Characterization of 5’-Noncoding Region of Millet Chloroplast psbA Gene  

粟PsbA基因5’未端非编码区的结构特征

作　　者：黄瑶[1] 吴乃虎[1] 

机构地区：[1]中国科学院发育生物学研究所

出　　处：《Developmental and Reproductive Biology》1995年第2期17-23,共7页发育与生殖生物学报（英文版）

摘　　要：The 2.2 kb EcoRI fragment containing the chloroplast pshA gene from millet (Setaria italica) has been cloned and the nucleotide sequence of the 5’-noncoding region has been determined. The 5’-flanking region is found to contain prokaryote-like promoter structures: compared with prokaryotic promoters, the“-35”box (TTGACA) shows 100% homology while, in the ‘-10’box (TATACT), one different nucleotide is found. In addition, between these two boxes, there is a consensus sequence“TATATA”.just as in prokaryotic promoters. All these results indicate that millet psbA promoter has both prokaryotic and eukaryotic characteristies. The mRNA leader region of millet pshA gene is 87 bp, the same length as sorghum. However, an additional CTATTT sequence is found as compared with rice and an additional TTTT, as with wheat, barley and rye. So the differences between C3 and C4 plants may be universal in the family of Gramineae. Furthermore, computer analysis shows that a small stem-loop structure might be formed in pshA mRNA leader region in these six plants. The above-mentioned additional CTATTT sequence happens to be just located within the stem-loop structure, thus leading to different sizes of the stem-loops among these six species. It is likely that this small secondary structure may have some effect on the expression and regulation of the psbA gene.本文对粟（Ｓｅｔｃｒｉａｉｔａｉｌｉｃａ，俗称：谷子）叶绿体基因ｐｓｂＡ上２２ｋｂ的ＥｃｉＲＩ片段进行了克隆。该基因５’－未端非编码区就位于这个片段上。序列分析显示这个编码区存在着与原核生物基因类似的启动子结构：其“－１０”区序列为ＴＡＴＡＣＴ，与原核生物的仅相差一个核苷酸；“－３５”区序列为ＴＴＧＡＣＡ，与原核生物的完全相同。另一方面，在“－１０”和“－３５”区之间还存在着一个类似真核生物核基因启动子结构的“ＴＡＴＡＴＡ”保守序列。这表明粟ｐｓｂＡ基因的启动子既具有原核基因的特征、又具有真核基因的特征。粟ｐｓｂＡ基因的ｍＲＮＡ前导序多列长８７ｂｐ，与高粱的完全一致。可以推测：禾本科Ｃ３和Ｃ４植物中，ｐｓｂＡ基因ｍＲＮＡ前导序列区的差异可能具有某种普遍性。计算机分析结果显示，６种植物的ｐｓｂＡ基因ｍＲＮＡ前导序列区内均能形成小的茎环结构，而且这段“ＣＴＡＴＴＴＴ”额外序列恰好位于茎环结构中，造成了６种植物间茎环大小的差异。可能，这个小的二级结构对ｐｓｂＡ基因的表达调控有一定的影响。

关 键 词：MILLET PSBA PROMOTER Stem-loop structure. 

分 类 号：Q943[生物学—植物学] S515[农业科学—作物学]