The Nature of Nucleotide Sequence Divergence between Barley and Maize Chloroplast DNA.
The Nature of Nucleotide Sequence Divergence between Barley and Maize Chloroplast DNA.
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DOI：
10.1093/genetics/106.4.735
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发表时间：
1984-04
期刊：
影响因子：
3.3
通讯作者：
G. Zurawski;M. Clegg;A. Brown
中科院分区：
文献类型：
--
作者：
G. Zurawski;M. Clegg;A. Brown
对大麦叶绿体DNA的2175个碱基对的SmaI-HindIII片段的分析表明，rbcL(核酮糖1，5-二磷酸羧基酶的大亚基基因)和atpB(ATPase的β亚基基因)是差异转录的，并被155-166个核苷酸的非转录区域分开。RbcL基因有一个320个残基的未翻译前导区，而atpB基因有一个296到309个残基的前导区。将这些区域的序列，连同atpB编码区的起始113bp和rbcL编码区的起始1279bp，与类似的玉米叶绿体DNA序列进行比较。存在两类核苷酸差异，即替换和插入/缺失。核苷酸替换对rbcL编码区的转换有1.9倍的偏向，对非编码区的转换有1.5倍的偏向。大麦和玉米序列之间的核苷酸替换水平约为0.065个/bp。RbcL-编码区71%的替换位于第三密码子位置，其中95%是同义改变。局限于非编码区的插入/缺失事件在这些区域中不是随机分布的，并且通常与短重复序列相关联。非编码区的改变程度(约0.093个事件/个碱基)小于包括插入/缺失事件在内的RBCL编码区中第三个密码子位置的改变程度(约0.135个事件/个碱基)。对野生品系(大麦)和原始伊朗大麦(普通大麦)的相似DNA进行的有限序列分析表明，叶绿体DNA的进化率很低。与菠菜叶绿体DNA相比，大麦rbcL-atpB非翻译区差异很大，只有rbcL启动子和核糖体结合位点被广泛保守。
Analysis of a 2175-base pair (bp) SmaI-HindIII fragment of barley chloroplast DNA revealed that rbcL (the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase) and atpB (the gene for the beta subunit of ATPase) are transcribed divergently and are separated by an untranscribed region of 155-166 bp. The rbcL mRNA has a 320-residue untranslated leader region, whereas the atpB mRNA has a 296- to 309-residue leader region. The sequence of these regions, together with the initial 113 bp of the atpB-coding region and the initial 1279 bp of the rbcL-coding region, is compared with the analogous maize chloroplast DNA sequences. Two classes of nucleotide differences are present, substitutions and insertions/deletions. Nucleotide substitutions show a 1.9-fold bias toward transitions in the rbcL-coding region and a 1.5-fold bias toward transitions in the noncoding region. The level of nucleotide substitutions between the barley and maize sequences is about 0.065/bp. Seventy-one percent of the substitutions in the rbcL-coding region are at the third codon position, and 95% of these are synonymous changes. Insertion/deletion events, which are confined to the noncoding regions, are not randomly distributed in these regions and are often associated with short repeated sequences. The extent of change for the noncoding regions (about 0.093 events/bp) is less than the extent of change at the third codon positions in the rbcL-coding region (about 0.135 events/bp), including insertion/delection events. Limited sequence analysis of the analogous DNA from a wild line ( Hordeum spontaneum) and a primitive Iranian barley (H. vulgare) suggested a low rate of chloroplast DNA evolution. Compared to spinach chloroplast DNA, the barley rbcL-atpB untranslated region is extremely diverged, with only the putative rbcL promoters and ribosome-binding site being extensively conserved.