Navid Afifa, Khan Mohammad Haroon, Rashid Hamid
Department of Bioinformatics, Mohammad Ali Jinnah University, Islamabad, Pakistan.
Bioinformation. 2012;8(5):221-4. doi: 10.6026/97320630008221. Epub 2012 Mar 17.
Hutchinson-Gilford progeria syndrome (HGPS) is caused by de novo dominant point mutations of the genes encoding nuclear lamina proteins, leading towards premature aging. A protein sequence is subjected to mutations in nature which can affect the function and folding pattern of the protein by different ways. Mutations involved in HGPS were identified and were substituted in the seed sequence retrieved from the UniProt database to get the mutated versions. Tertiary structure of the Lamin A protein was previously unpredicted so was performed for all the mutated as well as for the seed protein to analyze the effects of mutations on the protein structure, folding and interactions. All the predicted models were refined and validated through multiple servers for multiple parameters. The validated 3D structure of seed protein was then successfully submitted to the Protein Model Database and was assigned with the PMDB ID PM0077829. All the predicted structures were superimposed with a root mean square deviation value of 7.0 Å and a high Dali Z-score of 1.9. It was observed that mutations affected physiochemical properties as well as instability index and thus is affecting the domains in specific and the whole structure in general. It was further analyzed that HGPS is the result of affected Lamin a protein interactions with other integral and binding proteins in the inner nuclear membrane affecting the link in between the nuclear membrane and the network of the lamina.
哈钦森-吉尔福德早衰综合征(HGPS)由编码核纤层蛋白的基因发生新生显性点突变引起,导致早衰。蛋白质序列在自然状态下会发生突变,这些突变可通过不同方式影响蛋白质的功能和折叠模式。已鉴定出与HGPS相关的突变,并将其替换到从UniProt数据库检索到的种子序列中,以获得突变版本。此前未预测到核纤层蛋白A的三级结构,因此对所有突变蛋白以及种子蛋白进行了预测,以分析突变对蛋白质结构、折叠和相互作用的影响。所有预测模型都通过多个服务器针对多个参数进行了优化和验证。然后将经过验证的种子蛋白三维结构成功提交到蛋白质模型数据库,并被赋予PMDB ID PM0077829。所有预测结构进行了叠加,均方根偏差值为7.0 Å,达利Z分数较高,为1.9。研究发现,突变影响了理化性质以及不稳定指数,从而影响了特定结构域和整体结构。进一步分析表明,HGPS是受影响的核纤层蛋白A与内核膜中其他整合蛋白和结合蛋白相互作用的结果,影响了核膜与核纤层网络之间的联系。