title: Correlation between Al(3+) -induced thermal stability and inhibition of fibrillation of N-terminal domain of the hydrogenase maturation factor.
abstract: Fibrillation can be induced in proteins by altering solvent conditions. Stabilization of the protofibrillar structure arrests formation of longer fibers. Thermal stability and fibrillation of N-terminal domain of the hydrogenase maturation factor (HypF-N) were studied in the presence of a series of metal ions. Only Al(3+) was able to reverse the thermal denaturation of HypF-N upon heating. On being exposed to denaturing conditions, the native protein formed fibrillar structure under moderately denaturing conditions, whereas in the presence of Al(3+) , the protein was found to retain its native conformation. Under strongly denaturing conditions, only Al(3+) was able to stabilize the protein in the fibrillar state. Spectrofluorimetric analysis revealed that Al(3+) alone was able to stabilize the partially unfolded intermediate state of HypF-N. Based on the similarity in observations, we propose a link between reversal of thermal instability of HypF-N and its ability to form an intermediate structure in the presence of Al(3+) . Al(3+) stabilizes the partially unfolded state in the N↔I↔U equilibrium so that upon heating, the three-dimensional structure of the protein is not lost completely. Kinetic analysis confirmed that Al(3+) interacts with an early structure on the aggregation landscape and delays fibrillation. Under mildly denaturing state, HypF-N is able to recover its native conformation in the presence of Al(3+) and under strongly denaturing conditions, the protein does not acquire a completely disordered structure. Instead, it forms an ordered β-sheet-rich structure.
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India.
authors.forename: Nimesh M
authors.initials: NM
authors.lastname: Sutariya
authors.forename: Shivcharan
authors.initials: S
authors.lastname: Prasad
authors.forename: Dipti A
authors.initials: DA
authors.lastname: Athavale
authors.forename: Rupen D
authors.initials: RD
authors.lastname: Bhavsar
authors.forename: Ipsita
authors.initials: I
authors.lastname: Roy
mesh_terms: D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry*; D000682:Amyloid / Q000737:chemistry*; D019878:Carboxyl and Carbamoyl Transferases / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D004795:Enzyme Stability; D029968:Escherichia coli Proteins / Q000737:chemistry*; D007700:Kinetics; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D044366:Transition Temperature
chemical_list: D017607:Aluminum Compounds; D000682:Amyloid; D002712:Chlorides; D029968:Escherichia coli Proteins; D000077410:Aluminum Chloride; D019878:Carboxyl and Carbamoyl Transferases; C504838:hypF protein, E coli
keywords: HypF-N; metal ions; protein fibrillation; protein stabilization; thermal stability