pH dependence of bacteriorhodopsin thermal unfolding.


Abstract

The thermal denaturation of bacteriorhodopsin in the purple membrane of Halobacterium halobium has been studied by differential scanning calorimetry (DSC) and temperature-dependent spectroscopy in the pH range from 5 to 11. Monitoring of protein fluorescence and absorbance in the near-UV and visible regions indicates that changes primarily occur in tertiary structure with denaturation. Far-UV circular dichroism shows only small changes in the secondary structure, unlike most globular water-soluble proteins of comparable molecular weight. The DSC transition can best be described as a two-state denaturation of the trimer. Thermodynamic analysis of the calorimetric transition reveals some similarity between the unfolding of bacteriorhodopsin and water-soluble proteins. Specifically, a pH dependence of the midpoint temperature of denaturation is seen as well as a temperature-dependent enthalpy of denaturation. Proteolysis experiments on denatured purple membrane suggest that bacteriorhodopsin may be partially extruded from the membrane as it denatures. Exposure of buried hydrophobic residues to the aqueous environment upon denaturation is consistent with the observed temperature-dependent enthalpy. Study holds ProTherm entries: 3918 Extra Details: tertiary structure; secondary structure;,buried hydrophobic residues; temperature-dependent enthalpy

Submission Details

ID: aAZ8PkT9

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:23 p.m.

Version: 1

Publication Details
Brouillette CG;Muccio DD;Finney TK,Biochemistry (1987) pH dependence of bacteriorhodopsin thermal unfolding. PMID:3427085
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
1AP9 1997-07-26T00:00:00+0000 2.35 X-RAY STRUCTURE OF BACTERIORHODOPSIN FROM MICROCRYSTALS GROWN IN LIPIDIC CUBIC PHASES
1AT9 1997-08-20T00:00:00+0000 3.0 STRUCTURE OF BACTERIORHODOPSIN AT 3.0 ANGSTROM DETERMINED BY ELECTRON CRYSTALLOGRAPHY
1BCT 1993-07-07T00:00:00+0000 0 THREE-DIMENSIONAL STRUCTURE OF PROTEOLYTIC FRAGMENT 163-231 OF BACTERIOOPSIN DETERMINED FROM NUCLEAR MAGNETIC RESONANCE DATA IN SOLUTION
1BHA 1993-10-11T00:00:00+0000 0 THREE-DIMENSIONAL STRUCTURE OF (1-71) BACTERIOOPSIN SOLUBILIZED IN METHANOL-CHLOROFORM AND SDS MICELLES DETERMINED BY 15N-1H HETERONUCLEAR NMR SPECTROSCOPY
1BHB 1993-10-11T00:00:00+0000 0 Three-dimensional structure of (1-71) bacterioopsin solubilized in methanol-chloroform and SDS micelles determined by 15N-1H heteronuclear NMR spectroscopy
1BM1 1998-07-28T00:00:00+0000 3.5 CRYSTAL STRUCTURE OF BACTERIORHODOPSIN IN THE LIGHT-ADAPTED STATE
1BRD 1990-05-23T00:00:00+0000 3.5 Model for the structure of Bacteriorhodopsin based on high-resolution Electron Cryo-microscopy
1BRR 1998-07-28T00:00:00+0000 2.9 X-RAY STRUCTURE OF THE BACTERIORHODOPSIN TRIMER/LIPID COMPLEX
1BRX 1998-05-28T00:00:00+0000 2.3 BACTERIORHODOPSIN/LIPID COMPLEX
1C3W 1999-07-28T00:00:00+0000 1.55 BACTERIORHODOPSIN/LIPID COMPLEX AT 1.55 A RESOLUTION

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Bacteriorhodopsin P02945 BACR_HALSA