Bann J G, Peyton D H, Bächinger H P
Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, 3108 SW Sam Jackson Park Road, Portland, OR, USA.
FEBS Lett. 2000 May 12;473(2):237-40. doi: 10.1016/s0014-5793(00)01493-9.
For most collagens, the melting temperature (T(m)) of the triple-helical structure of collagen correlates with the total content of proline (Pro) and 4-trans-hydroxyproline (Hyp) in the Xaa and Yaa positions of the -Gly-Xaa-Yaa- triplet repeat. The cuticle collagen of the deep-sea hydrothermal vent worm Riftia pachyptila, despite a very low content of Pro and Hyp, has a relatively high thermal stability. Rather than Hyp occupying the Yaa position, as is normally found in mammalian collagens, this position is occupied by threonine (Thr) which is O-glycosylated. We compare the triple-helix forming propensities in water of two model peptides, Ac-(Gly-Pro-Thr)(10)-NH(2) and Ac-(Gly-Pro-Thr(Galbeta))(10)-NH(2), and show that a collagen triple-helix structure is only achieved after glycosylation of Thr. Thus, we show for the first time that glycosylation is required for the formation of a stable tertiary structure and that this modification represents an alternative way of stabilizing the collagen triple-helix that is independent of the presence of Hyp.
对于大多数胶原蛋白而言，胶原蛋白三螺旋结构的解链温度（T(m)）与-Gly-Xaa-Yaa-三联体重复序列中Xaa和Yaa位置的脯氨酸（Pro）和4-反式羟脯氨酸（Hyp）的总含量相关。深海热液喷口蠕虫巨型管虫（Riftia pachyptila）的表皮胶原蛋白，尽管Pro和Hyp含量非常低，却具有相对较高的热稳定性。与哺乳动物胶原蛋白中通常的情况不同，在该胶原蛋白中，占据Yaa位置的不是Hyp，而是O-糖基化的苏氨酸（Thr）。我们比较了两种模型肽Ac-(Gly-Pro-Thr)(10)-NH(2)和Ac-(Gly-Pro-Thr(Galβ))(10)-NH(2)在水中形成三螺旋的倾向，并表明只有在Thr糖基化后才能形成胶原蛋白三螺旋结构。因此，我们首次表明糖基化是形成稳定三级结构所必需的，并且这种修饰代表了一种独立于Hyp存在而稳定胶原蛋白三螺旋的替代方式。
