Type II cytochrome c(3) from desulfovibrio africanus: a structure-function correlation

Pereira, Patricia M., Catarino, Teresa, Turner, David L., Xavier, Antonio V. and Louro, Ricardo O. (2001) Type II cytochrome c(3) from desulfovibrio africanus: a structure-function correlation. Journal of Inorganic Biochemistry, 86 (1), 376. (doi:10.1016/S0162-0134(01)00284-7).

Abstract

A type II tetrahaem cytochrome c3 (TplI-c3) was isolated from the periplasmic space of Desulfovibrio africanus, a sulfate-reducing bacter'm m~. Although structurally si.milar to the .well charact.ensed type I. cytochrome s c3 (TpI-c3), this protein displays distinct properties z-5. In particular, it is part of a polycistronic operon coding for transmembrane redox proteins 4, suggesting a different physiological function from that performed by TpI-c3. The thermodynamic parameters of the haems and of an acid-base centre in the TplI-c3 were determined by using the NMR and visible spectroscopies and by fitting the data to a five centres thermodynamic model 6. The thermodynamic features are correlated with the redox-linked structural differences reported in the literature3: positive cooperativity between the haems is not observed. The redox-Bohr effect is strongly associated with haem II instead of haem I as in the case for all of the TpI-c3s 5' 6. These novel functional properties are in agreement with the structural differences between TpI- and TplI-c3 and the redox-linked structural changes observed and may be relevant for the difference in the physiological function proposed for TpII-c3s vs TpI-c3s TM

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