Structural studies of two mutants of amicyanin from Paracoccus denitrificans that stabilize the reduced state of the copper

被引:32
作者
Carrell, CJ
Sun, DP
Jiang, SL
Davidson, VL
Mathews, FS [1 ]
机构
[1] Washington Univ, Sch Med, Dept Biochem & Mol Biophys, St Louis, MO 63110 USA
[2] Univ Mississippi, Sch Med, Dept Biochem, Jackson, MS 39216 USA
关键词
D O I
10.1021/bi049634z
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Mutation of Pro94 to phenylalanine or alanine significantly alters the redox properties of the type I copper center of amicyanin. Each mutation increases the redox midpoint potential (E.) value by at least 140 mV and shifts the pK(a) for the pH dependence of the E-m value to a more acidic value. Atomic resolution (0.99-1.1 Angstrom) structures of both the P94F and P94A amicyanin have been determined in the oxidized and reduced states. In each amicyanin mutant, an electron-withdrawing hydrogen bond to the copper-coordinating thiolate sulfur of Cys92 is introduced by movement of the amide nitrogens of Phe94 and Ala94 much closer to the thiolate sulfur than in wild-type amicyanin. This is the likely explanation for the much more positive E-m values which result from each of these mutations. The observed decrease in the pK(a) value for the pH dependence of the E-m value that is seen in the mutants seems to be correlated with steric hindrance to the rotation of the His95 copper ligand which results from the mutations. In wild-type amicyanin the His95 side chain undergoes a redox and pH-dependent conformational change which accounts for the pH dependence of the E-m value of amicyanin. The reduced P94A amicyanin exhibits two alternate conformations with the positions of the copper 1.4 Angstrom apart. In one of these conformations, a water molecule appears to have replaced Met98 as a copper ligand. The relevance of these structures to the electron transfer properties of P94F and P94A amicyanin are also discussed.
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页码:9372 / 9380
页数:9
相关论文
共 37 条
[1]  
ADMAN ET, 1991, ADV PROTEIN CHEM, V42, P145
[3]  
Brooks H. B., 1994, J AM CHEM SOC, V116, P11202
[4]   KINETIC AND THERMODYNAMIC ANALYSIS OF A PHYSIOLOGICAL INTERMOLECULAR ELECTRON-TRANSFER REACTION BETWEEN METHYLAMINE DEHYDROGENASE AND AMICYANIN [J].
BROOKS, HB ;
DAVIDSON, VL .
BIOCHEMISTRY, 1994, 33 (19) :5696-5701
[5]   FREE R-VALUE - A NOVEL STATISTICAL QUANTITY FOR ASSESSING THE ACCURACY OF CRYSTAL-STRUCTURES [J].
BRUNGER, AT .
NATURE, 1992, 355 (6359) :472-475
[6]  
Brunger AT, 1998, ACTA CRYSTALLOGR D, V54, P905, DOI 10.1107/s0907444998003254
[7]   Crystallographic and NMR investigation of cobalt-substituted amicyanin [J].
Carrell, CJ ;
Wang, XT ;
Jones, LM ;
Jarrett, WL ;
Davidson, VL ;
Mathews, FS .
BIOCHEMISTRY, 2004, 43 (29) :9381-9389
[8]   CRYSTAL-STRUCTURE OF AN ELECTRON-TRANSFER COMPLEX BETWEEN METHYLAMINE DEHYDROGENASE AND AMICYANIN [J].
CHEN, LY ;
DURLEY, R ;
POLIKS, BJ ;
HAMADA, K ;
CHEN, ZW ;
MATHEWS, FS ;
DAVIDSON, VL ;
SATOW, Y ;
HUIZINGA, E ;
VELLIEUX, FMD ;
HOL, WGJ .
BIOCHEMISTRY, 1992, 31 (21) :4959-4964
[9]   STRUCTURE OF AN ELECTRON-TRANSFER COMPLEX - METHYLAMINE DEHYDROGENASE, AMICYANIN, AND CYTOCHROME-C(551I) [J].
CHEN, LY ;
DURLEY, RCE ;
MATHEWS, FS ;
DAVIDSON, VL .
SCIENCE, 1994, 264 (5155) :86-90
[10]   Remarks about protein structure precision [J].
Cruickshank, DWJ .
ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY, 1999, 55 :583-601