Cloning of the gene encoding cucumber lumazine synthase and an analysis of its promoter activity in cucumber

Promoters are an important regulatory element controlling the temporal and spatial expression of genes; thus, they play a critical role in genetic engineering by controlling target gene expression. Cucumber is a widely planted vegetable with a pleasant flavor and high economic value. However, most genetic engineering studies involving cucumber have utilized the CaMV 35S promoter, which mediates ubiquitous target gene expression. To identify a promoter that is highly expressed in cucumber fruit, total proteins from cucumber fruit were analyzed by two-dimensional gel electrophoresis. One spot which is highly expressed in fruit was sequenced from its N-terminus using the Edman degradation method. A total of 10 amino acids (Ala-Val-Arg-His-Ile-Ala-Gly-Ser-Leu-Ala) were sequenced. Based on these 10 residues, a cDNA fragment 905 bp in length was cloned using 3′- and 5′-RACE. The corresponding gene, which encodes 220 amino acids, showed 65-73% similarity to other plant lumazine synthases without the signal pepti...