McGurl B, Ryan C A
Institute of Biological Chemistry, Washington State University, Pullman 99164-6340.
Plant Mol Biol. 1992 Nov;20(3):405-9. doi: 10.1007/BF00040600.
The organization of the gene encoding tomato prosystemin, a 200 amino acid protein precursor of the 18 amino acid polypeptide inducer of proteinase inhibitor synthesis in tomato and potato plants, is reported. The prosystemin sequence reveals that the gene, which is composed of five homologous pairs of exons plus a non-homologous exon at the C-terminus containing the systemin sequence, has evolved by several gene duplication-elongation events from a much smaller ancestral gene. The nucleotide and amino acid sequence homologies among the exons suggest that a small ancestral gene was duplicated to form at least two tandem repeats, followed by subsequent duplication-elongation events that resulted in five tandemly repeated nucleotide sequences and three duplicated amino acid sequence elements. Since the systemin nucleotide or amino acid sequence was not duplicated, it was either not part of the gene duplication-elongation events or its coding region evolved separately and may even have been added to the tandemly repeated part of the gene at a later time.
本文报道了番茄前系统素基因的组织情况，前系统素是番茄和马铃薯植株中蛋白酶抑制剂合成的18个氨基酸多肽诱导物的200个氨基酸蛋白质前体。前系统素序列显示，该基因由五对同源外显子加上C端一个包含系统素序列的非同源外显子组成，它是通过几次基因复制-延伸事件从一个小得多的祖先基因进化而来的。外显子之间的核苷酸和氨基酸序列同源性表明，一个小的祖先基因被复制形成至少两个串联重复序列，随后发生的复制-延伸事件导致了五个串联重复的核苷酸序列和三个重复的氨基酸序列元件。由于系统素核苷酸或氨基酸序列没有被复制，它要么不是基因复制-延伸事件的一部分，要么其编码区域是独立进化的，甚至可能是在后来添加到基因的串联重复部分的。
