Binding of monoclonal antibody 4B1 to homologs of the lactose permease of Escherichia coli
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Ημερομηνία
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peer-reviewed
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Όνομα περιοδικού
Protein Sci
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Περιγραφή
The conformationally sensitive epitope for monoclonal antibody (mAb) 4B1, which uncouples lactose from H+ translocation in the lactose permease of Escherichia coli, is localized in the periplasmic loop between helices VII and VIII (loop VII/VIII) on one face of a short helical segment (Sun J, et al., 1996, Biochemistry 35;990-998). Comparison of sequences in the region corresponding to loop VII/VIII in members of Cluster 5 of the Major Facilitator Superfamily (MFS), which includes five homologous oligosaccharide/H+ symporters, reveals interesting variations. 4B1 binds to the Citrobacter freundii lactose permease or E. coli raffinose permease with resultant inhibition of transport activity. Because E. coli raffinose permease contains a Pro residue at position 254 rather than Gly, it is unlikely that the mAb recognizes the peptide backbone at this position. Consistently, E. coli lactose permease with Pro in place of Gly254 also binds 4B1. In contrast, 4B1 binding is not observed with either Klebsiella pneumoniae lactose permease or E. coli sucrose permease. When the epitope is transferred from E. coli lactose permease (residues 245-259) to the sucrose permease, the modified protein binds 4B1, but the mAb has no significant effect on sucrose transport. The studies provide further evidence that the 4B1 epitope is restricted to loop VII/VIII, and that 4B1 binding induces a highly specific conformational change that uncouples substrate and H+ translocation.
Περιγραφή
Λέξεις-κλειδιά
Amino Acid Sequence, Antibodies, Bacterial, Antibodies, Monoclonal, Binding Sites, Biological Transport, Epitopes, Escherichia coli/*enzymology/genetics, *Escherichia coli Proteins, Membrane Transport Modulators, Membrane Transport Proteins/antagonists &, inhibitors/genetics/*immunology/*metabolism, Membranes/metabolism, Molecular Sequence Data, *Monosaccharide Transport Proteins, Mutagenesis, Site-Directed, Protein Structure, Secondary, Species Specificity, Spheroplasts/metabolism, *Symporters
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Παραπομπή
Σύνδεσμος
http://www.ncbi.nlm.nih.gov/pubmed/9232651
http://onlinelibrary.wiley.com/store/10.1002/pro.5560060714/asset/5560060714_ftp.pdf?v=1&t=h0byybcx&s=9ad0ef1e81c10a9fe7870771b5e587d33aa67918
http://onlinelibrary.wiley.com/store/10.1002/pro.5560060714/asset/5560060714_ftp.pdf?v=1&t=h0byybcx&s=9ad0ef1e81c10a9fe7870771b5e587d33aa67918
Γλώσσα
en
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Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής