domain leading to either stimulation or repression of the targeted genes. As mentioned earlier on, histidine kinase protein also acts as phosphatase for its cognate response regulator if it is not stimulated to autophosphorylate.

This system has vast variations and the common

Get Access