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Binding of glutamine to glutamine‐binding protein from Escherichia coli induces changes in protein structure and increases protein stability
Author(s) -
D'Auria Sabato,
Scirè Andrea,
Varriale Antonio,
Scognamiglio Viviana,
Staiano Maria,
Ausili Alessio,
Marabotti Anna,
Rossi Mosè,
Tanfani Fabio
Publication year - 2004
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.20289
Subject(s) - glutamine , periplasmic space , amino acid , crystallography , escherichia coli , protein structure , chemistry , biochemistry , biophysics , binding protein , biology , gene
Glutamine‐binding protein (GlnBP) from Escherichia coli is a monomeric protein localized in the periplasmic space of the bacterium. It is responsible for the first step in the active transport of L‐glutamine across the cytoplasmic membrane. The protein consists of two similar globular domains linked by two peptide hinges, and X‐ray crystallographic data indicate that the two domains undergo large movements upon ligand binding. Fourier transform infrared spectroscopy (FTIR) was used to analyze the structure and thermal stability of the protein in detail. The data indicate that glutamine binding induces small changes in the secondary structure of the protein and that it renders the structure more thermostable and less flexible. Detailed analyses of IR spectra show a lower thermal sensitivity of α‐helices than β‐sheets in the protein both in the absence and in the presence of glutamine. Generalized two‐dimensional (2D) analyses of IR spectra reveal the same sequence of unfolding events in the protein in the absence and in the presence of glutamine, indicating that the amino acid does not affect the unfolding pathway of the protein. The data give new insight into the structural characteristics of GlnBP that are useful for both basic knowledge and biotechnological applications. Proteins 2005. © 2004 Wiley‐Liss, Inc.