ATP as Effector of Inorganic Pyrophosphatase of Escherichia coli. The Role of Residue Lys112 in Binding Effectors

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E. V. Rodina^1,2*, N. N. Vorobyeva¹, S. A. Kurilova², T. S. Sitnik², and T. I. Nazarova²

¹Chemical Faculty, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-3181; E-mail: rodina@belozersky.msu.ru

²Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-3181; E-mail: nazarova@belozersky.msu.ru

^* To whom correspondence should be addressed.

Received August 1, 2006; Revision received September 6, 2006

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It has been shown that PP_i, methylenediphosphonate, and ATP act as effectors of Escherichia coli inorganic pyrophosphatase (E-PPase), and that they compete for binding at the allosteric regulatory site. On the basis of chemical modification and computer modeling of a structure of the enzyme-ATP complex, a number of amino acid residues presumably involved in binding effectors has been revealed. Mutant variants Lys112Gln, Lys112Gln/Lys148Gln, and Lys112Gln/Lys115Ala of E-PPase have been obtained, as well as a modified variant of wild type E-PPase (^Adwt PPase) with a derivative of ATP chemically attached to the amino group of Lys146. Kinetic properties of these variants have been investigated and compared to the earlier described variants Lys115Ala, Arg43Gln, and Lys148Gln. Analysis of the data confirms the proposed location of an effector binding site in a cluster of positively charged amino acid residues including the side chains of Arg43, Lys146 (subunit A), Lys112, and Lys115 (subunit B). Lys112 is supposed to play a key role in forming contacts with the phosphate groups of the three studied effectors.

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KEY WORDS: pyrophosphatase, ATP, PP_i, binding site, effector, site-directed mutagenesis

DOI: 10.1134/S0006297907010129

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