Blum Faith C, Hu Heidi Q, Servetas Stephanie L, Benoit Stéphane L, Maier Robert J, Maroney Michael J, Merrell D Scott
Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States of America.
Department of Chemistry and Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, United States of America.
PLoS One. 2017 Aug 15;12(8):e0183260. doi: 10.1371/journal.pone.0183260. eCollection 2017.
The nickel-containing enzymes of Helicobacter pylori, urease and hydrogenase, are essential for efficient colonization in the human stomach. The insertion of nickel into urease and hydrogenase is mediated by the accessory protein HypA. HypA contains an N-terminal nickel-binding site and a dynamic structural zinc-binding site. The coordination of nickel and zinc within HypA is known to be critical for urease maturation and activity. Herein, we test the hydrogenase activity of a panel of H. pylori mutant strains containing point mutations within the nickel- and zinc-binding sites. We found that the residues that are important for hydrogenase activity are those that were similarly vital for urease activity. Thus, the zinc and metal coordination sites of HypA play similar roles in urease and hydrogenase maturation. In other pathogenic bacteria, deletion of hydrogenase leads to a loss in acid resistance. Thus, the acid resistance of two strains of H. pylori containing a hydrogenase deletion was also tested. These mutant strains demonstrated wild-type levels of acid resistance, suggesting that in H. pylori, hydrogenase does not play a role in acid resistance.
幽门螺杆菌的含镍酶——脲酶和氢化酶，对于在人类胃部有效定殖至关重要。镍插入脲酶和氢化酶的过程由辅助蛋白HypA介导。HypA含有一个N端镍结合位点和一个动态结构锌结合位点。已知HypA中镍和锌的配位对于脲酶的成熟和活性至关重要。在此，我们测试了一组在镍结合位点和锌结合位点含有点突变的幽门螺杆菌突变株的氢化酶活性。我们发现，对氢化酶活性重要的残基与对脲酶活性同样重要的残基相同。因此，HypA的锌和金属配位位点在脲酶和氢化酶成熟过程中发挥相似作用。在其他致病细菌中，氢化酶缺失会导致耐酸性丧失。因此，我们还测试了两株含有氢化酶缺失的幽门螺杆菌菌株的耐酸性。这些突变株表现出野生型水平的耐酸性，表明在幽门螺杆菌中，氢化酶在耐酸性方面不起作用。
