Heme-dependent autophosphorylation of a heme sensor kinase, ChrS, from Corynebacterium diphtheriae reconstituted in proteoliposomes

Abstract 

Corynebacterium diphteriae employs the response regulator, ChrA, and the sensor kinase, ChrS, of a two-component signal transduction system to utilize host heme iron. Although ChrS is predicted to encode a heme sensor, the sensing mechanism remains to be characterized. In this report, ChrS expressed in Eshcherichia coli membranes was solubilized and purified using decylmaltoside. ChrS protein incorporated into proteoliposomes catalyzed heme-dependent autophosphorylation by ATP. Other metalloporphyrins and iron did not stimulate kinase activity. The UV–Vis spectrum of hemin in the ChrS–proteoliposomes indicated that heme directly interacts with ChrS. This is the first functional reconstitution of a bacterial heme-sensing protein.

Abbreviations: Hb, hemoglobin, HK, histidine kinase, RR, response regulator, OG, n-octyl-β-d-glucoside, DM, n-decyl-β-d-maltoside, DMSO, dimethyl sulfoxide, PP, protoporphyrin IX, PAGE, polyacrylamide gel electrophoresis, TM, transmembrane region

Keywords: Heme sensor, Two-component system, Histidine kinase, Autophosphorylation, Liposome