期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：10
页码：6038-6042
DOI：10.1073/pnas.78.10.6038
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The hisJ and argT genes of Salmonella typhimurium encode two periplasmic binding proteins, J and LAO, which are involved in histidine and arginine transport, respectively, and which interact with a common membrane-bound component, the P protein. The complete nucleotide sequences of these two genes have been determined. The two genes show extensive homology (70%) and presumably arose by tandem duplication of a single ancestral gene. The two encoded proteins now perform distinct functions but still retain sufficient homology to permit interaction with the same site on the membrane-bound P protein. Three lines of evidence have allowed both the amino acid-binding site and the site involved in the interaction with the P protein to be assigned to specific regions of each binding protein: (i) the distribution of amino acid differences between the two proteins; (ii) the properties of a functional chimeric protein, produced by a deletion mutant in which the first half of the argT gene is fused to the second half of the hisJ gene; (iii) the sequence change in a mutant J protein unable to interact with P.
