ATP-BINDING-CASSETTE (ABC) TRANSPORT-SYSTEMS - FUNCTIONAL AND STRUCTURAL ASPECTS OF THE ATP-HYDROLYZING SUBUNITS DOMAINS/

Members of the superfamily of adenosine triphosphate (ATP)-binding-cas sette (ABC) transport systems couple the hydrolysis of ATP to the tran slocation of solutes across a biological membrane. Recognized by their common modular organization and two sequence motifs that constitute a nucleotide binding fold, ABC transporters are widespread among all li ving organisms. They accomplish not only the uptake of nutrients in ba cteria but are involved in diverse processes, such as signal transduct ion, protein secretion, drug and antibiotic resistance, antigen presen tation, bacterial pathogenesis and sporulation. Moreover, some human i nheritable diseases, like cystic fibrosis, adrenoleukodystrophy and St argardt's disease are caused by defective ABC transport systems. Thus, albeit of major significance, details of the molecular mechanism by w hich these systems exert their functions are still poorly understood. In this review, recent data concerning the properties and putative rol e of the ATP-hydrolyzing subunits/domains are summarized and compared between bacterial and eukaryotic systems. (C) 1998 Federation of Europ ean Microbiological Societies. Published by Elsevier Science B.V.