Venegas Juan A, Aslund Lena, Solari Aldo
Programa de Biología Celular y Molecular, ICBM, Universidad de Chile, Casilla 70086, Santiago-7, Chile.
Parasitol Int. 2009 Jun;58(2):187-92. doi: 10.1016/j.parint.2009.01.007. Epub 2009 Feb 3.
A gene coding for a DNA polymerase beta from the Trypanosoma cruzi Miranda clone, belonging to the TcI lineage, was cloned (Miranda Tcpol beta), using the information from eight peptides of the T. cruzi beta-like DNA polymerase purified previously. The gene encodes for a protein of 403 amino acids which is very similar to the two T. cruzi CL Brener (TcIIe lineage) sequences published, but has three different residues in highly conserved segments. At the amino acid level, the identity of TcI-pol beta with mitochondrial pol beta and pol beta-PAK from other trypanosomatids was between 68-80% and 22-30%, respectively. Miranda Tc-pol beta protein has an N-terminal sequence similar to that described in the mitochondrial Crithidia fasciculata pol beta, which suggests that the TcI-pol beta plays a role in the organelle. Northern and Western analyses showed that this T. cruzi gene is highly expressed both in proliferative and non-proliferative developmental forms. These results suggest that, in addition to replication of kDNA in proliferative cells, this enzyme may have another function in non-proliferative cells, such as DNA repair role similar to that which has extensively been described in a vast spectrum of eukaryotic cells.
利用先前纯化的克氏锥虫β样DNA聚合酶的8个肽段的信息，克隆了来自克氏锥虫米兰达克隆株（属于TcI谱系）的编码DNA聚合酶β的基因（米兰达Tcpolβ）。该基因编码一个由403个氨基酸组成的蛋白质，它与已发表的两个克氏锥虫CL Brener（TcIIe谱系）序列非常相似，但在高度保守的区段有三个不同的残基。在氨基酸水平上，TcI - polβ与其他锥虫的线粒体polβ和polβ - PAK的同一性分别在68 - 80%和22 - 30%之间。米兰达Tc - polβ蛋白的N端序列与线粒体纤细无口锥虫polβ中描述描述的序列相似，这表明TcI - polβ在细胞器中发挥作用。Northern和Western分析表明，该克氏锥虫基因在增殖性和非增殖性发育形式中均高度表达。这些结果表明，除了在增殖细胞中参与kDNA的复制外，这种酶在非增殖细胞中可能还有其他功能，如类似于在广泛的真核细胞中已被大量描述的DNA修复作用。
