Sato Y, Okamoto K, Kagami A, Yamamoto Y, Igarashi T, Kizaki H
Department of Biochemistry and Oral Health Science Center, Tokyo Dental College, Chiba City, Japan.
J Dent Res. 2004 Jul;83(7):534-9. doi: 10.1177/154405910408300705.
A previously unidentified 120-kDa protein was detected in Streptococcus mutans strain Z1 and was involved in the cold-agglutination of the strain. We have identified the gene, designated cnm, as being involved in the agglutination of strain Z1 following random mutagenesis. The amino acid sequence of the deduced Cnm protein exhibited high similarity to those of collagen-binding adhesins from staphylococci and other organisms. To confirm whether the protein is involved in collagen-binding, we cloned a cnm gene fragment, overexpressed it in E.coli, and prepared crude extracts. The extracts containing recombinant protein exhibited binding to immobilized collagen and laminin but not to fibronectin. Compared with the parental strain Z1, the cold-agglutination-negative mutant 05A02 exhibited reduced binding to collagen and laminin but retained that to fibronectin. This gene was detected in some strains of S. mutans. Therefore, the cnm gene encoded a new strain-specific member of the collagen-binding adhesin family.
在变形链球菌Z1菌株中检测到一种先前未鉴定的120 kDa蛋白质，它参与了该菌株的冷凝集作用。我们通过随机诱变鉴定出一个名为cnm的基因，它与菌株Z1的凝集作用有关。推导的Cnm蛋白的氨基酸序列与葡萄球菌和其他生物体的胶原结合黏附素具有高度相似性。为了证实该蛋白是否参与胶原结合，我们克隆了一个cnm基因片段，在大肠杆菌中进行过量表达，并制备了粗提物。含有重组蛋白的提取物显示出与固定化胶原和层粘连蛋白的结合，但不与纤连蛋白结合。与亲本菌株Z1相比，冷凝集阴性突变体05A02与胶原和层粘连蛋白的结合减少，但与纤连蛋白的结合保留。在一些变形链球菌菌株中检测到了这个基因。因此，cnm基因编码了胶原结合黏附素家族的一个新的菌株特异性成员。
