title: Native-like partially folded conformations and folding process revealed in the N-terminal large fragments of staphylococcal nuclease: a study by NMR spectroscopy.
abstract: The N-terminal large fragments of staphylococcal nuclease (SNase), SNase110 (1-110 residues), SNase121 (1-121 residues), and SNase135 (1-135 residues), and the fragment mutants G88W110, G88W121, V66W110 and V66W121 were studied by heteronuclear multidimensional NMR spectroscopy. Ensembles of co-existent native-like partially folded and unfolded states were observed for fragments. The persistent native-like tertiary interaction drives fragments to be in partially folded states, which reveal native-like beta-barrel conformations. G88W and V66W mutations modulate the extent of inherent native-like tertiary interaction in fragment molecules, and in consequence, fragment mutants fold into native-like beta-subdomain conformations. In cooperation with the inherent tertiary interaction, 2 M TMAO (trimethylamine N-oxide) can promote the folding reaction of fragments through the changes of unfolding free energy, and a native-like beta-subdomain conformation is observed when the chain length contains 135 residues. Heterogeneous partially folded conformations of 1-121 and 1-135 fragments due to cis and trans X-prolyl bond of Lys116-Pro117 make a non-unique folding pathway of fragments. The folding reaction of fragments can be characterized as a hierarchical process.
authors.affiliation: National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, People's Republic of China.
authors.forename: Yingang
authors.initials: Y
authors.lastname: Feng
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Liu
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Wang
mesh_terms: D001665:Binding Sites; D009682:Magnetic Resonance Spectroscopy; D008836:Micrococcal Nuclease / Q000737:chemistry*; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D008836:Micrococcal Nuclease