Thermal stability and intersubunit interactions of cholera toxin in solution and in association with its cell-surface receptor ganglioside GM1.


Abstract

The thermal stability of cholera toxin free in solution and in association with its cell-surface receptor ganglioside GM1 has been studied by using high-sensitivity differential scanning calorimetry and differential solubility thermal gel analysis. In the absence of ganglioside GM1, cholera toxin undergoes two distinct thermally induced transitions centered at 51 and 74 degrees C, respectively. The low-temperature transition has been assigned to the irreversible thermal denaturation of the active A subunit. The second transition has been assigned to the reversible unfolding of the B subunit pentamer. The isolated B subunit pentamer exhibits a single transition also centered at 74 degrees C, suggesting that the attachment of the A subunit does not contribute to the stability of the pentamer. In the intact toxin, the A subunit dissociates from the B subunit pentamer at a temperature that coincides with the onset of the B subunit thermal unfolding. In aqueous solution, the denatured A subunit precipitates after dissociation from the B subunit pentamer. This phenomenon can be detected calorimetrically by the appearance of an exothermic heat effect. In the presence of ganglioside GM1, the B subunit is greatly stabilized as indicated by an increase of 20 degrees C in the transition temperature. In addition, ganglioside GM1 greatly enhances the cooperative interactions between B subunits. In the absence of ganglioside, each monomer within the B pentamer unfolds in an independent fashion whereas the fully ganglioside-bound pentamer behaves as a single cooperative unit. On the contrary, the thermotropic behavior of the A subunit is only slightly affected by the presence of increasing concentrations of ganglioside GM1.(ABSTRACT TRUNCATED AT 250 WORDS) Study holds ProTherm entries: 3884, 3885 Extra Details: additive : Na2EDTA(1 mM),NaN3(3 mM) was added in the experiment exothermic heat effect; cooperative interactions;,micellar; membrane-bound gangliosides

Submission Details

ID: kQDPHnwV4

Submitter: Connie Wang

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

Version: 1

Publication Details
Goins B;Freire E,Biochemistry (1988) Thermal stability and intersubunit interactions of cholera toxin in solution and in association with its cell-surface receptor ganglioside GM1. PMID:3378043
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
1P9R 2003-05-12T00:00:00+0000 2.5 Crystal Structure of Vibrio cholerae putative NTPase EpsE
1P9W 2003-05-12T00:00:00+0000 2.7 Crystal Structure of Vibrio cholerae putative NTPase EpsE
2BH1 2005-01-06T00:00:00+0000 2.4 X-ray structure of the general secretion pathway complex of the N- terminal domain of EpsE and the cytosolic domain of EpsL of Vibrio cholerae
4KSR 2013-05-17T00:00:00+0000 4.2 Crystal Structure of the Vibrio cholerae ATPase GspE Hexamer
4KSS 2013-05-17T00:00:00+0000 7.58 Crystal Structure of Vibrio cholerae ATPase GspsE Hexamer
1CHP 1995-02-15T00:00:00+0000 2.0 SURPRISING LEADS FOR A CHOLERA TOXIN RECEPTOR BINDING ANTAGONIST; CRYSTALLOGRAPHIC STUDIES OF CTB MUTANTS
1CHQ 1995-02-15T00:00:00+0000 2.1 SURPRISING LEADS FOR A CHOLERA TOXIN RECEPTOR BINDING ANTAGONIST; CRYSTALLOGRAPHIC STUDIES OF CTB MUTANTS
1CT1 1997-06-03T00:00:00+0000 2.3 CHOLERA TOXIN B-PENTAMER MUTANT G33R BOUND TO RECEPTOR PENTASACCHARIDE
1FGB 1996-02-21T00:00:00+0000 2.4 TOXIN
1G8Z 2000-11-21T00:00:00+0000 2.0 HIS57ALA MUTANT OF CHOLERA TOXIN B-PENATMER

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Type II secretion system protein E P37093 GSPE_VIBCH
97.1 Cholera enterotoxin subunit B P01556 CHTB_VIBCH