D.radiodurans kat A和kat B基因的结构分析与功能鉴定

以简并引物PCR获得的Cat酶基因片段探针，结合生物信息学方法，探明了耐辐射奇球菌（D.radiodu-rans)基因组中存在两个编码过氧化氢酶（Catalase,Cat)的基因：katA和B.katA和katB基因长2277bp和1611bp，各编码758和536个氨基酸，用pKK223-3表达载体连接katB基因，转入Cat酶缺陷型大肠杆菌（E. coliUM2)进行表达.katB基因表达产物具有Cat酶活性，电泳迁移位置与D.radiodurans CatB酶位置相符，并可重建E.coliUM2对低浓度H2O2损伤的耐受力。

STRUCTURE ANALYSIS AND FUNCTION CHARACTERIZATION OF kat A AND kat B GENE FROM DEINOCOCCUS RADIODURANS

By using a 672 bp length catalase gene fragment as probe which had been amplified from D. radiodurans genome DNA by degenerate primers PCR reaction and bioimformatical analysis, two complete coding sequences of the catalase were determined from the database of D. radiodurans genome, which were then designated as kat A and kat B gene. The kat A and kat B gene were 2 277 bp and 1 611 bp long, encoding 758 and 536 amino acids, respectively. The kat B gene was cloned into pKK223-3 expressing vector and transformed into the E. coli UM2, a catalase-deficient mutant. Staining of non-denatured PAGE for catalase activity demonstrated that kat B gene inserted into pKK223-3 encoded a catalase that co-migrated with the CatB found in D. radiodurans cell lysates. It was also observed that expression of kat B gene in E. coli UM2 could restore the resistance to H 2O 2 at low concentration. Fig 4, Ref 10