FUNCTIONAL DIVERSIFICATION AND EVOLUTION OF ANTIFREEZE PROTEINS

抗冻蛋白的功能多样化和进化

• 批准号: 8365846
• 负责人: WILLIE J SWANSON
• 金额: $ 0.65万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8365846
• 关键词: Antarctic; Antifreeze Proteins; Arctic Regions; Base Pairing; Binding; Biology; Depressed mood; Eels; Evolution; Expressed Sequence Tags; Fishes; Freezing; Funding; Fungal Genome; Genome; Grant; Ice; Individual; Libraries; Liver; Molecular; Molecular Evolution; National Center for Research Resources; Organism; Peptide Signal Sequences; Principal Investigator; Protein Isoforms; Proteins; Proteomics; Research; Research Infrastructure; Resources; Serum; Source; Techniques; Terminator Codon; Translating; Type III Antifreeze Proteins; United States National Institutes of Health; Variant; cost; dimer; monomer; paralogous gene

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Antifreeze proteins (AFPs) have independently evolved in many organisms. AFPs act by binding to ice crystals, effectively lowering the freezing point. AFPs are often at high copy number in a genome and diversity exists between copies. Type III antifreeze proteins are found in Arctic and Antarctic eel pouts, and have previously been shown to evolve under positive selection. Here we combine molecular and proteomic techniques to understand the molecular evolution and diversity of Type III antifreeze proteins in a single individual Antarctic fish Lycodichthys dearborni. Our expressed sequence tag (EST) screen reveals that at least seven different AFP variants are transcribed, which are ultimately translated into five different protein isoforms. The isoforms have identical 66 base pair signal sequences and different numbers of subsequent ice-binding domains followed by a stop codon. Isoforms with one ice-binding unit (monomer), two units (dimer), and multiple units (multimer) were present in the EST library. We identify a previously uncharacterized protein dimer, providing further evidence that there is diversity between Type III AFP isoforms, perhaps driven by positive selection for greater thermal hysteresis. Proteomic analysis confirms that several of these isoforms are translated and present in the liver. Our molecular evolution study shows that paralogs have diverged under positive selection. We hypothesize that antifreeze protein diversity is an important contributor to depressing the serum freezing point.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的首席研究员可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 抗冻蛋白（AFP）在许多生物体中独立进化。 AFP 通过与冰晶结合来发挥作用，有效降低冰点。 AFP 在基因组中通常具有高拷贝数，并且拷贝之间存在多样性。 III 型抗冻蛋白存在于北极和南极鳗鲡中，此前已被证明在正选择下进化。在这里，我们结合分子和蛋白质组学技术来了解单个南极鱼 Lycodichthys Dearborni 中 III 型抗冻蛋白的分子进化和多样性。我们的表达序列标签 (EST) 筛选显示至少有 7 种不同的 AFP 变体被转录，最终被翻译成 5 种不同的蛋白质亚型。这些异构体具有相同的 66 个碱基对信号序列和不同数量的后续冰结合结构域，后跟终止密码子。 EST 文库中存在具有一个冰结合单元（单体）、两个单元（二聚体）和多个单元（多聚体）的异构体。我们鉴定了一种先前未表征的蛋白质二聚体，进一步证明 III 型 AFP 亚型之间存在多样性，这可能是由更大的热滞后的正选择驱动的。蛋白质组学分析证实，其中几种异构体被翻译并存在于肝脏中。我们的分子进化研究表明，旁系同源物在正选择下发生了分化。我们假设抗冻蛋白多样性是降低血清冰点的重要因素。