title: Structural stability of GlcV, the nucleotide binding domain of the glucose ABC transporter of Sulfolobus solfataricus.
abstract: GlcV is the nucleotide binding domain of the ABC-type glucose transporter of the hyperthermoacidophile Sulfolobus solfataricus. GlcV consists of two domains, an N-terminal domain containing the typical nucleotide binding-fold and a C-terminal beta-barrel domain with unknown function. The unfolding and structural stability of the wild-type (wt) protein and three mutants that are blocked at different steps in the ATP hydrolytic cycle were studied. The G144A mutant is unable to dimerize, while the E166A and E166Q mutants are defective in ATP hydrolysis and dimer dissociation. Unfolding of the wt GlcV and G144A GlcV occurred with a single transition, whereas the E166A and E166Q mutants showed a second transition at a higher melting temperature indicating an increased stability of the ABCalpha/beta subdomain. The structural stability of GlcV was increased in the presence of nucleotides suggesting that the transition corresponds to the unfolding of the NBD domain. Unfolding of the C-terminal domain appears to occur at temperatures above the unfolding of the NBD which coincides with the aggregation of the protein. Analysis of the domain organization of GlcV by trypsin digestion demonstrates cleavage of the NBD domain into three fragments, while nucleotides protect against proteolysis. The cleaved GlcV protein retained the ability to bind nucleotides and to dimerize. These data indicate that the wt GlcV NBD domain unfolds as a single domain protein, and that its stability is modified by mutations in the glutamate after the Walker B motif and by nucleotide binding.
authors.affiliation: Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: Monika G
authors.initials: MG
authors.lastname: Pretz
authors.forename: Chris
authors.initials: C
authors.lastname: van der Does
authors.forename: Sonja-Verena
authors.initials: SV
authors.lastname: Albers
authors.forename: Gea
authors.initials: G
authors.lastname: Schuurman-Wolters
authors.forename: Arnold J M
authors.initials: AJ
authors.lastname: Driessen
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001386:Azides / Q000494:pharmacology; D002152:Calorimetry, Differential Scanning; D003432:Cross-Linking Reagents / Q000494:pharmacology; D051246:Glucose Transport Proteins, Facilitative / Q000737:chemistry*; D019791:Guanidine / Q000494:pharmacology; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry; D009154:Mutation / Q000235:genetics; D009711:Nucleotides / Q000378:metabolism; D019920:Photoaffinity Labels; D017510:Protein Folding; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D048229:Sulfolobus solfataricus / Q000737:chemistry* / Q000187:drug effects; D013816:Thermodynamics; D044366:Transition Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D001386:Azides; D003432:Cross-Linking Reagents; D051246:Glucose Transport Proteins, Facilitative; D050505:Mutant Proteins; D009711:Nucleotides; D019920:Photoaffinity Labels; C017040:8-azidoadenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D014357:Trypsin; D019791:Guanidine