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Monoclonal antibody 4B1 influences the p K a of Glu325 in lactose permease (LacY) from Escherichia coli : evidence from SEIRAS
Author(s) -
Omeis Fatima,
Santos Seica Ana Filipa,
Ermolova Natalia,
Kaback H. Ronald,
Hellwig Petra
Publication year - 2020
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13907
Subject(s) - lactose permease , periplasmic space , chemistry , escherichia coli , monoclonal antibody , lactose , binding site , biochemistry , permease , biophysics , microbiology and biotechnology , antibody , biology , immunology , gene
The monoclonal antibody 4B1 binds to a conformational epitope on the periplasmic side of lactose permease (LacY) of Escherichia coli and inhibits H + /lactose symport and lactose efflux under nonenergized conditions. At the same time, ligand binding and translocation reactions that do not involve net H + translocation remain unaffected by 4B1. In this study, surface‐enhanced infrared absorption spectroscopy applied to the immobilized LacY was used to study the pH‐dependent changes in LacY and to access in situ the effect of the 4B1 antibody on the p K a of Glu325, the primary functional H + ‐binding site in LacY. A small shift of the p K value from 10.5 to 9.5 was identified that can be corroborated with the inactivation of LacY upon 4B1 binding.