1.Structure and mechanism of canonical ABC import systems in prokaryotes
The family of ABC ("ATP-Binding Cassette") transport systems comprises an extremely diverse class of membrane transport proteins that couple the energy of ATP hydrolysis to the translocation of solutes across biological membranes. Members of this family not only accomplish the uptake of nutrients but are involved in a large variety of processes, such as signal transduction, protein secretion, drug and antibiotic resistance, antigen presentation, bacterial pathogenesis and sporulation.
ABC transporters have been identified in organisms belonging to each of the three major kingdoms of life (bacteria, archaea and eukarya, including man), and thus might be considered as an ancient proteinaceous device for solutes to pass a lipid bilayer against a concentration gradient.
We study the structure and function of canonical (binding protein-dependent) ABC importers from various bacteria and archaea by molecular biological, biochemical and biophysical means.
Simplified model of the translocation mechanism of a binding protein-dependent
ABC transporter.
2. Acarbose metabolism in Actinomycetes
The pseudomaltotetraose acarbose (acarviosyl-1,4-maltose), produced by strains of the genera Actinoplanes and Streptomyces, is an inhibitor of various a-glucosidases, including those in the human intestine. Thus, acarbose is clinically used for the treatment of patients suffering from type II or insulin-independent diabetes. Besides inhibiting the growth of competing organisms on maltose/maltodextrins as sole sources of carbon and energy, an additional role of acarbose as a 'carbophor' (carbon storage molecule) for the uptake of carbon sources is discussed. We study the roles of ABC transporters from Actinoplanes sp. and Streptomyces glaucescens in the uptake and export of acarbose and longer homologs.
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