Compact molten globule-like state of hUBF HMG Box1 at extremely low pH.
Using far and near-UV CD, ANS fluorescence and 2D NMR spectroscopy, an acid-induced partly folded state (A state) at extremely low pH for hUBF HMG Box1 was identified and characterized. As compared to the native state (N), the A state has similar secondary structure, less compact pack with larger amounts of exposed hydrophobic surface, and narrower chemical shift dispersion in (1)H-(15)N HSQC spectrum, which implies that it is a molten globule (MG)-like species. On the other hand, substantial tertiary contacts and cooperative thermal denaturing transition indicate that the A state is closer-relative to the classic MG-to the native folded state. In addition, when the solution pH is adjusted to neutrality, the protein in the A state refolds to the native state easily. All these data suggest that the A state of hUBF HMG Box1 could represent a potential folding intermediate on protein folding pathway.
Zhang
Xuecheng
X
School of Life Science, University of Science and Technology of China, People's Republic of China.
Zhang
Jiahai
J
Li
Xuan
X
Xu
Junjie
J
Huang
Hongda
H
Chen
Quan
Q
Wu
Jihui
J
Shi
Yunyu
Y
D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D002942:Circular Dichroism; D005456:Fluorescent Dyes / Q000737:chemistry; D019791:Guanidine / Q000737:chemistry; D024742:HMG-Box Domains; D006609:High Mobility Group Proteins / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019906:Nuclear Magnetic Resonance, Biomolecular; D035463:Pol1 Transcription Initiation Complex Proteins / Q000737:chemistry*; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D013696:Temperature
D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D006609:High Mobility Group Proteins; D035463:Pol1 Transcription Initiation Complex Proteins; C063844:transcription factor UBF; C027132:1-anilino-8-naphthalenesulfonate; D019791:Guanidine