Co-Authors:
Belkin, S., Division of Microbial and Molecular Ecology, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
Siderer, Y., Division of Microbial and Molecular Ecology, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
Shahak, Y., Biochemistry Department, Weizmann Institute of Science, Rehovot, 76100, Israel
Arieli, B., Division of Microbial and Molecular Ecology, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
Padan, E., Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
Abstract:
The effect of 2,3-dimercaptopropan-1-ol (BAL) on photosynthetic electron transport was studied in Oscillatoria limnetica cells as well as in spinach chloroplasts. Preincubation of the cyanobacterial cells with BAL under aerobic conditions caused inhibition of the sulfide-dependent H2 evolution. The inhibited site was bypassed by N,N,N′,N′-tetramethyl-p-phenylene diamine. Similarly, NADP photoreduction by spinach chloroplasts was inhibited by BAL pretreatment and restored by the addition of reduced 2,6-dichlorophenol-indophenol. These results accord previous data demonstrating damage of mitochondrial Rieske iron-sulfur protein after BAL treatment (Slater, E.C. and De Vries, S. (1980) Nature 288, 717-718). However, in chloroplasts there was no change in the Rieske center ESR spectrum after BAL treatment. When added anaerobically, BAL served as an electron donor for light-dependent, H2 evolution in cyanobacteria or for NADP reduction in spinach chloroplasts. These reactions were insensitive to 3-(3′,4′-dichlorophenyl)-1,1dimethylurea (DCMU), but sensitive to 2,5-dibromothymoquinone or to aerobic pretreatment with BAL. The Rieske protein ESR signal of chloroplasts (g = 1.89) which disappeared upon illumination in the presence of DCMU and methyl viologen, was restored by BAL. It is suggested that as opposed to its aerobic inhibitory effect, BAL donates electrons to the Rieske protein under anaerobic conditions. © 1984.