Iwasaki M, Igarashi H, Hinuma Y, Yutsudo T
Shionogi Institute for Medical Science, Osaka, Japan.
FEBS Lett. 1993 Sep 27;331(1-2):187-92. doi: 10.1016/0014-5793(93)80323-m.
A new type of mitogenic factor, termed MF, has been found in the culture supernatant of Streptococcus pyogenes and its N-terminal amino acid sequence has been determined. On the basis of this sequence, an S. pyogenes gene encoding MF was cloned and its nucleotide sequence was determined. The MF gene includes a long, open reading frame with 813 nucleotides capable of encoding the MF precursor protein with 271 amino acids. Removal of the putative 43 residues as a signal peptide results in the mature MF protein with 228 amino acids. The molecular mass of the mature MF is calculated as 25,363 which is consistent with the previously determined value of 25,370 for MF secreted from S. pyogenes. Neither nucleotide nor amino acid sequence homology was found between the mature MF and other streptococcal pyrogenic exotoxins, such as SPE A, SPE B and SPE C. The mature MF was recombinantly overexpressed as a fusion protein with glutathione S-transferase in Escherichia coli. The recombinant protein showed mitogenic activity in rabbit peripheral blood lymphocytes and immunoreactivity with the rabbit antiserum raised against the secreted MF from S. pyogenes. These data indicate that a unique gene encoding MF was cloned from S. pyogenes.
在化脓性链球菌的培养上清液中发现了一种新型促有丝分裂因子，称为MF，并确定了其N端氨基酸序列。基于该序列，克隆了化脓性链球菌中编码MF的基因并确定了其核苷酸序列。MF基因包含一个长813个核苷酸的开放阅读框，能够编码含有271个氨基酸的MF前体蛋白。去除作为信号肽的假定43个残基后，产生了含有228个氨基酸的成熟MF蛋白。成熟MF的分子量计算为25363，这与先前测定的化脓性链球菌分泌的MF的25370值一致。在成熟MF与其他链球菌热原性外毒素（如SPE A、SPE B和SPE C）之间未发现核苷酸或氨基酸序列同源性。成熟MF在大肠杆菌中作为与谷胱甘肽S-转移酶的融合蛋白进行重组过表达。重组蛋白在兔外周血淋巴细胞中显示出促有丝分裂活性，并与针对化脓性链球菌分泌的MF产生的兔抗血清具有免疫反应性。这些数据表明从化脓性链球菌中克隆了一个编码MF的独特基因。
