Structural basis for oligosaccharide recognition by Pyrococcus furiosus maltodextrin-binding protein.
A maltodextrin-binding protein from Pyrococcus furiosus (PfuMBP) has been overproduced in Escherichia coli, purified, and crystallized. The crystal structure of the protein bound to an oligosaccharide ligand was determined to 1.85 A resolution. The fold of PfuMBP is very similar to that of the orthologous MBP from E. coli (EcoMBP), despite the moderate level of sequence identity between the two proteins (27 % identity, 46 % similarity). PfuMBP is extremely resistant to heat and chemical denaturation, which may be attributed to a number of factors, such as a tightly packed hydrophobic core, clusters of isoleucine residues, salt-bridges, and the presence of proline residues in key positions. Surprisingly, an attempt to crystallize the complex of PfuMBP with maltose resulted in a structure that contained maltotriose in the ligand-binding site. The structure of the complex suggests that there is a considerable energy gain upon binding of maltotriose in comparison to maltose. Moreover, isothermal titration calorimetry experiments demonstrated that the binding of maltotriose to the protein is exothermic and tight, whereas no thermal effect was observed upon addition of maltose at three temperatures. Therefore, PfuMBP evidently is designed to bind oligosaccharides composed of three or more glucopyranose units.
Evdokimov
A G
AG
Protein Engineering Section, Macromolecular Crystallography Laboratory, National Cancer Institute-Frederick Cancer Research and Development Center, P.O. Box B, Frederick, MD 21702-1201, USA. eudokima@mail.ncifrc.gov
Anderson
D E
DE
Routzahn
K M
KM
Waugh
D S
DS
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002151:Calorimetry; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins; D006860:Hydrogen Bonding; D008320:Maltose / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism*; D033902:Periplasmic Binding Proteins; D011485:Protein Binding; D017433:Protein Structure, Secondary; D020027:Pyrococcus furiosus / Q000737:chemistry*; D016415:Sequence Alignment; D055672:Static Electricity; D013499:Surface Properties; D013816:Thermodynamics; D014312:Trisaccharides / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D009844:Oligosaccharides; D033902:Periplasmic Binding Proteins; D014312:Trisaccharides; C008317:maltotriose; D008320:Maltose