• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >Structure and function in bacteriorhodopsin: The role of the interhelical loops in the folding and stability of bacteriorhodopsin
【24h】

Structure and function in bacteriorhodopsin: The role of the interhelical loops in the folding and stability of bacteriorhodopsin

机译：细菌视紫红质的结构和功能：螺旋间环在细菌视紫红质的折叠和稳定性中的作用

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Bacteriorhodospin functions as a light-driven proton pump in Halobacterium salinarium. The functional protein consists of an apoprotein, bacterioopsin, with seven transmembrane alpha helices together with a covalently bound all-trans retinal chromophore. In order to study the role of the interhelical loop conformations in the structure and function of bacteriorhodopsin, we have constructed bacterioopsin genes where each loop is replaced, one at a time, by a peptide linker consisting of Gly-Gly-Ser-repeat sequences, which are believed to have flexible conformations. These mutant proteins have been expressed in Escherichia coli, purified and reconstituted with all-trans retinal in L-alpha -1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/3-(3-cholamidopropyl)dimethylammonio-1-propane sulfonate (CHAPS)/SDS and L-alpha -1,2-dihexanoylphosphatidylcholine (DHPC)/DMPC/SDS micelles. Wild-type-like chromophore formation was observed in all the mutants containing single loop replacements. In the BC and FG mutants, an additional chromophore band with an absorption band at about 480 nm was observed, which was in equilibrium with the 550 nm, wild-type band. The position of the equilibrium depended on temperature, SDS and relative DMPC concentration. The proton pumping activity of all of the mutants was comparable to that of wild-type bR except for the BC and FG mutants, which had lower activity. All of the loop mutants were more sensitive to denaturation by SDS than the wild-type protein, except the mutant where the DE loop was replaced. These results suggest that a specific conformation of all the loops of bR, except the DB loop, contributes to bR stability and is required for the correct folding and function of the protein. An increase in the relative proportion of DHPC in DHPC/DMPC micelles, which reduces the micelle rigidity and alters the micelle shape, resulted in lower folding yields of all loop mutants except the BC and DE: mutants. This effect of micelle rigidity on the bR folding yield correlated with a loss in stability of a partially folded, seven-transmembrane apoprotein intermediate state in SDS/DMPC/CHAPS micelles. The folding yield and stability of the apoprotein intermediate state both decreased for the loop mutants in the order WT similar to BC similar to DE > FG > AB > EF greater than or equal to CD, where the EF and CD loop mutants were the least stable. (C) 2001 Academic Press. [References: 39]
机译：Bacteriorhodospin在盐杆菌中起着光驱动质子泵的作用。功能蛋白由载脂蛋白，细菌球蛋白和七个跨膜α螺旋以及共价结合的全反式视网膜生色团组成。为了研究螺旋间环构象在细菌视紫红质的结构和功能中的作用，我们构建了细菌球蛋白基因，每个环一次被一个由Gly-Gly-Ser-重复序列组成的肽接头取代，被认为具有灵活的构象。这些突变蛋白已在大肠杆菌中表达，纯化并在L-α-1,2-二肉豆蔻酰基-sn-甘油-3-磷酸胆碱（DMPC）/ 3-（3-胆酰胺丙基）二甲基铵1中经全反式视网膜重构-丙烷磺酸盐（CHAPS）/ SDS和L-α-1,2-二己酰基磷脂酰胆碱（DHPC）/ DMPC / SDS胶束。在所有包含单环置换的突变体中均观察到了野生型样发色团的形成。在BC和FG突变体中，观察到另一个发色团带，其吸收带约为480 nm，与550 nm野生型带处于平衡状态。平衡的位置取决于温度，SDS和相对DMPC浓度。除BC和FG突变体的活性较低外，所有突变体的质子泵送活性均与野生型bR相当。除替换DE环的突变体外，所有环突变体均比野生型蛋白对SDS变性更敏感。这些结果表明，除了DB环之外，bR的所有环的特定构象有助于bR的稳定性，并且是蛋白质正确折叠和功能所必需的。 DHPC / DMPC胶束中DHPC相对比例的增加，降低了胶束的刚度并改变了胶束的形状，导致除BC和DE：突变体以外的所有环状突变体的折叠产率较低。胶束刚度对bR折叠产量的影响与SDS / DMPC / CHAPS胶束中部分折叠的七跨膜载脂蛋白中间状态稳定性的损失有关。对于环状突变体，脱辅基蛋白中间态的折叠产量和稳定性均以WT类似于BC的顺序降低，类似于DE> FG> AB> EF大于或等于CD，其中EF和CD环状突变体的稳定性最差。 （C）2001学术出版社。 [参考：39]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号