Katerov V, Lindgren P E, Totolian A A, Schalén C
Department of Infectious Diseases and Medical Microbiology, Lund University, Sölvegatan 23, S-22362 Lund, Sweden.
Curr Microbiol. 2000 Mar;40(3):149-56. doi: 10.1007/s002849910031.
The serum opacity factor (SOF) of Streptococcus pyogenes is a type-specific lipoproteinase of unknown biological significance. We have sequenced the sof gene and characterized the corresponding SOF protein from a strain of type M63. It was found that sof63 is related to sof22 and that, similar to SOF22 [25], SOF63 binds fibronectin. Moreover, we demonstrate opacity factor activity in a Streptococcus dysgalactiae fibronectin-binding protein FnBA that is structurally related to the SOF proteins of S. pyogenes. Sequence analysis of these three SOF proteins showed a unique periodical pattern of conserved and variable regions. The enzymatically active part of SOF63 was localized to the fragment corresponding to the entire set of conserved and variable sequences, while for fibronectin-binding a single repeat in the C terminal part of the protein was sufficient. The results show that streptococcal SOF proteins form a novel family of bifunctional proteins with lipoproteinase and fibronectin-binding activities.
化脓性链球菌的血清混浊因子（SOF）是一种类型特异性脂蛋白酶，其生物学意义尚不清楚。我们对sof基因进行了测序，并对一株M63型菌株的相应SOF蛋白进行了表征。发现sof63与sof22相关，并且与SOF22 [25]相似，SOF63结合纤连蛋白。此外，我们在与化脓性链球菌的SOF蛋白结构相关的嗜热栖热放线菌纤连蛋白结合蛋白FnBA中证明了混浊因子活性。对这三种SOF蛋白的序列分析显示了保守和可变区域的独特周期性模式。SOF63的酶活性部分定位于与整个保守和可变序列相对应的片段，而对于纤连蛋白结合，蛋白质C末端部分的单个重复就足够了。结果表明，链球菌SOF蛋白形成了一个具有脂蛋白酶和纤连蛋白结合活性的新型双功能蛋白家族。
