Yang J, Ganesan S, Sarsero J, Pittard A J
Department of Microbiology, University of Melbourne, Parkville, Victoria, Australia.
J Bacteriol. 1993 Mar;175(6):1767-76. doi: 10.1128/jb.175.6.1767-1776.1993.
The TyrR protein is involved in both repression and activation of the genes of the TyrR regulon. Correction of an error in a previously published sequence has revealed a Cro-like helix-turn-helix DNA-binding domain near the carboxyl terminus. Site-directed mutagenesis in this region has generated a number of mutants that can no longer repress or activate. Deletions of amino acid residues 5 to 42 produced a protein that could repress but not activate. The central domain of TyrR contains an ATP-binding site and is homologous with the NtrC family of activator proteins. A mutation to site A of the ATP-binding site and other mutations in this region affect tyrosine-mediated repression but do not prevent activation or phenylalanine-mediated repression of aroG.
TyrR蛋白参与TyrR调节子基因的阻遏和激活。对先前发表序列中的一个错误进行校正后,发现在羧基末端附近有一个类似Cro的螺旋-转角-螺旋DNA结合结构域。该区域的定点诱变产生了许多不再具有阻遏或激活能力的突变体。缺失氨基酸残基5至42产生了一种能够阻遏但不能激活的蛋白质。TyrR的中央结构域包含一个ATP结合位点,并且与激活蛋白的NtrC家族同源。ATP结合位点的A位点突变以及该区域的其他突变影响酪氨酸介导的阻遏,但不阻止aroG的激活或苯丙氨酸介导的阻遏。