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

• The mutation responsible for the altered substrate specificity results in an amber stop codon at position 99 of MalF [7].
• From the predicted amino acid sequence, MalF protein contains 514 amino acids and has a molecular weight of 56,947 [8].
• We used alkaline phosphatase fusions to the membrane protein MalF to investigate the role of the protein translocation machinery in the arrangement of proteins in the cytoplasmic membrane of Escherichia coli [9].
• Active transport of maltose in Escherichia coli requires the presence of both maltose-binding protein (MBP) in the periplasm and a complex of MalF, MalG, and MalK proteins (FGK2) located in the cytoplasmic membrane [10].
• In addition, our results show that they play no role in the interactions with the other proteins of the maltose transport (MalF, MalG or MalK) or chemotaxis (Tar) systems.(ABSTRACT TRUNCATED AT 400 WORDS)[11]

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].

References