title: New structural insights into Golgi Reassembly and Stacking Protein (GRASP) in solution.
abstract: Among all proteins localized in the Golgi apparatus, a two-PDZ (PSD95/DlgA/Zo-1) domain protein plays an important role in the assembly of the cisternae. This Golgi Reassembly and Stacking Protein (GRASP) has puzzled researchers due to its large array of functions and relevance in Golgi functionality. We report here a biochemical and biophysical study of the GRASP55/65 homologue in Cryptococcus neoformans (CnGRASP). Bioinformatic analysis, static fluorescence and circular dichroism spectroscopies, calorimetry, small angle X-ray scattering, solution nuclear magnetic resonance, size exclusion chromatography and proteolysis assays were used to unravel structural features of the full-length CnGRASP. We detected the coexistence of regular secondary structures and large amounts of disordered regions. The overall structure is less compact than a regular globular protein and the high structural flexibility makes its hydrophobic core more accessible to solvent. Our results indicate an unusual behavior of CnGRASP in solution, closely resembling a class of intrinsically disordered proteins called molten globule proteins. To the best of our knowledge, this is the first structural characterization of a full-length GRASP and observation of a molten globule-like behavior in the GRASP family. The possible implications of this and how it could explain the multiple facets of this intriguing class of proteins are discussed.
authors.affiliation: Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Luís F S
authors.initials: LF
authors.lastname: Mendes
authors.affiliation: Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Assuero F
authors.initials: AF
authors.lastname: Garcia
authors.affiliation: Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Kumagai
authors.affiliation: Departamento de Física, Centro Multiusuário de Inovação Biomolecular, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Júlio Mesquita, São José do Rio Preto, Brazil.
authors.forename: Fabio R
authors.initials: FR
authors.lastname: de Morais
authors.affiliation: Departamento de Física, Centro Multiusuário de Inovação Biomolecular, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Júlio Mesquita, São José do Rio Preto, Brazil.
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Melo
authors.affiliation: Centro de Biotecnologia, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Livia
authors.initials: L
authors.lastname: Kmetzsch
authors.affiliation: Centro de Biotecnologia, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Marilene H
authors.initials: MH
authors.lastname: Vainstein
authors.affiliation: Fundação Oswaldo Cruz - Fiocruz, Centro de Desenvolvimento Tecnológico em Saúde (CDTS), Rio de Janeiro, Brazil.|Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marcio L
authors.initials: ML
authors.lastname: Rodrigues
authors.affiliation: Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Costa-Filho
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D054731:PDZ Domains; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D058767:Protein Unfolding; D012996:Solutions; D013329:Structure-Activity Relationship
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D012996:Solutions; C410230:tamalin protein, human