Department of Biochemistry and Molecular Biology, Tel-Aviv University, 69978 Tel-Aviv, Israel.
Mol Genet Genomics. 2011 May;285(5):403-13. doi: 10.1007/s00438-011-0614-3. Epub 2011 Mar 26.
The integrase encoded by the lambdoid phage HK022 (Int-HK022) resembles its coliphage λ counterpart (Int-λ) in the roles of the cognate DNA arm binding sites and in controlling the direction of the reaction. We show here that within mammalian cells, Int-HK022 does not exhibit such a control. Rather, Int-HK022 recombined between all ten possible pairwise att site combinations, including attB × attB that was more effective than the conventional integrative attP × attB reaction. We further show that Int-HK022 depends on the accessory integration host factor (IHF) protein considerably less than Int-λ and exhibits stronger binding affinity to the att core. These differences explain why wild-type Int-HK022 is active in mammalian cells whereas Int-λ is active there only as an IHF-independent mutant.
λ 样噬菌体 HK022 的整合酶（Int-HK022）与其对应的大肠杆菌噬菌体 λ 整合酶（Int-λ）在同源 DNA 臂结合位点的作用和控制反应方向上相似。我们在这里表明，在哺乳动物细胞内，Int-HK022 并不表现出这种控制。相反，Int-HK022 在所有十种可能的成对 att 位点组合之间发生重组，包括 attB×attB，其效率高于传统的整合 attP×attB 反应。我们进一步表明，Int-HK022 对辅助整合宿主因子（IHF）蛋白的依赖性远低于 Int-λ，并且对 att 核心的结合亲和力更强。这些差异解释了为什么野生型 Int-HK022 在哺乳动物细胞中是活跃的，而 Int-λ 只有作为 IHF 非依赖性突变体才在那里活跃。
