Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil.
Mol Biol Rep. 2012 Jun;39(6):6513-9. doi: 10.1007/s11033-012-1479-1. Epub 2012 Feb 4.
Cassava (Manihot esculenta Crantz) is one of the world's most important food crops. It is cultivated mainly in developing countries of tropics, since its root is a major source of calories for low-income people due to its high productivity and resistance to many abiotic and biotic factors. A previous study has identified a partial cDNA sequence coding for a putative RING zinc finger in cassava storage root. The RING zinc finger protein is a specialized type of zinc finger protein found in many organisms. Here, we isolated the full-length cDNA sequence coding for M. esculenta RZF (MeRZF) protein by a combination of 5' and 3' RACE assays. BLAST analysis showed that its deduced amino acid sequence has a high level of similarity to plant proteins of RZF family. MeRZF protein contains a signature sequence motif for a RING zinc finger at its C-terminal region. In addition, this protein showed a histidine residue at the fifth coordination site, likely belonging to the RING-H2 subgroup, as confirmed by our phylogenetic analysis. There is also a transmembrane domain in its N-terminal region. Finally, semi-quantitative RT-PCR assays showed that MeRZF expression is increased in detached leaves treated with sodium chloride. Here, we report the first evidence of a RING zinc finger gene of cassava showing potential role in response to salt stress.
木薯（Manihot esculenta Crantz）是世界上最重要的粮食作物之一。它主要在热带发展中国家种植，因为其根部产量高，并且对许多非生物和生物因素具有抗性，所以是低收入人群的主要热量来源。先前的一项研究已经鉴定出木薯贮藏根中一个假定的 RING 锌指的部分 cDNA 序列。RING 锌指蛋白是在许多生物体中发现的一种特殊类型的锌指蛋白。在这里，我们通过 5' 和 3' RACE 测定法组合，分离出编码 M. esculenta RZF（MeRZF）蛋白的全长 cDNA 序列。BLAST 分析表明，其推导的氨基酸序列与 RZF 家族的植物蛋白具有高度相似性。MeRZF 蛋白在其 C 末端区域含有 RING 锌指的特征序列基序。此外，通过系统进化分析证实，该蛋白在第五个配位位点具有组氨酸残基，可能属于 RING-H2 亚组。在其 N 末端区域也有一个跨膜结构域。最后，半定量 RT-PCR 分析表明，MeRZF 的表达在经氯化钠处理的离体叶片中增加。在这里，我们首次报道了木薯 RING 锌指基因在应对盐胁迫方面的潜在作用。
