Characterization and purification of a membrane‐bound archaebacterial pyrophosphatase from Sulfolobus acidocaldarius

Abstract

Plasma membranes of thermoacidophilic archaebacterium Sulfolobus acidocaldarius (DSM 639) display a pyrophosphate‐hydrolyzing activity [M. Lübben & G. Schäfer (1987) Eur. J. Biochem. 164, 533–540]. In our present work, we solubilized and purified this pyrophosphatase to homogeneity. It consists of single subunit with a molecular mass of 17 – 18 kDa, forming an oligomer of 70 kDa under native conditions. Edman degradation revealed 30 amino acids of the N‐terminus. The enzyme cleaves phosphoric‐acid‐anhydride bonds independently of monovalent or divalent cations. Temperature and pH optima of 75°C and 3.5–3.7, respectively, characterize it as an ectoenzyime. Membrane lipids of Sulfolobus stimulate the activity. The dolichol‐pyrophosphate‐complexing peptide‐antibiotic bacitracin inhibited growth of Sulfolobus. A possible function of the acid pyrophosphatase is the hydrolysis of dolichol pyrophosphate in connection with glycosylation reactions of membrane proteins. Copyright © 1992, Wiley Blackwell. All rights reserved