Nijhawan Aashima, Jain Mukesh, Tyagi Akhilesh K, Khurana Jitendra P
Interdisciplinary Centre for Plant Genomics and Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
Plant Physiol. 2008 Feb;146(2):333-50. doi: 10.1104/pp.107.112821. Epub 2007 Dec 7.
The basic leucine (Leu) zipper (bZIP) proteins compose a family of transcriptional regulators present exclusively in eukaryotes. The bZIP proteins characteristically harbor a bZIP domain composed of two structural features: a DNA-binding basic region and the Leu zipper dimerization region. They have been shown to regulate diverse plant-specific phenomena, including seed maturation and germination, floral induction and development, and photomorphogenesis, and are also involved in stress and hormone signaling. We have identified 89 bZIP transcription factor-encoding genes in the rice (Oryza sativa) genome. Their chromosomal distribution and sequence analyses suggest that the bZIP transcription factor family has evolved via gene duplication. The phylogenetic relationship among rice bZIP domains as well as with bZIP domains from other plant bZIP factors suggests that homologous bZIP domains exist in plants. Similar intron/exon structural patterns were observed in the basic and hinge regions of their bZIP domains. Detailed sequence analysis has been done to identify additional conserved motifs outside the bZIP domain and to predict their DNA-binding site specificity as well as dimerization properties, which has helped classify them into different groups and subfamilies, respectively. Expression of bZIP transcription factor-encoding genes has been analyzed by full-length cDNA and expressed sequence tag-based expression profiling. This expression profiling was complemented by microarray analysis. The results indicate specific or coexpression patterns of rice bZIP transcription factors starting from floral transition to various stages of panicle and seed development. bZIP transcription factor-encoding genes in rice also displayed differential expression patterns in rice seedlings in response to abiotic stress and light irradiation. An effort has been made to link the structure and expression pattern of bZIP transcription factor-encoding genes in rice to their function, based on the information obtained from our analyses and earlier known results. This information will be important for functional characterization of bZIP transcription factors in rice.
碱性亮氨酸拉链（bZIP）蛋白构成了一个仅存在于真核生物中的转录调节因子家族。bZIP蛋白的特征是具有一个由两个结构特征组成的bZIP结构域：一个DNA结合碱性区域和亮氨酸拉链二聚化区域。它们已被证明可调节多种植物特有的现象，包括种子成熟和萌发、花诱导和发育以及光形态建成，并且还参与胁迫和激素信号传导。我们在水稻（Oryza sativa）基因组中鉴定出了89个编码bZIP转录因子的基因。它们的染色体分布和序列分析表明，bZIP转录因子家族是通过基因复制进化而来的。水稻bZIP结构域之间以及与其他植物bZIP因子的bZIP结构域之间的系统发育关系表明，同源bZIP结构域存在于植物中。在其bZIP结构域的碱性和铰链区域观察到了相似的内含子/外显子结构模式。已进行了详细的序列分析，以鉴定bZIP结构域之外的其他保守基序，并预测它们的DNA结合位点特异性以及二聚化特性，这有助于分别将它们分类为不同的组和亚家族。已通过基于全长cDNA和表达序列标签的表达谱分析对编码bZIP转录因子的基因的表达进行了分析。这种表达谱分析通过微阵列分析得到了补充。结果表明，从花转变到穗和种子发育的各个阶段，水稻bZIP转录因子具有特定的或共表达模式。水稻中编码bZIP转录因子的基因在水稻幼苗中对非生物胁迫和光照也表现出差异表达模式。基于我们的分析和早期已知结果所获得的信息，已努力将水稻中编码bZIP转录因子的基因的结构和表达模式与其功能联系起来。这些信息对于水稻中bZIP转录因子的功能表征将是重要的。
