Single mutation at the intersubunit interface confers extra efficiency to Cu,Zn superoxide dismutase.
The Val28-->Gly single mutant at the subunit interface of Cu,Zn superoxide dismutase from Photobacterium leiognathi displays a k(cat)/K(M) value of 1.7x10(10) M(-1) s(-1), twice that of the native enzyme. Analysis of the three-dimensional structure indicates that the active site Cu,Zn center is not perturbed, slight structural deviations being only localized in proximity of the mutation site. The enzyme-substrate association rate, calculated by Brownian dynamics simulation, is identical for both enzymes, indicating that the higher catalytic efficiency of the Val28-->Gly mutant is not due to a more favorable electrostatic potential distribution. This result demonstrates the occurrence of an intramolecular communication between the mutation site and the catalytic center, about 18 A away and indicates a new strategy to encode extra efficiency within other members of this enzymatic family.
Stroppolo
M E
ME
INFM, Dipartimento di Biologie, Universita di Roma, Tor Vergata, Via della Ricerca Scientifica snc, 00133 Rome, Italy.
Pesce
A
A
Falconi
M
M
O'Neill
P
P
Bolognesi
M
M
Desideri
A
A
D019943:Amino Acid Substitution; D001665:Binding Sites; D005818:Genetic Engineering; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D010776:Photobacterium / Q000201:enzymology; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D013379:Substrate Specificity; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D021122:Protein Subunits; D013482:Superoxide Dismutase