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首页> 外文期刊>Microbial Pathogenesis >Roles of conserved nucleotide-binding domains in accessory proteins, HypB and UreG, in the maturation of nickel-enzymes required for efficient Helicobacter pylori colonization
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Roles of conserved nucleotide-binding domains in accessory proteins, HypB and UreG, in the maturation of nickel-enzymes required for efficient Helicobacter pylori colonization

机译：辅助蛋白HypB和UreG中保守的核苷酸结合结构域在有效幽门螺杆菌定植所需的镍酶成熟中的作用

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摘要

Helicobacter pylori synthesizes two nickel-containing enzymes (urease and hydrogenase), both of which are important pathogenesis factors. Among the many accessory proteins needed for maturation of these Ni-enzymes, are two proteins, HypB and UreG, each of which contain a conserved nucleotide-binding domain (GSGKT). To address the role of this domain in the maturation process, site-directed mutations were introduced in both hypB and ureG. The hypB site-directed mutant strain (Lys59 to Ala59) lacked hydrogenase activity and had less than 1% of the parental urease activity. Hydrogenase activity was partially, and urease activity was fully restored in the hypB mutant strain when grown on nickel supplemented media. The hydrogenase activity of the ureG site-directed mutant strain (Lys14 to Ala14) was comparable to that of the parental strain. However, the ureG mutant strain lacked urease activity, and this deficiency could not be suppressed even when the strain was grown on nickel supplemented media. The expression of immunologically detectable HypB and UreG in the mutants was similar to the parental strain. Expression of the UreA and UreB subunits of urease in both the mutants was also normal. Purified UreG parental and mutant (Lys14 to Ala14) proteins had molecular masses of 27 kDa, but possessed negligible GTP hydrolyzing activity.
机译：幽门螺杆菌合成两种含镍的酶（脲酶和氢化酶），这两种酶都是重要的发病因素。这些Ni酶成熟所需的许多辅助蛋白质中，有HypB和UreG这两种蛋白质，每个蛋白质都包含一个保守的核苷酸结合域（GSGKT）。为了解决该结构域在成熟过程中的作用，在hypB和ureG中都引入了定点突变。 hypB定点突变菌株（Lys59至Ala59）缺乏氢化酶活性，并且其亲本脲酶活性不到1％。当在补充镍的培养基上生长时，hypB突变菌株中的氢化酶活性部分得到恢复，脲酶活性得以完全恢复。 ureG定点突变菌株（Lys14至Ala14）的氢化酶活性与亲本菌株相当。但是，ureG突变菌株缺乏脲酶活性，即使该菌株在补充镍的培养基上生长，也无法抑制这种缺陷。突变体中可免疫检测的HypB和UreG的表达与亲本菌株相似。在两个突变体中，脲酶的UreA和UreB亚基的表达也是正常的。纯化的UreG亲本和突变蛋白（Lys14至Ala14）的分子质量为27 kDa，但GTP水解活性可忽略不计。

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