Disease relevance of ECs5015

• 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].

High impact information on ECs5015

• Substitutions at the same positions in MalF and MalG have different phenotypes, indicating that EAA regions do not act symmetrically [1].
• 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 [3].
• Ligand translocation and ATP hydrolysis are dependent on a signaling mechanism originating from the binding protein and traveling through MalF/MalG [4].
• 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 [4].
• 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 [5].

Biological context of ECs5015

• 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 [6].
• 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)[7]
• The locations of different malE suppressor mutations indicate specific regions on MBP that are important for interacting with MalF and MalG [8].
• Comparisons of the amino acid sequences encoded by these genes indicate that they are homologous to the E. coli MalE periplasmic maltose binding protein and the two maltose permeases MalG and MalF [9].
• The sequence homology to the UgpE and MalG proteins of Escherichia coli was 27.6%, or 60.4 and 52.2%, respectively, taking into account the conservative amino acid changes [10].

Anatomical context of ECs5015

• In addition to the water-soluble maltose-binding protein, the system comprises three membrane proteins, MalF, MalG, and MalK, which form a heterotetrameric complex (FGK2) in the cytoplasmic membrane [11].
• 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].
• Wild-type and mutant proteins were detected in total bacterial extracts and on purified subcellular fractions with the help of an antibody prepared against a synthetic peptide based on the predicted N-terminal sequence of MalG [13].

Associations of ECs5015 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 [14].

Analytical, diagnostic and therapeutic context of ECs5015

• 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 [15].

References