金黄色葡萄球菌A蛋白基因的克隆及序列分析

 我们构建了金黄色葡萄球菌Cowan1株(CMCC26111)的染色体文库,转化大肠杆菌后筛选出一株protein A的阳性克隆。SDS-PAGE及Western-blot结果显示该克隆株表达的重组protein A的分子量为30 000,较天然protein A的小。该克隆中的protein A基因片段的序列分析表明,它含有天然protein A基因的启动子、信号肽以及至少四个与IgGFc段结合的结构域,而不含天然protein A的胞壁结合区,并发现其中有24个碱基对与Uhlen报告的protein A基因不同,由此导致三个编码的氨基酸发生变化,但这些差异并不影响该重组protein A与IgG Fc段的特异结合。

Cloning and Sequencing of Protein A from Staphylococcus Aureus Cowan 1 (CMCC26111)

The gene fragment encoding protein A from staphyloccoccus aureus Cowan 1 (CMCC26111) was isolated by recombinant DNA techniques, and a subclone containing a 1.2kb insert gave functional product in Escherichia coli.Nucleotide sequence analysis of the protein A gene fragment (1.2kb) showed that it contained the promoter region, signal sequence and five IgG Fc part binding domains, but the region X which existed in native protein A gene was deleted.Comparing sequences of protein A gene fragment from Cowan 1 strain with that from 8325-4 strain, 24 nucleotides and 3 amino acids variations were found.The differences locate at upstream promoter region or structure gene.The promoter region and signal sequence were identical in both sequences.