The membranes of all living cells contain specific transport proteins that enable the cell to accumulate nutrients and to maintain appropriate concentration gradients of ions. We will study the structure and function of a specific active transport system in order to gain some understanding of how this process occurs. The transport system that will be studied is the maltose/maltodextrin transport system of Escherichia coli. This system is composed of five protein subunits which enable the cell to actively pump maltose and longer polymers of glucose (maltodextrins) into the cytoplasm. We will use biochemical techniques to localize the sites that interact with substrate molecules. In addition we will use specific labels for locating the site(s) at which the energy donor interacts with the system. Finally we will define the location at which the water soluble maltose binding protein interacts with the membrane bound components of the system. We will also use a genetic approach to complement these biochemical experiments. We will isolate mutants with altered substrate specificity to localize the substrate recognition site genetically. In addition we will isolate mutants in which the interaction of the membrane proteins with maltose binding protein has been altered. We will determine the sites of these mutations by DNA sequencing and comparing the mutant sequence with the known wild-type sequence. Our long term goal is to generate a picture of how substrate molecules interact with the proteins during the process of translocation through the membrane and how this process is coupled to energy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI019276-04
Application #
3128627
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1982-08-01
Project End
1986-08-31
Budget Start
1985-09-30
Budget End
1986-08-31
Support Year
4
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Type
Schools of Medicine
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10027
Covitz, K M; Panagiotidis, C H; Hor, L I et al. (1994) Mutations that alter the transmembrane signalling pathway in an ATP binding cassette (ABC) transporter. EMBO J 13:1752-9
Hor, L I; Shuman, H A (1993) Genetic analysis of periplasmic binding protein dependent transport in Escherichia coli. Each lobe of maltose-binding protein interacts with a different subunit of the MalFGK2 membrane transport complex. J Mol Biol 233:659-70
Panagiotidis, C H; Reyes, M; Sievertsen, A et al. (1993) Characterization of the structural requirements for assembly and nucleotide binding of an ATP-binding cassette transporter. The maltose transport system of Escherichia coli. J Biol Chem 268:23685-96
Dean, D A; Hor, L I; Shuman, H A et al. (1992) Interaction between maltose-binding protein and the membrane-associated maltose transporter complex in Escherichia coli. Mol Microbiol 6:2033-40
Davidson, A L; Shuman, H A; Nikaido, H (1992) Mechanism of maltose transport in Escherichia coli: transmembrane signaling by periplasmic binding proteins. Proc Natl Acad Sci U S A 89:2360-4
Tapio, S; Yeh, F; Shuman, H A et al. (1991) The malZ gene of Escherichia coli, a member of the maltose regulon, encodes a maltodextrin glucosidase. J Biol Chem 266:19450-8
Kuhnau, S; Reyes, M; Sievertsen, A et al. (1991) The activities of the Escherichia coli MalK protein in maltose transport, regulation, and inducer exclusion can be separated by mutations. J Bacteriol 173:2180-6
Treptow, N A; Shuman, H A (1988) Allele-specific malE mutations that restore interactions between maltose-binding protein and the inner-membrane components of the maltose transport system. J Mol Biol 202:809-22
Shuman, H A (1987) The genetics of active transport in bacteria. Annu Rev Genet 21:155-77
Reyes, M; Treptow, N A; Shuman, H A (1986) Transport of p-nitrophenyl-alpha-maltoside by the maltose transport system of Escherichia coli and its subsequent hydrolysis by a cytoplasmic alpha-maltosidase. J Bacteriol 165:918-22

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