Kossmann J, Visser R G, Müller-Röber B, Willmitzer L, Sonnewald U
Institut für Genbiologische Forschung, Berlin GmbH, Berlin, FRG.
Mol Gen Genet. 1991 Nov;230(1-2):39-44. doi: 10.1007/BF00290648.
One of the key enzymes involved in the formation of amylopectin, which is the major component of starch, is branching enzyme. A cDNA for potato branching enzyme was cloned by screening a tuber-specific cDNA expression library using an antiserum directed against a denatured preparation of the protein. Complementation of an Escherichia coli strain deficient in branching enzyme was achieved using a construct derived from this clone. Analysis of the expression of the gene in potato revealed a close association with conditions favouring starch biosynthesis. The expression pattern of the gene coding for potato branching enzyme, as analyzed at the mRNA level, closely resembles that of AGPase S, a gene coding for one of the subunits of ADP-glucose pyrophosphorylase, which is the key regulatory enzyme in the starch biosynthetic pathway. This raises the possibility that enzymes involved in the pathway are coordinately regulated at the transcriptional level.
支链淀粉酶是参与支链淀粉形成的关键酶之一，而支链淀粉是淀粉的主要成分。通过用针对该蛋白质变性制剂的抗血清筛选块茎特异性cDNA表达文库，克隆了马铃薯支链淀粉酶的cDNA。使用源自该克隆的构建体实现了对缺乏支链淀粉酶的大肠杆菌菌株的互补。对该基因在马铃薯中的表达分析表明，其与有利于淀粉生物合成的条件密切相关。在mRNA水平分析时，编码马铃薯支链淀粉酶的基因的表达模式与AGPase S非常相似，AGPase S是编码ADP-葡萄糖焦磷酸化酶亚基之一的基因，而ADP-葡萄糖焦磷酸化酶是淀粉生物合成途径中的关键调节酶。这增加了该途径中涉及的酶在转录水平上受到协调调节的可能性。
