Ye Z H, Lee C Y
Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City 66103.
J Bacteriol. 1989 Aug;171(8):4146-53. doi: 10.1128/jb.171.8.4146-4153.1989.
The nucleotide sequence of a staphylococcal bacteriophage L54a DNA fragment containing genes involved in site-specific recombination was determined. Mutations generated by in vitro mutagenesis were used to map and characterize the int and xis genes. The site-specific recombination functions are tightly clustered within a 1.75-kilobase stretch of DNA fragment with the gene order of attP-int-xis. The int and xis genes are transcribed divergently. The Int protein deduced from the nucleotide sequence has a molecular weight of 41,000. Int is a basic protein with 354 amino acids of which 72 are basic and 38 are acidic. The Xis protein consists of only 59 amino acids with a molecular weight of 7,180. Unlike the Xis proteins of the lambdoid bacteriophages which are all basic proteins, L54a Xis is an acidic protein containing 13 acidic and 8 basic amino acids. The Int protein is required in both integrative and excisive reactions, whereas Xis is only required in excisive reaction. A well-conserved 40-residue region, including three perfectly conserved residues found in 15 site-specific recombinases of the integrase family that have been characterized, was also found in the L54a Int protein.
测定了葡萄球菌噬菌体L54a DNA片段的核苷酸序列，该片段包含参与位点特异性重组的基因。通过体外诱变产生的突变用于定位和表征int和xis基因。位点特异性重组功能紧密聚集在一段1.75千碱基的DNA片段内，基因顺序为attP-int-xis。int和xis基因转录方向相反。从核苷酸序列推导的Int蛋白分子量为41,000。Int是一种碱性蛋白，有354个氨基酸，其中72个是碱性的，38个是酸性的。Xis蛋白仅由59个氨基酸组成，分子量为7,180。与所有碱性蛋白的λ样噬菌体的Xis蛋白不同，L54a Xis是一种酸性蛋白，含有13个酸性氨基酸和8个碱性氨基酸。Int蛋白在整合和切除反应中都需要，而Xis仅在切除反应中需要。在L54a Int蛋白中还发现了一个保守的40个残基区域，包括在已表征的整合酶家族的15种位点特异性重组酶中发现的三个完全保守的残基。
