WRKY蛋白结构域

WRKY结构域是一类转录因子，存在于WRKY转录因子家族中Rushton, Torres, Parniske, Wernert, Hahlbrock, et al. (1996) Interaction of elicitor-induced DNA-binding proteins with elicitor response elements in the promoters of parsley PR1 genes. The EMBO Journal. 15(20). 5690, Eulgem, Rushton, Robatzek and Somssich (2000) The WRKY superfamily of plant transcription factors. Trends in Plant Science. 5(5). 199-206。几乎所有植物基因组中都有带WRKY结构域的蛋白，同时WRKY基因也被发现存在于双滴虫、多细胞变形虫及其他变形虫门和一些真菌基因组中。不过WRKY基因似乎不存在于一些其他的非植物物种。在过去的20年间，WRKY转录因子一直是植物学领域的重点研究对象Schluttenhofer and Yuan (2014) Regulation of Specialized Metabolism by WRKY Transcription Factors. Plant Physiology, Bakshi and Oelmüller (2014) WRKY transcription factors: Jack of many trades in plants. Plant Signaling & Behavior. 9(1). e27700。WRKY的DNA识别结构域能够识别W-box顺式作用元件(T)TGAC(C/T)，以及W-box序列的一些变体。

 结构 
WRKY转录因子含有一个或两个WRKY蛋白结构域。 WRKY蛋白结构域是一个长度为60到70个氨基酸的DNA结合结构域。该结构域的主要特征是一个高度保守的WRKYGQK模序和一个锌指区域。 半胱氨酸和组氨酸锌指结构域是CX4-5CX22-23HXH或CX7CX23HXC类型的，其中X可以是任何氨基酸。 Eulgem, Rushton, Robatzek and Somssich (2000) The WRKY superfamily of plant transcription factors. Trends in Plant Science. 5(5). 199-206锌指结合Zn2+离子来满足蛋白质功能的需要。Yamasaki, Kigawa, Inoue, Tateno, Yamasaki, et al. (2005) Solution Structure of an Arabidopsis WRKY DNA Binding Domain. The Plant Cell. 17(3). 944-956尽管WRKYGQK序列在大多数WRKY结构域中是高度保守的，但是也有文献记载核心序列是存在差异化的。 Schluttenhofer and Yuan (2014) Regulation of Specialized Metabolism by WRKY Transcription Factors. Plant Physiology, Zhang and Wang (2005) The WRKY transcription factor superfamily: its origin in eukaryotes and expansion in plants. BMC Evolutionary Biology. 5(1). 1核心序列的一种常见的变体是WRKYGKK，存在于大多数植物物种中。Eulgem, Rushton, Robatzek and Somssich (2000) The WRKY superfamily of plant transcription factors. Trends in Plant Science. 5(5). 199-206, Schluttenhofer and Yuan (2014) Regulation of Specialized Metabolism by WRKY Transcription Factors. Plant Physiology, Zhang and Wang (2005) The WRKY transcription factor superfamily: its origin in eukaryotes and expansion in plants. BMC Evolutionary Biology. 5(1). 1, Song, Wang, Nan and Wang (2014) The WRKY Transcription Factor Genes in Lotus japonicus. International Journal of Genomics. 2014(15, Xiong, Xu, Zhang, Wu, Chen, et al. (2013) Genome-wide analysis of the WRKY gene family in physic nut (Jatropha curcas L.). Gene. 524(2). 124-132

WRKY蛋白结构域的结构由2005年的核磁共振（NMR）和后来的结晶学所确定。Yamasaki, Kigawa, Inoue, Tateno, Yamasaki, et al. (2005) Solution Structure of an Arabidopsis WRKY DNA Binding Domain. The Plant Cell. 17(3). 944-956, Duan, Nan, Liang, Mao, Lu, et al. (2007) DNA binding mechanism revealed by high resolution crystal structure of Arabidopsis thaliana WRKY1 protein. Nucleic Acids Research. 35(4). 1145-1154WRKY蛋白结构域是由五条反平行β-链组成的球形蛋白。核心的WRKYGQK模序位于第二个β链上。Duan, Nan, Liang, Mao, Lu, et al. (2007) DNA binding mechanism revealed by high resolution crystal structure of Arabidopsis thaliana WRKY1 protein. Nucleic Acids Research. 35(4). 1145-115418个氨基酸在WRKY蛋白结构域中是高度保守的，包括核心基序，锌指结合的半胱氨酸和组氨酸和形成DWK盐桥的三联体。三联体由位于核心模序的保守色氨酸（W）、四个氨基酸前的天冬氨酸（D）和29个氨基酸后的赖氨酸（K）组成，这个组合稳定了整个结构域。第三个β-链上的五个氨基酸（PRSYY）在WRKY结构域中也很保守。重要的是，WRKY基因在WRKY结构域中含有一个保守的内含子，它发生在编码PRSYY氨基酸序列PR的位置。这就解释了该基序的保守性。

 转录因子-DNA相互作用 
WRKY结构域形成了一个垂直进入DNA链的主沟的独特楔形结构。 Yamasaki, Kigawa, Watanabe, Inoue, Yamasaki, et al. (2012) Structural Basis for Sequence-specific DNA Recognition by an Arabidopsis WRKY Transcription Factor. Journal of Biological Chemistry. 287(10). 7683-7691WRKY蛋白结构域与（T / A）TGAC（T / A）顺式元件（也称为W-Box）存在着相互作用。Rushton, Torres, Parniske, Wernert, Hahlbrock, et al. (1996) Interaction of elicitor-induced DNA-binding proteins with elicitor response elements in the promoters of parsley PR1 genes. The EMBO Journal. 15(20). 5690, Eulgem, Rushton, Schmelzer, Hahlbrock and Somssich (1999) Early nuclear events in plant defence signalling: rapid gene activation by WRKY transcription factors. EMBO J. 18(17). 4689-4699, De Pater, Greco, Pham, Memelink and Kijne (1996) Characterization of a Zinc-Dependent Transcriptional Activator from Arabidopsis. Nucleic Acids Research. 24(23). 4624-4631最近的证据表明，W-Box的GAC核心是WRKY结构域的主要作用位点，侧翼序列有助于调控DNA与特异性的WRKY蛋白之间的相互作用。Brand, Fischer, Harter, Kohlbacher and Wanke (2013) Elucidating the evolutionary conserved DNA-binding specificities of WRKY transcription factors by molecular dynamics and in vitro binding assays. Nucleic Acids Research. 41(21). 9764-9778核心模序的RKYGQK残基和WRKY结构域中的精氨酸与赖氨酸残基负责与七个连续DNA碱基对（包括GAC核心）的磷酸骨架相互作用。Yamasaki, Kigawa, Watanabe, Inoue, Yamasaki, et al. (2012) Structural Basis for Sequence-specific DNA Recognition by an Arabidopsis WRKY Transcription Factor. Journal of Biological Chemistry. 287(10). 7683-7691, Brand, Fischer, Harter, Kohlbacher and Wanke (2013) Elucidating the evolutionary conserved DNA-binding specificities of WRKY transcription factors by molecular dynamics and in vitro binding assays. Nucleic Acids Research. 41(21). 9764-9778将色氨酸，酪氨酸或WRKYGQK模序的赖氨酸突变为丙氨酸则会使蛋白无法与DNA结合，这个情况表明这些氨基酸对于识别W-Box序列是必不可少的。Duan, Nan, Liang, Mao, Lu, et al. (2007) DNA binding mechanism revealed by high resolution crystal structure of Arabidopsis thaliana WRKY1 protein. Nucleic Acids Research. 35(4). 1145-1154, Maeo, Hayashi, Kojima-Suzuki, Morikami and Nakamura (2001) Role of conserved residues of the WRKY domain in the DNA-binding of tobacco WRKY family proteins. Bioscience, Biotechnology, and Biochemistry. 65(11). 2428-2436尽管不是必要的，当用丙氨酸突变掉WRKYGQK模序中的精氨酸，甘氨酸或谷氨酰胺时，可以减少与W-Box的结合。总的来说，WRKY蛋白结构域与DNA的复杂的相互作用会在植物生长发育和抵抗外界胁迫时，起到激活有关基因的作用。

 参考文献 

Category:2005年科學
Category:植物蛋白质
Category:蛋白质域