title: Conversion of a maltose receptor into a zinc biosensor by computational design.
abstract: We have demonstrated that it is possible to radically change the specificity of maltose binding protein by converting it into a zinc sensor using a rational design approach. In this new molecular sensor, zinc binding is transduced into a readily detected fluorescence signal by use of an engineered conformational coupling mechanism linking ligand binding to reporter group response. An iterative progressive design strategy led to the construction of variants with increased zinc affinity by combining binding sites, optimizing the primary coordination sphere, and exploiting conformational equilibria. Intermediates in the design series show that the adaptive process involves both introduction and optimization of new functions and removal of adverse vestigial interactions. The latter demonstrates the importance of the rational design approach in uncovering cryptic phenomena in protein function, which cannot be revealed by the study of naturally evolved systems.
authors.affiliation: Department of Biochemistry, Box 3711, Duke University Medical Center, Durham, NC 27701, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Marvin
authors.forename: H W
authors.initials: HW
authors.lastname: Hellinga
mesh_terms: D000409:Alanine / Q000235:genetics; D000494:Allosteric Regulation; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D015374:Biosensing Techniques; D002151:Calorimetry; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003198:Computer Simulation; D005453:Fluorescence; D007700:Kinetics; D008024:Ligands; D008320:Maltose / Q000378:metabolism; D058619:Maltose-Binding Proteins; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011487:Protein Conformation; D015202:Protein Engineering / Q000379:methods*; D015398:Signal Transduction; D012984:Software; D013379:Substrate Specificity; D013696:Temperature; D013816:Thermodynamics; D015032:Zinc / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008024:Ligands; D058619:Maltose-Binding Proteins; D008320:Maltose; D015032:Zinc; D000409:Alanine