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首页> 外文期刊>Journal of bacteriology >Inositol monophosphatase activity from the Escherichia coli suhB gene product.
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Inositol monophosphatase activity from the Escherichia coli suhB gene product.

机译：大肠杆菌suhB基因产物的肌醇单磷酸酶活性。

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The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (Km = 0.071 mM; Vmax = 12.3 mumol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5' proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.
机译：suhB基因位于大肠杆菌染色体上55分钟处，编码268个氨基酸的蛋白质。 suhB突变等位基因已被分离为蛋白质分泌突变（secY24），热休克反应突变（rpoH15）和DNA合成突变（dnaB121）的外源抑制因子（K. Shiba，K。Ito和T. Yura， J. Bacteriol。160：696-701，1984; R. Yano，H.Nagai，K.Shiba，and T.Yura，J.Bacteriol。172：2124-2130，1990; S.Chang，D.Ng，L Baird，和C.Georgopoulos，J.Biol.Chem.266：3654-3660，1991）。 suhB的这些突变等位基因引起冷敏感细胞的生长，表明suhB基因在低温下必不可少。然而，几乎没有工作来阐明suhB产物在正常细胞中的作用以及上述突变体中suhB突变的抑制机制。 suhB基因产物与哺乳动物肌醇单磷酸酶之间共有的序列相似性促使我们测试suhB基因产物的肌醇单磷酸酶活性。我们在这里报告，纯化的SuhB蛋白显示肌醇单磷酸酶活性。 SuhB肌醇单磷酸酶的动力学参数（Km = 0.071 mM; Vmax = 12.3μmol/ min / mg）与哺乳动物肌醇单磷酸酶的动力学参数相似。分别被分离为secY24和rpoH15的外源抑制剂的ssyA3和suhB2突变在suhB基因的5'近端区域具有DNA插入，​​并且突变细胞内SuhB蛋白的数量减少了。讨论了suhB在大肠杆菌中的可能作用。

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