Endogenous porphyrin accumulation and photosensitization in the yeast Saccharomyces cerevisiae in the presence of 2,2 '-dipyridyl

The chelator 2,2'-dipyridyl (0.2 mM) induces a remarkable increase of proto porphyrin IX concentration as well as of its Zn-containing complex in the y east Saccharomyces cerevisiae. Endogenous porphyrin accumulation results in five- to six-fold cell sensitization to visible light (400-600 nm). Mitoch ondria isolated from the cells grown in the presence of 2,2'-dipyridyl accu mulate protoporphyrin IX and Zn-protoporphyrin IX, while plasma membranes b esides that exhibit porphyrin-type fluorescence at 670-675 nm in chloroform extract. The protoporphyrin IX content increases mon than four-fold in mit ochondria and two-fold in plasma membranes isolated from chelator-treated c ells. The relative contribution of subcellular structure photodestruction t o photoinduced cell inactivation is discussed. (C) 1999 Elsevier Science S. A. All rights reserved.