title: Binding of glutamine to glutamine-binding protein from Escherichia coli induces changes in protein structure and increases protein stability.
abstract: 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 alpha-helices than beta-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.
authors.affiliation: Institute of Protein Biochemistry, CNR, Via Pietro Castellino, 111 Naples, Italy. s.dauria@ibp.cnr.it <s.dauria@ibp.cnr.it>
authors.forename: Sabato
authors.initials: S
authors.lastname: D'Auria
authors.forename: Andrea
authors.initials: A
authors.lastname: Scirè
authors.forename: Antonio
authors.initials: A
authors.lastname: Varriale
authors.forename: Viviana
authors.initials: V
authors.lastname: Scognamiglio
authors.forename: Maria
authors.initials: M
authors.lastname: Staiano
authors.forename: Alessio
authors.initials: A
authors.lastname: Ausili
authors.forename: Anna
authors.initials: A
authors.lastname: Marabotti
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Fabio
authors.initials: F
authors.lastname: Tanfani
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary / Q000502:physiology; D013816:Thermodynamics
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C037853:glutamine transport proteins; D005973:Glutamine