title: Crystal structure and interaction of phycocyanin with β-secretase: A putative therapy for Alzheimer's disease.
abstract: Alzheimer's disease (AD) represents a neurological disorder, which is caused by enzymatic degradation of an amyloid precursor protein into short peptide fragments that undergo association to form insoluble plaques. Preliminary studies suggest that cyanobacterial extracts, especially the light-harvesting protein phycocyanin, may provide a means to control the progression of the disease. However, the molecular mechanism of disease control remains elusive. In the present study, intact hexameric phycocyanin was isolated and crystallized from the cyanobacterium Leptolyngbya sp. N62DM, and the structure was solved to a resolution of 2.6 A. Molecular docking studies show that the phycocyanin αβ-dimer interacts with the enzyme β-secretase, which catalyzes the proteolysis of the amyloid precursor protein to form plaques. The molecular docking studies suggest that the interaction between phycocyanin and β-secretase is energetically more favorable than previously reported inhibitor-β-secretase interactions. Transgenic Caenorhabditis elegans worms, with a genotype to serve as an AD-model, were significantly protected by phycocyanin. Therefore, the present study provides a novel structure-based molecular mechanism of phycocyanin-mediated therapy against AD.
authors.forename: Niraj Kumar
authors.initials: NK
authors.lastname: Singh
authors.forename: Syed S
authors.initials: SS
authors.lastname: Hasan
authors.forename: Jitendra
authors.initials: J
authors.lastname: Kumar
authors.forename: Isha
authors.initials: I
authors.lastname: Raj
authors.forename: Amrin A
authors.initials: AA
authors.lastname: Pathan
authors.forename: Asha
authors.initials: A
authors.lastname: Parmar
authors.forename: Shazi
authors.initials: S
authors.lastname: Shakil
authors.forename: Samudrala
authors.initials: S
authors.lastname: Gourinath
authors.affiliation: (Datta Madamwar) BRD School of Biosciences, Sardar Patel Maidan, Vadtal Road, Satellite Campus, Post Box No. 39, Sardar Patel University, Vallabh Vidyanagar-388 120, Gujarat, India. datta_madamwar@yahoo.com.
authors.forename: Datta
authors.initials: D
authors.lastname: Madamwar
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy / Q000201:enzymology; D053829:Amyloid Precursor Protein Secretases / Q000737:chemistry*; D000818:Animals; D030801:Animals, Genetically Modified; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D017173:Caenorhabditis elegans; D000458:Cyanobacteria; D004195:Disease Models, Animal; D062105:Molecular Docking Simulation; D018696:Neuroprotective Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D010243:Paralysis / Q000188:drug therapy / Q000201:enzymology; D010798:Phycocyanin / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D018696:Neuroprotective Agents; D010798:Phycocyanin; D053829:Amyloid Precursor Protein Secretases