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Gene Review

malF  -  maltose transporter membrane protein

Escherichia coli O157:H7 str. Sakai

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Disease relevance of ECs5016

  • We mutagenized the EAA regions of MalF and MalG proteins of the Escherichia coli maltose transport system [1].
  • A putative helical domain in the MalK subunit of the ATP-binding-cassette transport system for maltose of Salmonella typhimurium (MalFGK2) is crucial for interaction with MalF and MalG. A study using the LacK protein of Agrobacterium radiobacter as a tool [2].
  • Introduction of the putatively non-dimerizing first TM from E. coli MalF into the lambda-TM fusion vector resulted in no immunity to lambda cI phages [3].

High impact information on ECs5016

  • Substitutions at the same positions in MalF and MalG have different phenotypes, indicating that EAA regions do not act symmetrically [1].
  • We have used genetic methods to investigate the role of the different domains of a bacterial cytoplasmic membrane protein, MalF, in determining its topology [4].
  • These results also suggest that ATP hydrolysis is not directly coupled to ligand transport even in wild-type cells and that one important function of MBP is to transmit a transmembrane signal, through the membrane-spanning MalF and MalG proteins, to the MalK protein on the other side of the membrane, so that ATP hydrolysis can occur [5].
  • Ligand translocation and ATP hydrolysis are dependent on a signaling mechanism originating from the binding protein and traveling through MalF/MalG [6].
  • We have investigated the proximity of residues in a conserved sequence ("EAA" loop) of MalF and MalG to residues in a helical segment of the MalK subunits by means of site-directed chemical cross-linking [6].

Biological context of ECs5016


Anatomical context of ECs5016

  • The proteins of this system are LamB in the outer membrane, maltose-binding protein (MBP) in the periplasm, and the proteins of the inner membrane complex (MalFGK2), composed of one MalF, one MalG, and two MalK subunits [12].

Associations of ECs5016 with chemical compounds

  • We have found a sequence which is highly conserved between MalG and MalF, the other integral inner membrane protein of the maltose transport system [13].
  • In contrast to an earlier study (McGovern, K., and Beckwith, J. (1991) J. Biol. Chem. 266, 20870-20876), the membrane insertion of MalF also is inhibited by treatment of cells with sodium azide, a potent inhibitor of SecA [14].
  • In its closed form, the NH2-terminal and COOH-terminal domains of maltose-binding protein (MBP) are proposed to be aligned to allow residues in both domains to interact simultaneously with complementary sites on the MalF and MalG proteins of the maltodextrin uptake system or with the Tar chemotactic signal transducer [15].

Analytical, diagnostic and therapeutic context of ECs5016

  • In all experiments, the MalF, MalG, and MalK proteins behaved as a multiprotein complex; all three proteins were immunoprecipitated using antibody prepared against MalF, and they copurified, eluting from a gel filtration column between markers of Mr 160,000 and 200,000 [16].


  1. Subunit interactions in ABC transporters: a conserved sequence in hydrophobic membrane proteins of periplasmic permeases defines an important site of interaction with the ATPase subunits. Mourez, M., Hofnung, M., Dassa, E. EMBO J. (1997) [Pubmed]
  2. A putative helical domain in the MalK subunit of the ATP-binding-cassette transport system for maltose of Salmonella typhimurium (MalFGK2) is crucial for interaction with MalF and MalG. A study using the LacK protein of Agrobacterium radiobacter as a tool. Wilken, S., Schmees, G., Schneider, E. Mol. Microbiol. (1996) [Pubmed]
  3. Lambda repressor N-terminal DNA-binding domain as an assay for protein transmembrane segment interactions in vivo. Leeds, J.A., Beckwith, J. J. Mol. Biol. (1998) [Pubmed]
  4. Decoding signals for membrane protein assembly using alkaline phosphatase fusions. McGovern, K., Ehrmann, M., Beckwith, J. EMBO J. (1991) [Pubmed]
  5. Mechanism of maltose transport in Escherichia coli: transmembrane signaling by periplasmic binding proteins. Davidson, A.L., Shuman, H.A., Nikaido, H. Proc. Natl. Acad. Sci. U.S.A. (1992) [Pubmed]
  6. ATP modulates subunit-subunit interactions in an ATP-binding cassette transporter (MalFGK2) determined by site-directed chemical cross-linking. Hunke, S., Mourez, M., Jehanno, M., Dassa, E., Schneider, E. J. Biol. Chem. (2000) [Pubmed]
  7. Truncation of MalF results in lactose transport via the maltose transport system of Escherichia coli. Merino, G., Shuman, H.A. J. Biol. Chem. (1998) [Pubmed]
  8. The nucleotide sequence of the gene for malF protein, an inner membrane component of the maltose transport system of Escherichia coli. Repeated DNA sequences are found in the malE-malF intercistronic region. Froshauer, S., Beckwith, J. J. Biol. Chem. (1984) [Pubmed]
  9. The protein translocation apparatus contributes to determining the topology of an integral membrane protein in Escherichia coli. Prinz, W.A., Boyd, D.H., Ehrmann, M., Beckwith, J. J. Biol. Chem. (1998) [Pubmed]
  10. Interaction between maltose-binding protein and the membrane-associated maltose transporter complex in Escherichia coli. Dean, D.A., Hor, L.I., Shuman, H.A., Nikaido, H. Mol. Microbiol. (1992) [Pubmed]
  11. Genetic approach to the role of tryptophan residues in the activities and fluorescence of a bacterial periplasmic maltose-binding protein. Martineau, P., Szmelcman, S., Spurlino, J.C., Quiocho, F.A., Hofnung, M. J. Mol. Biol. (1990) [Pubmed]
  12. Unliganded maltose-binding protein triggers lactose transport in an Escherichia coli mutant with an alteration in the maltose transport system. Merino, G., Shuman, H.A. J. Bacteriol. (1997) [Pubmed]
  13. Sequence of gene malG in E. coli K12: homologies between integral membrane components from binding protein-dependent transport systems. Dassa, E., Hofnung, M. EMBO J. (1985) [Pubmed]
  14. Insertion of the polytopic membrane protein MalF is dependent on the bacterial secretion machinery. Traxler, B., Murphy, C. J. Biol. Chem. (1996) [Pubmed]
  15. Maltose-binding protein containing an interdomain disulfide bridge confers a dominant-negative phenotype for transport and chemotaxis. Zhang, Y., Mannering, D.E., Davidson, A.L., Yao, N., Manson, M.D. J. Biol. Chem. (1996) [Pubmed]
  16. Purification and characterization of the membrane-associated components of the maltose transport system from Escherichia coli. Davidson, A.L., Nikaido, H. J. Biol. Chem. (1991) [Pubmed]
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