Cysteine-Scanning Mutagenesis of Transmembrane Domain XII and the Flanking Periplasmic Loop in the Lactose Permease of Escherichia coli

Using a functional lactose permease mutant devoid of Cys residues (C-less permease), each amino acid residue in transmembrane domain XII and the periplasmic loop between putative helices XI and XII (loop XI/XII) was replaced individually with Cys. Out of 34 mutants, 31 exhibit 60−100% or more of C-l...

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Bibliographic Details
Published in:Biochemistry (Easton) 1996-10, Vol.35 (39), p.12909-12914
Main Authors: He, Molly M, Sun, Jianzhong, Kaback, H. Ronald
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Biological Transport
Blotting, Western
Cell Membrane - enzymology
Cysteine - chemistry
Escherichia coli
Escherichia coli - enzymology
Escherichia coli - genetics
Escherichia coli Proteins
Ethylmaleimide - pharmacology
Lactose - metabolism
Membrane Transport Proteins - chemistry
Membrane Transport Proteins - genetics
Membrane Transport Proteins - metabolism
Models, Molecular
Molecular Sequence Data
Monosaccharide Transport Proteins
Mutagenesis, Site-Directed
Protein Structure, Secondary
Symporters
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Summary:Using a functional lactose permease mutant devoid of Cys residues (C-less permease), each amino acid residue in transmembrane domain XII and the periplasmic loop between putative helices XI and XII (loop XI/XII) was replaced individually with Cys. Out of 34 mutants, 31 exhibit 60−100% or more of C-less activity, mutants Gly377 → Cys and Leu385 → Cys exhibit lower rates of transport but accumulate lactose about 60−70% as well as C-less, and mutant Leu400 → Cys exhibits
ISSN:0006-2960
1520-4995
DOI:10.1021/bi960876b