histidine residue 94 is involved in ph sensing by histidine kinase arss of helicobacter pylori组氨酸残基94年由组氨酸激酶参与ph值传感ars幽门螺杆菌.pdfVIP

Histidine Residue 94 Is Involved in pH Sensing by Histidine Kinase ArsS of Helicobacter pylori ¨ ¤ ¨ Stefanie Muller , Monika Gotz, Dagmar Beier* ¨ ¨ ¨ ¨ ¨ Theodor-Boveri-Institut fur Biowissenschaften, Lehrstuhl fur Mikrobiologie, Universitat Wurzburg, Am Hubland, Wurzburg, Germany Abstract Background: The ArsRS two-component system is the master regulator of acid adaptation in the human gastric pathogen Helicobacter pylori. Low pH is supposed to trigger the autophosphorylation of the histidine kinase ArsS and the subsequent transfer of the phosphoryl group to its cognate response regulator ArsR which then acts as an activator or repressor of pH- responsive genes. Orthologs of the ArsRS two-component system are also present in H. pylori’s close relatives H. hepaticus, Campylobacter jejuni and Wolinella succinogenes which are non-gastric colonizers. Methodology/Principal Findings: In order to investigate the mechanism of acid perception by ArsS, derivatives of H. pylori 26695 expressing ArsS proteins with substitutions of the histidine residues present in its periplasmic input domain were constructed. Analysis of pH-responsive transcription of selected ArsRS target genes in these mutants revealed that H94 is relevant for pH sensing, however, our data indicate that protonatable amino acids other than histidine contribute substantially to acid perception by ArsS. By the construction and analysis of H. pylori mutants carrying arsS allels from the related e-proteobacteria we demonstrate that WS1818 of W. succinogenes efficiently responds to acidic pH. Conclusions/Significance: We show that H94 in the input domain of ArsS is crucial for acid perception in H. pylori 26695. In ad