de Bustos Alfredo, Pérez Ruth, Jouve Nicolás
Department of Cell Biology and Genetics, University of Alcalá, Campus Universidad de Alcalá, 28871 Alcalá de Henares (Madrid), Spain.
Theor Appl Genet. 2007 Apr;114(6):985-99. doi: 10.1007/s00122-006-0493-x. Epub 2007 Jan 30.
The MRE11 protein is a component of the highly conserved MRN complex, along with RAD50 and NBS1. This complex is crucial in the repair of breaks in double stranded DNA, and is involved in many other cell processes. The present paper reports the molecular characterization of Mre11 gene in all three genomes of wheat, making use of the diploid species Triticum monococcum (genome A) and Aegilops Tauschii (genome D), the tetraploid T. turgidum (genomes A and B), and the hexaploid T. aestivum (genomes A, B and D). The genomic sequences characterized ranged from 4,662 to 4,766 bp in length; the cDNA corresponding to the processed mRNA was 2,440-2,510 bp long. In all cases, Mre11 coded for a highly conserved protein of 699 amino acids with a structure involving 22 exons. Mre11 expression was determined by real-time PCR in all the species analysed. The tetraploid species showed an expression similar to that of the diploid Ae. tauschii and lower than that of T. monococcum. Stronger expression was detected in the hexaploid T. aestivum. The SSCP technique was modified by introducing fluorescent labelling to the procedure in order to analyse the expression of the different Mre11 genes (i.e., those belonging to the different genomes) in the polyploid species. In both polyploids, the Mre11 gene belonging to the B genome was the least expressed. This probably reflects a first step in the process of silencing duplicate genes after polyploidization.
MRE11蛋白是高度保守的MRN复合物的一个组成部分，与RAD50和NBS1一起。该复合物在双链DNA断裂的修复中至关重要，并参与许多其他细胞过程。本文利用二倍体物种一粒小麦（基因组A）和节节麦（基因组D）、四倍体硬粒小麦（基因组A和B）以及六倍体普通小麦（基因组A、B和D），报道了小麦所有三个基因组中Mre11基因的分子特征。所鉴定的基因组序列长度在4662至4766 bp之间；与加工后的mRNA对应的cDNA长度为2440 - 2510 bp。在所有情况下，Mre11编码一种由699个氨基酸组成的高度保守的蛋白质，其结构包含22个外显子。通过实时PCR测定了所有分析物种中Mre11的表达。四倍体物种的表达与二倍体节节麦相似，低于一粒小麦。在六倍体普通小麦中检测到更强的表达。为了分析多倍体物种中不同Mre11基因（即属于不同基因组的基因）的表达，对SSCP技术进行了改进，在该程序中引入了荧光标记。在两个多倍体中，属于B基因组的Mre11基因表达最少。这可能反映了多倍化后重复基因沉默过程的第一步。
