Association of Palm gene mutations with structure and function of paralemmin proteins in Lori-Bakhtiari and Zel sheep Breeds

ABSTRACT. The aim of current study was to survey genetic variability of PALM gene’s exon 3 and 4 by PCR-SSCP and DNA sequencing in Zel and Lori Bakhtiari sheep breeds. The SIFT (Sorting Intolerant from Tolerant) and PHyre2 program were used to predict the possible impact of amino acid substitutions on performance and structure of the paralemmin protein. A total of 140 animal's from 2 Iranian sheep breeds with different fat metabolisms, Lori-Bakhtiari and Zel sheep breeds were considered. The results showed that there are two polymorphic sites including a nonsynonymous substitution and an insertion mutation (49bp). Non-synonymous mutation deduced Thr20Ala amino acid exchange and ensuing two different structures for paralemmin protein that could be potentially affect protein structure and function during the interaction with glutamate in the cytosolic surface of plasma membrane. PALM gene, according to evolutionary path, is classified into two separate categories. In first covey, Gallus gallus and in second one, other species in several branches, so that the sequence of cow and sheep is placed in a sub-branch which forms a clade beside goat. Comparison of illustrated coding region sequences, PALM gene among different species, is of orthologous which are derived from a common ancestor.

摘要：本研究旨在通过聚合酶链反应-单链构象多态性（PCR-SSCP）结合DNA测序技术，分析泽尔羊（Zel）与洛里巴赫蒂亚里羊（Lori Bakhtiari）两个伊朗绵羊品种中PALM基因第3、4外显子的遗传变异情况。本研究采用SIFT（Sorting Intolerant from Tolerant）工具与PHyre2程序，预测氨基酸替换对Paralemmin蛋白的功能与结构的潜在影响。本研究共纳入140只个体，来自2个脂肪代谢特性存在差异的伊朗绵羊品种——洛里巴赫蒂亚里羊与泽尔羊。研究结果显示，共存在2个多态位点：1个错义突变位点与1个49bp的插入突变位点。该错义突变导致第20位氨基酸发生苏氨酸到丙氨酸的替换（Thr20Ala），并使Paralemmin蛋白形成两种不同的空间构象，这一变化可能在蛋白与质膜胞质侧谷氨酸的相互作用过程中，对蛋白的结构与功能产生潜在影响。PALM基因依据进化路径可分为两个独立的单系群：第一类仅包含原鸡（Gallus gallus），第二类则涵盖多个分支的其他物种，其中牛与绵羊的序列处于同一亚分支，并与山羊序列共同构成一个独立的单系支。对不同物种PALM基因编码区序列的比较分析显示，该基因属于直系同源基因，起源于共同的祖先序列。