5'-核苷酸酶
细胞质
水解酶
细胞内
周质间隙
核苷酸酶
生物化学
生物
核糖核酸酶
酶
细胞生物学
化学
大肠杆菌
核糖核酸
基因
作者
David J. Innes,Ifor R. Beacham,Dennis M. Burns
标识
DOI:10.1002/1521-4028(200112)41:6<329::aid-jobm329>3.0.co;2-4
摘要
E. coli UshA, a bifunctional enzyme with UDP-sugar hydrolase and 5′-nucleotidase activities, is secreted to the periplasm but has a specific protein inhibitor located in the cytoplasm. It has been previously suggested that some 5′-nucleotidase, or a folded domain of this enzyme, may be active in the cytoplasm prior to export. If true, the intracellular inhibitor may have a role in protecting the cell from the likely deleterious effects of any intracellular UshA activity. Using deletion mutagenesis to remove the UshA signal peptide, we have shown that the resulting UshA derivative is an active cytoplasmic 5′-nucleotidase, and causes conditional lethality. Our results support the hypothesis that the physiological role of the UshA inhibitor is to protect the intracellular nucleotide pool from any cytoplasmic 5′-nucleotidase activity.
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