Destabilization of osteogenesis imperfecta collagen-like model peptides correlates with the identity of the residue replacing glycine
Destabilization of osteogenesis imperfecta collagen-like model peptides correlates with the identity of the residue replacing glycine
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DOI：
10.1073/pnas.070050097
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发表时间：
2000-04-11
影响因子：
11.1
通讯作者：
Brodsky, B
中科院分区：
文献类型：
--
作者：
Beck, K;Chan, VC;Brodsky, B
导致I型胶原蛋白三螺旋的重复（Gly-Xaa-Yaa）（n）三联体模式内的一个专性Gly残基被替换的突变是骨生成紊乱（OI）的主要原因。OI的表型涉及脆弱的骨骼，范围从轻度到围产期致死。在本研究中，使用乙酰基-（Gly-Pro-Hyp）（3）-Zaa-Pro-Hyp-（Gly-Pro-hyp）（4）-Gly-Gly-酰胺形式的宿主-客体三螺旋肽来分离取代Gly的残基对三螺旋稳定性的影响，其中Zaa = Gly、Ala、Arg、Asp、Glu、Cys、ser或瓦尔。Zaa = Gly（解链温度，T-m = 45 ℃）的任何取代导致三螺旋的显著不稳定。对于Ala和ser，T-m降低至约10 ℃，对于含Arg、瓦尔、Glu和Asp的肽，T-m < 0 ℃。Gly-> Cys置换在还原条件下导致T-m < 0 ℃，但在氧化环境中显示宽转变（T-m接近19 ℃）。添加三甲基胺N-氧化物使T-m每1 M三甲基胺N-氧化物增加约5 ℃，导致所有肽形成稳定的三螺旋并允许比较相对稳定性。这些肽中不同Gly置换的破坏顺序可以表示为Ala小于或等于ser < CPOred < Arg <瓦尔< Glu小于或等于Asp。这些富含Gly-ProHyp的同源三聚体肽中Gly取代的不稳定等级显示与I型胶原α 1链中天然OI突变的严重程度显著相关。
Mutations resulting in replacement of one obligate Gly residue within the repeating (Gly-Xaa-Yaa)(n) triplet pattern of the collagen type I triple helix are the major cause of osteogenesis imperfecta (OI). Phenotypes of OI involve fragile bones and range from mild to perinatal lethal. In this study, host-guest triple-helical peptides of the form acetyl-(Gly-Pro-Hyp)(3)-Zaa-Pro-Hyp-(Gly-Pro-hyp)(4)-Gly- Gly-amide are used to isolate the influence of the residue replacing Gly on triple-helix stability, with Zaa = Gly, Ala, Arg, Asp, Glu, Cys, ser, or Val. Any substitution for Zaa = Gly (melting temperature, T-m = 45 degrees C) results in a dramatic destabilization of the triple helix. For Ala and ser, T-m decreases to approximate to 10 degrees C, and for the Arg-, Val-, Glu-, and Asp-containing peptides, T-m < 0 degrees C. A Gly --> Cys replacement results in T-m < 0 degrees C under reducing conditions but shows a broad transition (T-m approximate to 19 degrees C) in an oxidizing environment. Addition of trimethylamine N-oxide increases T-m by approximate to 5 degrees C per 1 M trimethylamine N-oxide, resulting in stable triple-helix formation for all peptides and allowing comparison of relative stabilities. The order of disruption of different Gly replacements in these peptides can be represented as Ala less than or equal to ser < CPOred < Arg < Val < Glu less than or equal to Asp. The rank of destabilization of substitutions for Gly in these Gly-ProHyp-rich homotrimeric peptides shows a significant correlation with the severity of natural OI mutations in the alpha 1 chain of type I collagen.