A cold-regulated nucleic acid-binding protein of winter wheat shares a domain with bacterial cold shock proteins
A cold-regulated nucleic acid-binding protein of winter wheat shares a domain with bacterial cold shock proteins
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DOI：
10.1074/jbc.m205774200
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发表时间：
2002-09-20
影响因子：
4.8
通讯作者：
Imai, R
中科院分区：
文献类型：
--
作者：
Karlson, D;Nakaminami, K;Imai, R
冷驯化的分子机制仍然很大程度上是未知的；然而，已经确定，冬小麦等越冬植物在冷处理期间提高了耐寒性。在原核生物中，冷休克蛋白是由温度下降诱导的，并被认为是作为RNA伴侣的功能。从小麦中分离到一个编码核酸结合蛋白WCSP1的基因，该基因与大肠杆菌主要的CSPA基因同源。推测的WCSP1蛋白含有一个由N端冷休克结构域和两个内部保守的一致RNA结合区组成的三个结构域，以及一个内部富含甘氨酸的区域，该区域点缀着三个C端的CX2CX4HX4C(CCHC)锌指。每个结构域在几个核苷酸结合蛋白中都有独立的描述。Northern和Western印迹分析表明，在冷驯化过程中，WCSP1的mRNA和蛋白水平分别稳步上升。WCSP1的诱导是冷特异的，因为脱落酸处理、干旱、盐分和热胁迫都不能诱导WCSP1的表达。核苷酸结合分析表明，WCSP1与ssDNA、dsDNA和RNA均聚体结合。在缺乏C-末端锌指的突变蛋白中，结合dsDNA的能力几乎被消除。WCSP1与大肠杆菌CSPA在结构和表达上的相似性表明，WCSP1可能参与了冷驯化过程中的基因调控。
The molecular mechanisms of cold acclimation are still largely unknown; however, it has been established that overwintering plants such as winter wheat increases freeze tolerance during cold treatments. In prokaryotes, cold shock proteins are induced by temperature downshifts and have been proposed to function as RNA chaperones. A wheat cDNA encoding a putative nucleic acid-binding protein, WCSP1, was isolated and found to be homologous to the predominant CspA of Escherichia coli. The putative WCSP1 protein contains a three-domain structure consisting of an N-terminal cold shock domain with two internal conserved consensus RNA binding domains and an internal glycine-rich region, which is interspersed with three C-terminal CX2CX4HX4C (CCHC) zinc fingers. Each domain has been described independently within several nucleotide-binding proteins. Northern and Western blot analyses showed that WCSP1 mRNA and protein levels steadily increased during cold acclimation, respectively. WCSP1 induction was cold-specific because neither abscisic acid treatment, drought, salinity, nor heat stress induced WCSP1 expression. Nucleotide binding assays determined that WCSP1 binds ssDNA, dsDNA, and RNA homopolymers. The capacity to bind dsDNA was nearly eliminated in a mutant protein lacking C-terminal zinc fingers. Structural and expression similarities to E. coli CspA suggest that WCSP1 may be involved in gene regulation during cold acclimation.