Adenosine triphosphatase of bean plastids: its properties and site of formation.
Extracts of bean (Phaseolus vulgaris L.) etioplasts and chloroplasts contain a dithiothreitol-activated Ca(2+)-dependent adenosine triphosphatase which is inhibited by Dio-9. The chloroplast and etioplast enzymes have identical R(F) values upon disc gel electrophoresis. Optimum extraction of the enzyme from either plastid preparation is accomplished with 1 mm ethylenediamine tetraacetic acid. Photophosphorylation capacity can be partially restored to depleted chloroplast preparations by addition of either the chloroplast or etioplast extract. These results suggest that the adenosine triphosphatase from etioplasts and chloroplasts represents a modified coupling factor for photophosphorylation.The specific activity of the adenosine triphosphatase in the extracts of plastids increases upon greening of etiolated plants due to protein synthesis. This light-induced increase is inhibited by both chloramphenicol and cycloheximide, specific inhibitors of chloroplastic and cytoplasmic protein synthesis. There is no accumulation of adenosine triphosphatase in postribosomal supernatants of cycloheximide or chloramphenicol treated leaves. The results indicate that both the chloroplastic and the cytoplasmic ribosomal systems are required for the formation of the chloroplast adenosine triphosphatase.
Horak
A
A
Department of Plant Science, The University of Manitoba, Winnipeg 19, Manitoba, Canada.
Hill
R D
RD