Coupling factors ATPases from photosynthetic bacteria.

Abstract

Considerable information on the mechanism of ATP synthesis in energy transducing membranes has been obtained by studies concerning the detachment of the membrane bound ATPase and its reconstitution from purified membrane components. Although the first successful utilization of such an approach was described for the respiratory system of an aerobic bacterium [1], the most extensive efforts in this field have been subsequently spent on respiratory and photosynthetic organelles from eukaryotic cells (for recent reviews, see [2, 3]. Only recently bacterial ATPases [4-8] have again gained the interests of biochemists mainly because of their possible involvement in bacterial active transport. Among prokaryotic photosynthetic organisms the resolution and reconstitution of the ATP synthesizing system has been achieved only for three genera of photosynthetic bacteria, namely, two members of the family Rhodospirillaceae (Rhodopseudomonas capsulata [9] and Rhodospirillum rubrum [10] and one of Chromatiaceae (Chromatium vinosum, strain D [ 11] ). Only for the first two species, however, have methods for purification and a first characterization of the protein been reported [12, 13]. This review is concerned specifically with studies on the ATPase of these three organisms; comparative considerations have been included relative to other ATPases, mitochondrial, plastidial, and bacterial, for which the reader must refer to specific review articles (e.g., [2, 3, 5]). Emphasis has been placed on the modulation of ATPase activity in intact or reconstituted membranes since these newer aspects in the study of