Richardson I B, Katz M E, Hynes M J
Department of Genetics, University of Melbourne, Parkville, Victoria, Australia.
Mol Cell Biol. 1992 Jan;12(1):337-46. doi: 10.1128/mcb.12.1.337-346.1992.
The lam locus of Aspergillus nidulans consists of two divergently transcribed genes, lamA and lamB, involved in the utilization of lactams such as 2-pyrrolidinone. Both genes are under the control of the positive regulatory gene amdR and are subject to carbon and nitrogen metabolite repression. The lamB gene and the region between the two genes have been sequenced, and the start points of transcription have been determined. Within the lam locus are two sequences with homology to elements, required for AmdR regulation, found in the 5' regions of the coregulated genes amdS and gatA. In vitro and in vivo assays were used to investigate the lam and gatA regulatory elements. One of the three gatA elements and one of the two lam elements were shown to bind AmdR protein in vivo and activate transcription. With a gel shift mobility assay, in vitro binding of AmdR protein to the functional gatA element was detected. Both the functional gatA and lam boxes contain within them a CAAT sequence. In vitro binding analysis indicates that a CCAAT-specific factor(s) binds at these sequences, adjacent to or overlapping the AmdR protein-binding site.
构巢曲霉的lam基因座由两个反向转录的基因lamA和lamB组成，它们参与内酰胺类物质（如2-吡咯烷酮）的利用。这两个基因都受正向调节基因amdR的控制，并受到碳和氮代谢物阻遏的影响。lamB基因以及这两个基因之间的区域已被测序，转录起始点也已确定。在lam基因座内有两个与在共调节基因amdS和gatA的5'区域中发现的、AmdR调节所需元件具有同源性的序列。采用体外和体内试验来研究lam和gatA调节元件。三个gatA元件中的一个和两个lam元件中的一个在体内显示能结合AmdR蛋白并激活转录。通过凝胶迁移率变动分析，检测到AmdR蛋白在体外与功能性gatA元件的结合。功能性gatA盒和lam盒内均含有一个CAAT序列。体外结合分析表明，一种CCAAT特异性因子在这些与AmdR蛋白结合位点相邻或重叠的序列处结合。
