Yoshida N, Hayashi K, Nakamura K
Laboratory of Biochemistry, School of Agriculture, Nagoya University, Japan.
Gene. 1992 Oct 21;120(2):255-9. doi: 10.1016/0378-1119(92)90101-t.
A nuclear AmyB gene from sweet potato encoding beta-amylase (beta Amy) that is abundant in tuberous roots and inducible in other organs by an exogenous supply of sucrose or polygalacturonic acid, was isolated and characterized. Genomic Southern blot hybridization, restriction maps of independently isolated phage lambda genomic clones, and the nucleotide sequence of AmyB compared with that of the cDNA, all suggested that beta Amy of sweet potato is encoded by a gene that is present in a single copy per haploid genome. In the sequence of AmyB, the sequence that is identical to that of the cDNA was split into seven exons by six introns, and the transcription of this gene starts from multiple sites 26 to 30 bp downstream from a potential TATA-box sequence, 5'-TATATAA. In the 5'-upstream region of AmyB, there are sequences homologous to those conserved in the 5'-upstream regions of genes encoding sporamin, which are regulated similarly to AmyB. The 5'-upstream region of AmyB also contains sequences to which several previously known plant nuclear factors bind.
从甘薯中分离并鉴定了一个编码β-淀粉酶（βAmy）的核AmyB基因，该酶在块根中含量丰富，并且在其他器官中可通过外源供应蔗糖或聚半乳糖醛酸诱导产生。基因组Southern印迹杂交、独立分离的λ噬菌体基因组克隆的限制性图谱，以及AmyB的核苷酸序列与cDNA序列的比较，均表明甘薯的βAmy由单倍体基因组中单个拷贝存在的基因编码。在AmyB序列中，与cDNA相同的序列被6个内含子分隔成7个外显子，该基因的转录起始于潜在TATA盒序列5'-TATATAA下游26至30 bp的多个位点。在AmyB的5'-上游区域，存在与编码sporamin的基因5'-上游区域中保守序列同源的序列，这些基因与AmyB受到相似的调控。AmyB的5'-上游区域还包含几个先前已知的植物核因子结合的序列。
