Thermodynamic measurements of the contributions of helix-connecting loops and of retinal to the stability of bacteriorhodopsin.


Abstract

Thermodynamic studies of bacteriorhodopsin (BR) have been undertaken in order to investigate the factors that stabilize the structure of a membrane protein. The stability of the native, intact protein was compared to that of protein with retinal removed, and/or cleaved in one or two of the loops connecting the transmembrane helices. The stability was assessed using differential scanning calorimetry and thermal denaturation curves obtained from ultraviolet circular dichroism and absorption spectroscopy. Retinal binding and the loop connections were each found to make a small contribution to stability, and even a sample that was cleaved twice as well as bleached to remove retinal denatured well above room temperature. Removal of retinal destabilized the protein more than cleaving once, and about as much as cleaving twice. Retinal binding and the connections in the loops were found to stabilize BR in independent ways. Cleavage of the molecule into fragments did not reduce the intermolecular cooperativity of the denaturation. Dilution of the protein by addition of excess lipid in order to eliminate the purple membrane crystal lattice also did not alter the cooperativity. These results are used to compare the relative importance of various contributors to the stability of BR. Study holds ProTherm entries: 4032, 4033 Extra Details: membrane protein; retinal binding; loop connections;,purple membrane; cooperativity

Submission Details

ID: fwSU4akH4

Submitter: Connie Wang

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

Version: 1

Publication Details
Kahn TW;Sturtevant JM;Engelman DM,Biochemistry (1992) Thermodynamic measurements of the contributions of helix-connecting loops and of retinal to the stability of bacteriorhodopsin. PMID:1390670
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