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Science 22 March 1991:
Vol. 251. no. 5000, pp. 1479 - 1481
DOI: 10.1126/science.1900953
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Articles

Science, Vol 251, Issue 5000, 1479-1481
Copyright © 1991 by American Association for the Advancement of Science

articles

A nonconservative serine to cysteine mutation in the sulfate-binding protein, a transport receptor

JJ He and FA Quiocho

Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030.

Serine 130 is one of seven residues that form a total of seven hydrogen bonds with the sulfate completely sequestered deep in the cleft between the two lobes of the bilobate sulfate-binding protein from Salmonella typhimurium. This residue has been replaced with Cys, Ala, and Gly by site-directed mutagenesis in an Escherichia coli expression system. Replacement with the isosteric Cys caused a 3200-fold decrease in the sulfate-binding activity relative to the wild-type activity, whereas replacement with Ala and Gly resulted in only 100- and 15-fold decreases, respectively. The effect of the Cys substitution is attributed largely to steric effect, whereas the Gly substitution more nearly reflects the loss of one hydrogen bond to the bound sulfate with a strength of only 1.6 kilocalories per mole.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
A Conserved Glutamate Is Responsible for Ion Selectivity and pH Dependence of the Mammalian Anion Exchangers AE1 and AE2.
I. Sekler, R. S. Lo, and R. R. Kopito (1995)
J. Biol. Chem. 270, 28751-28758
   Abstract »    Full Text »    PDF »
Chimeric Flavonol Sulfotransferases Define a Domain Responsible for Substrate and Position Specificities.
L. Varin, F.édér. Marsolais, and N. Brisson (1995)
J. Biol. Chem. 270, 12498-12502
   Abstract »    Full Text »    PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)