Koch T, Rüger W
Arbeitsgruppe Molekulare Genetik, Lehrstuhl Biologie der Mikroorganismen, Ruhr-Universität Bochum, Federal Republic of Germany.
Virology. 1994 Sep;203(2):294-8. doi: 10.1006/viro.1994.1487.
The Alt gene product is a component of the T4 phage head. Upon infection of the host cell, approximately 40 copies of the Alt protein enter the cell together with the viral DNA molecule. The Alt protein then ADP-ribosylates one of the two alpha-subunits of host RNA polymerase. A restriction fragment harboring the ADP-ribosyltransferase gene of bacteriophage T4 was cloned into the plasmid vector pBluescript, the nucleotide sequence was determined, and the reading frame was identified. Two M13 clone libraries, established with DNA isolated from bacteriophages T2 and T6, then were screened for the corresponding genes. The nucleotide sequences of the three alt genes and the deduced amino acid sequences were compared. Secondary structure predictions and NAD-binding studies resulted in the location of the substrate-binding site in the NH2-terminal regions of the enzymes.
Alt基因产物是T4噬菌体头部的一个组成部分。在感染宿主细胞时，大约40个Alt蛋白拷贝与病毒DNA分子一起进入细胞。然后，Alt蛋白将宿主RNA聚合酶的两个α亚基之一进行ADP核糖基化。将携带噬菌体T4的ADP核糖基转移酶基因的一个限制片段克隆到质粒载体pBluescript中，测定核苷酸序列，并确定阅读框。然后，用从噬菌体T2和T6分离的DNA建立的两个M13克隆文库筛选相应的基因。比较了三个alt基因的核苷酸序列和推导的氨基酸序列。二级结构预测和NAD结合研究确定了酶的底物结合位点在氨基末端区域。
