Porphyrin biosynthesis in Rhodopseudomonas palustris-XII. δ-aminolevulinate synthetase switch-off/on regulation

• Autores: Viale, A.A.; Wider, E.A.; Del C. Batlle, A.M.
• Año de publicación: 1987
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Int. J. Biochem. 1987;19(4):379-383
• Materia: 5 aminolevulinate synthase; bacteriochlorophyll; chloramphenicol; porphyrin; adaptation; article; biosynthesis; enzymology; homeostasis; metabolism; oxidation reduction reaction; Rhodopseudomonas; 5-Aminolevulinate Synthetase; Adaptation, Physiological; Bacteriochlorophylls; Chloramphenicol; Homeostasis; Oxidation-Reduction; Porphyrins; Rhodopseudomonas; Support, Non-U.S. Gov't
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

The high levels of δ-aminolevulinate synthetase (ALA-S) in Rhodopseudomonas palustris cells grown anaerobically in the light (Ph) decrease to those found in cells grown aerobically in the dark (A), when the former cultures were vigorously oxygenated; simultaneously bacteriochlorophyll (Bchl) synthesis abruptly halted leading to diminished steady-state specific Bchl content. When flushing oxygen was interrupted, enzymic activity increased, whether chloramphenicol was present or not in the medium; if the protein synthesis inhibitor was added when oxygenation started, ALA-S declined in the same fashion as in its absence, but thereafter reactivation of the enzyme was lower than before. Succinyl-CoA-synthetase and ALA-dehydratase activities were also measured under the conditions described, and no changes at all have been observed. The existence of different forms of ALA-S in R. palustris depending on growth conditions is postulated along with the formation of low molecular weight factors which can modulate ALA-S activity by binding to the enzyme; a widespread mechanism in the adaptation of micro-organisms to changes in environment. It is also proposed that this particular regulatory phenomenon, could be referred to as a switch off/on mechanism controlling ALA-S activity in R. palustris. © 1987.
Fil:Viale, A.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Del C. Batlle, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.