Katz M E, Hynes M J
Department of Genetics, University of Melbourne, Parkville, Victoria, Australia.
Mol Cell Biol. 1989 Dec;9(12):5696-701. doi: 10.1128/mcb.9.12.5696-5701.1989.
The facB gene of Aspergillus nidulans is thought to be involved in acetate induction of enzymes required for acetate utilization and of the acetamidase encoded by the multiply regulated amdS gene. In addition, some evidence suggests that the facB gene has a structural as well as a regulatory role in acetate metabolism. The facB gene was cloned from a cosmid library by complementation of the facB101 loss-of-function mutation. Transformants receiving multiple copies of facB displayed stronger growth on acetamide media, indicating increased amdS expression, while growth on acetate was inhibited in these multicopy transformants. A 3.1-kilobase acetate-inducible facB transcript was detected by Northern (RNA) blot analysis. Examination of message levels in wild-type and mutant strains indicated that the facB gene is subject to carbon catabolite repression. Previous work has indicated that the presence of multiple copies of the 5' end of the amdS gene can result in titration of regulatory proteins. Additional copies of the facB gene were shown to specifically overcome the effect of facB product titration.
构巢曲霉的facB基因被认为参与了乙酸盐对乙酸盐利用所需酶以及由多重调控的amdS基因编码的乙酰胺酶的诱导过程。此外，一些证据表明，facB基因在乙酸盐代谢中具有结构和调节双重作用。通过对facB101功能缺失突变的互补作用，从黏粒文库中克隆出了facB基因。接受多个facB拷贝的转化体在乙酰胺培养基上生长更强，表明amdS表达增加，而在这些多拷贝转化体中，乙酸盐上的生长受到抑制。通过Northern（RNA）印迹分析检测到一个3.1千碱基的乙酸盐诱导型facB转录本。对野生型和突变株中信息水平的检测表明，facB基因受到碳分解代谢物阻遏作用的调控。先前的研究表明，amdS基因5'端的多个拷贝的存在可导致调节蛋白的滴定。已证明facB基因的额外拷贝可特异性克服facB产物滴定的影响。
