Engineering a new magnesium binding site in the subunit contact region of Escherichia coli inorganic pyrophosphatase

: Parfenyev AN, Salminen A, Baykov AA, Lahti R

Publisher: CONSULTANTS BUREAU

: 2000

: Биохимия / Biochemistry

: BIOCHEMISTRY-MOSCOW

: BIOCHEMISTRY-MOSCOW+

: 65

: 3

: 388

: 392

: 5

: 0006-2979

Three Gln-80 residues belonging to different subunits of homohexameric Escherichia coli pyrophosphatase are separated by only one water molecule to which they are hydrogen bonded. Substitution of Glu for Gln-80 stabilizes quaternary structure of the enzyme but has only a small effect on enzyme activity. The substitution stimulates Mg2+ binding and changes the appearance of the Mg2+ concentration dependence of the rate constant for the trimer --> hexamer transition. These data suggest that a new Mg2+ binding site is formed in the intersubunit contact region as a result of the substitution. Three-dimensional modeling of the mutated protein showed that a chelate complex might form involving two of the three Glu-80 residues.

Biochemistry, cell and molecular biology