Philominathan Sagaya Theresa Leena, Koide Takaki, Hamada Kentaro, Yasui Hiroyuki, Seifert Soenke, Matsushita Osamu, Sakon Joshua
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA.
J Biol Chem. 2009 Apr 17;284(16):10868-76. doi: 10.1074/jbc.M807684200. Epub 2009 Feb 10.
Histotoxic clostridia produce collagenases responsible for extensive tissue destruction in gas gangrene. The C-terminal collagen-binding domain (CBD) of these enzymes is the minimal segment required to bind to collagen fibril. Collagen binding efficiency of CBD is more pronounced in the presence of Ca(2+). We have shown that CBD can be functional to anchor growth factors in local tissue. A (1)H-(15)N HSQC NMR titration study with three different tropocollagen analogues ((POG)(10))(3), ((GPOG)(7)PRG)(3), and (GPRG(POG)(7)C-carbamidomethyl)(3), mapped a saddle-like binding cleft on CBD. NMR titrations with three nitroxide spin-labeled analogues of collagenous peptide, (PROXYL-G(POG)(7)PRG)(3), (PROXYL-G(POG)(7))(3), and (GPRG(POG)(7)C-PROXYL)(3) (where PROXYL represents 2,2,5,5-tetramethyl-l-pyrrolidinyloxy), unambiguously demonstrated unidirectional binding of CBD to the tropocollagen analogues. Small angle x-ray scattering data revealed that CBD binds closer to a terminus for each of the five different tropocollagen analogues, which in conjunction with NMR titration studies, implies a binding mode where CBD binds to the C terminus of the triple helix.
组织毒性梭状芽孢杆菌产生的胶原酶是气性坏疽中导致广泛组织破坏的原因。这些酶的C末端胶原结合结构域（CBD）是与胶原纤维结合所需的最小片段。在Ca(2+)存在的情况下，CBD的胶原结合效率更为显著。我们已经表明，CBD可在局部组织中发挥锚定生长因子的功能。对三种不同的原胶原类似物（(POG)(10)）(3)、((GPOG)(7)PRG)(3)和(GPRG(POG)(7)C-氨基甲酰甲基)(3)进行的(1)H-(15)N HSQC NMR滴定研究，在CBD上绘制出一个鞍状结合裂隙。用三种胶原肽的氮氧自旋标记类似物（(PROXYL-G(POG)(7)PRG)(3)、(PROXYL-G(POG)(7))(3)和(GPRG(POG)(7)C-PROXYL)(3)，其中PROXYL代表2,2,5,5-四甲基-1-吡咯烷基氧基）进行的NMR滴定，明确证明了CBD与原胶原类似物的单向结合。小角X射线散射数据显示，对于五种不同的原胶原类似物中的每一种，CBD都更靠近一个末端结合，这与NMR滴定研究相结合，意味着一种结合模式，即CBD与三螺旋的C末端结合。
