Regulation of Alternative Nitrogenase Systems by Environmental Factors in the Cyanobacterium Anabaena variabilis

摘要: Anabaena variabilis ATCC 29413 is a filamentous cyanobacterium that fixes dinitrogen under variety of environmental conditions. Under aerobic conditions, nitrogen fixation occurs exclusively in specialized cells called heterocysts. Heterocysts are differentiated develop pattern from vegetative the filament response to limitation fixed (reviewed, 11). The primary Mo-dependent nitrogenase this organism encoded by contiguous cluster nifl genes transcribed only heterocysts (1, 9). These very similar nif sp. strain PCC 7120 3), which also (2). We have recently characterized alternative gene clusters absent 7120. One system, vnf, encodes vanadium-dependent functions (7); whereas other nif2, Mo-nitrogenase strictly anaerobic conditions and (9). describe here regulation these systems, respond changes factors.