Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
J Biol Chem. 2012 Aug 17;287(34):29035-44. doi: 10.1074/jbc.M112.361261. Epub 2012 Jul 3.
Phosphoglycerate kinase (PGK), present on the surface of group B streptococcus (GBS), has previously been demonstrated to bind the host proteins actin and plasminogen. The actin and plasminogen binding sites of GBS-PGK were identified using truncated GBS-PGK molecules, followed by peptide mapping. These experiments identified two actin and plasminogen binding sites located between amino acids 126-134 and 204-208 of the 398-amino acid-long GBS-PGK molecule. Substitution of the lysine residues within these regions with alanine resulted in significantly reduced binding to both actin and plasminogen. In addition, conversion of the glutamic acid residue at amino acid 133 to proline, the amino acid found at this position for the PGK protein of Streptococcus pneumoniae, also resulted in significantly reduced binding to actin and plasminogen. These results demonstrate that the lysine residues at amino acid positions 126, 127, 130, 204, and 208 along with the glutamic acid residue at amino acid position 133 are necessary for actin and plasminogen binding by GBS-PGK.
磷酸甘油酸激酶（PGK）存在于 B 族链球菌（GBS）表面，先前已被证明可与宿主蛋白肌动蛋白和纤溶酶原结合。使用截断的 GBS-PGK 分子，然后进行肽图分析，确定了 GBS-PGK 的肌动蛋白和纤溶酶原结合位点。这些实验确定了位于 GBS-PGK 398 个氨基酸长分子的 126-134 位氨基酸和 204-208 位氨基酸之间的两个肌动蛋白和纤溶酶原结合位点。在这些区域内将赖氨酸残基替换为丙氨酸会导致与肌动蛋白和纤溶酶原的结合显著减少。此外，将氨基酸 133 处的谷氨酸残基转换为丙氨酸，该位置在肺炎链球菌的 PGK 蛋白中发现，也会导致与肌动蛋白和纤溶酶原的结合显著减少。这些结果表明，氨基酸位置 126、127、130、204 和 208 处的赖氨酸残基以及氨基酸位置 133 处的谷氨酸残基是 GBS-PGK 与肌动蛋白和纤溶酶原结合所必需的。
