TY - JOUR
T1 - Electron Transfer Complexes of Cytochrome c Peroxidase from Paracoccus denitrificans Containing more than One Cytochrome
AU - Pettigrew, Graham W.
AU - Pauleta, Sofia R.
AU - Goodhew, Celia F.
AU - Cooper, Alan
AU - Nutley, Margaret
AU - Jumel, Kornelia
AU - Harding, Stephen E.
AU - Costa, Cristina
AU - Krippahl, Ludwig
AU - Moura, Isabel
AU - Moura, José J. G.
PY - 2003/10/21
Y1 - 2003/10/21
N2 - According to the model proposed in previous papers [Pettigrew, G. W., Prazeres, S., Costa, C., Palma, N., Krippahl, L., and Moura, J. J. (1999) The structure of an electron-transfer complex containing a cytochrome c and a peroxidase, J. Biol. Chem. 274, 11383-11389; Pettigrew, G. W., Goodhew, C. F., Cooper, A., Nutley, M., Jumel, K., and Harding, S. E. (2003) Electron transfer complexes of cytochrome c peroxidase from Paracoccus denitrificans, Biochemistry 42, 2046-2055], cytochrome c peroxidase of Paracoccus denitrificans can accommodate horse cytochrome c and Paracoccus cytochrome c550 at different sites on its molecular surface. Here we use 1H NMR spectroscopy, analytical ultracentrifugation, molecular docking simulation, and microcalorimetry to investigate whether these small cytochromes can be accommodated simultaneously in the formation of a ternary complex. The pattern of perturbation of heme methyl and methionine methyl resonances in binary and ternary solutions shows that a ternary complex can be formed, and this is confirmed by the increase in the sedimentation coefficient upon addition of horse cytochrome c to a solution in which cytochrome c 550 fully occupies its binding site on cytochrome c peroxidase. Docking experiments in which favored binary solutions of cytochrome c 550 bound to cytochrome c peroxidase act as targets for horse cytochrome c and the reciprocal experiments in which favored binary solutions of horse cytochrome c bound to cytochrome c peroxidase act as targets for cytochrome c550 show that the enzyme can accommodate both cytochromes at the same time on adjacent sites. Microcalorimetric titrations are difficult to interpret but are consistent with a weakened binding of horse cytochrome c550 to a binary complex of cytochrome c peroxidase and cytochrome c550 and binding of cytochrome c550 to the cytochrome c peroxidase that is affected little by the presence of horse cytochrome c in the other site. The presence of a substantial capture surface for small cytochromes on the cytochrome c peroxidase has implications for rate enhancement mechanisms which ensure that the two electrons required for re-reduction of the enzyme after reaction with hydrogen peroxide are delivered efficiently.
AB - According to the model proposed in previous papers [Pettigrew, G. W., Prazeres, S., Costa, C., Palma, N., Krippahl, L., and Moura, J. J. (1999) The structure of an electron-transfer complex containing a cytochrome c and a peroxidase, J. Biol. Chem. 274, 11383-11389; Pettigrew, G. W., Goodhew, C. F., Cooper, A., Nutley, M., Jumel, K., and Harding, S. E. (2003) Electron transfer complexes of cytochrome c peroxidase from Paracoccus denitrificans, Biochemistry 42, 2046-2055], cytochrome c peroxidase of Paracoccus denitrificans can accommodate horse cytochrome c and Paracoccus cytochrome c550 at different sites on its molecular surface. Here we use 1H NMR spectroscopy, analytical ultracentrifugation, molecular docking simulation, and microcalorimetry to investigate whether these small cytochromes can be accommodated simultaneously in the formation of a ternary complex. The pattern of perturbation of heme methyl and methionine methyl resonances in binary and ternary solutions shows that a ternary complex can be formed, and this is confirmed by the increase in the sedimentation coefficient upon addition of horse cytochrome c to a solution in which cytochrome c 550 fully occupies its binding site on cytochrome c peroxidase. Docking experiments in which favored binary solutions of cytochrome c 550 bound to cytochrome c peroxidase act as targets for horse cytochrome c and the reciprocal experiments in which favored binary solutions of horse cytochrome c bound to cytochrome c peroxidase act as targets for cytochrome c550 show that the enzyme can accommodate both cytochromes at the same time on adjacent sites. Microcalorimetric titrations are difficult to interpret but are consistent with a weakened binding of horse cytochrome c550 to a binary complex of cytochrome c peroxidase and cytochrome c550 and binding of cytochrome c550 to the cytochrome c peroxidase that is affected little by the presence of horse cytochrome c in the other site. The presence of a substantial capture surface for small cytochromes on the cytochrome c peroxidase has implications for rate enhancement mechanisms which ensure that the two electrons required for re-reduction of the enzyme after reaction with hydrogen peroxide are delivered efficiently.
UR - http://www.scopus.com/inward/record.url?scp=10744222048&partnerID=8YFLogxK
U2 - 10.1021/bi034829c
DO - 10.1021/bi034829c
M3 - Article
C2 - 14556628
AN - SCOPUS:10744222048
VL - 42
SP - 11968
EP - 11981
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 41
ER -