Yang P, Taoka K, Nakayama T, Iwabuchi M
Department of Botany, Faculty of Science, Kyoto University, Japan.
Plant Mol Biol. 1995 Apr;28(1):155-72. doi: 10.1007/BF00042047.
Two wheat histone H2B genes (TH123 and TH153) were isolated. Nucleotide sequence analysis revealed that some characteristic sequence motifs were conserved in both the 5'- and 3'-flanking regions. A canonical TATA box and several CCAAT sequences were present in the presumed promoter regions. Motifs similar or identical to the hexamer (ACGTCA) and octamer (CGCGGATC) motifs that are positive cis-acting elements of the wheat H3 (TH012) promoter were also observed in both the H2B promoters. A gel mobility shift assay indicated that the hexamer and hexamer-like motifs bound the wheat bZIP proteins HBP-1a and/or HBP-1b in vitro. A novel sequence motif, (A/T)(G/A)AAAT(A/G), was found downstream of a translational stop codon as observed in several plant histone H2B cDNAs. Promoter activity was analyzed with H2B promoter-GUS fusion genes in the transient system using tobacco protoplasts. Studies of the promoter function in transgenic tobacco plants showed that the H2B promoters were preferentially active in meristematic tissues. Taken together, our data indicate that the H2B genes are regulated, in part, by the same mechanism as found in H3 and H4 gene transcription.
分离出了两个小麦组蛋白H2B基因（TH123和TH153）。核苷酸序列分析表明，一些特征性序列基序在5'和3'侧翼区域均保守。在推测的启动子区域存在一个典型的TATA盒和几个CCAAT序列。在H2B启动子中也观察到与小麦H3（TH012）启动子的正向顺式作用元件六聚体（ACGTCA）和八聚体（CGCGGATC）基序相似或相同的基序。凝胶迁移率变动分析表明，六聚体和六聚体样基序在体外与小麦bZIP蛋白HBP-1a和/或HBP-1b结合。如在几个植物组蛋白H2B cDNA中所观察到的，在翻译终止密码子下游发现了一个新的序列基序（A/T）（G/A）AAAT（A/G）。使用烟草原生质体在瞬时系统中用H2B启动子-GUS融合基因分析启动子活性。对转基因烟草植株中启动子功能的研究表明，H2B启动子在分生组织中优先活跃。综上所述，我们的数据表明，H2B基因部分受与H3和H4基因转录中发现的相同机制调控。
