Compact molten globule-like state of hUBF HMG Box1 at extremely low pH

Biochim Biophys Acta. 2005 Apr 15;1748(1):66-73. doi: 10.1016/j.bbapap.2004.12.002. Epub 2005 Jan 25.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anilino Naphthalenesulfonates / chemistry
  • Circular Dichroism
  • Fluorescent Dyes / chemistry
  • Guanidine / chemistry
  • HMG-Box Domains*
  • High Mobility Group Proteins / chemistry
  • Humans
  • Hydrogen-Ion Concentration
  • Nuclear Magnetic Resonance, Biomolecular
  • Pol1 Transcription Initiation Complex Proteins / chemistry*
  • Protein Conformation*
  • Protein Denaturation
  • Protein Folding
  • Temperature

Substances

  • Anilino Naphthalenesulfonates
  • Fluorescent Dyes
  • High Mobility Group Proteins
  • Pol1 Transcription Initiation Complex Proteins
  • transcription factor UBF
  • 1-anilino-8-naphthalenesulfonate
  • Guanidine