A stability transition at mildly acidic pH in the alpha-hemolysin (alpha-toxin) from Staphylococcus aureus.


Abstract

The effects of mildly acidic conditions on the free energy of unfolding (DeltaG(u)(buff)) of the pore-forming alpha-hemolysin (alphaHL) from Staphylococcus aureus were assessed between pH 5.0 and 7.5 by measuring intrinsic tryptophan fluorescence, circular dichroism and elution time in size exclusion chromatography during urea denaturation. Decreasing the pH from 7.0 to 5.0 reduced the calculated DeltaG(u)(buff) from 8.9 to 4.2 kcal mol(-1), which correlates with an increased rate of pore formation previously observed over the same pH range. It is proposed that the lowered surface pH of biological membranes reduces the stability of alphaHL thereby modulating the rate of pore formation. Study holds ProTherm entries: 15016, 15017, 15018, 15019, 15020, 15021, 15022, 15023 Extra Details: alpha-hemolysin; stability transition

Submission Details

ID: fjvDnx2z3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:45 p.m.

Version: 1

Publication Details
Bortoleto RK;Ward RJ,FEBS Lett. (1999) A stability transition at mildly acidic pH in the alpha-hemolysin (alpha-toxin) from Staphylococcus aureus. PMID:10526180
Additional Information

Number of data points 24
Proteins Alpha-hemolysin ; Alpha-hemolysin
Unique complexes 1
Assays/Quantities/Protocols Experimental Assay: Cm buffers:sodium phosphate: 20 mM, pH:7.0 ; Experimental Assay: m buffers:sodium phosphate: 20 mM, pH:7.0 ; Experimental Assay: dG_H2O buffers:sodium phosphate: 20 mM, pH:7.0 ; Experimental Assay: Cm pH:5.0, buffers:acetate: 20 mM ; Experimental Assay: m pH:5.0, buffers:acetate: 20 mM ; Experimental Assay: dG_H2O pH:5.0, buffers:acetate: 20 mM ; Experimental Assay: Cm pH:7.5, buffers:sodium phosphate: 20 mM ; Experimental Assay: m pH:7.5, buffers:sodium phosphate: 20 mM ; Experimental Assay: dG_H2O pH:7.5, buffers:sodium phosphate: 20 mM ; Experimental Assay: Cm buffers:sodium phosphate: 20 mM, pH:7.0 ; Experimental Assay: m buffers:sodium phosphate: 20 mM, pH:7.0 ; Experimental Assay: dG_H2O buffers:sodium phosphate: 20 mM, pH:7.0 ; Experimental Assay: Cm buffers:sodium phosphate: 20 mM, pH:6.5 ; Experimental Assay: m buffers:sodium phosphate: 20 mM, pH:6.5 ; Experimental Assay: dG_H2O buffers:sodium phosphate: 20 mM, pH:6.5 ; Experimental Assay: Cm pH:6.0, buffers:sodium phosphate: 20 mM ; Experimental Assay: m pH:6.0, buffers:sodium phosphate: 20 mM ; Experimental Assay: dG_H2O pH:6.0, buffers:sodium phosphate: 20 mM ; Experimental Assay: Cm pH:5.5, buffers:acetate: 20 mM ; Experimental Assay: m pH:5.5, buffers:acetate: 20 mM ; Experimental Assay: dG_H2O pH:5.5, buffers:acetate: 20 mM ; Experimental Assay: Cm pH:5.0, buffers:acetate: 20 mM ; Experimental Assay: m pH:5.0, buffers:acetate: 20 mM ; Experimental Assay: dG_H2O pH:5.0, buffers:acetate: 20 mM
Libraries Mutations for sequence ADSDINIKTGTTDIGSNTTVKTGDLVTYDKENGMHKKVFYSFIDDKNHNKKLLVIRTKGTIAGQYRVYSEEGANKSGLAWPSAFKVQLQLPDNEVAQISDYYPRNSIDTKEYMSTLTYGFNGNVTGDDTGKIGGLIGANVSIGHTLKYVQPDFKTILESPTDKKVGWKVIFNNMVNQNWGPYDRDSWNPVYGNQLFMKTRNGSMKAADNFLDPNKASSLLSSGFSPDFATVITMDRKASKQQTNIDVIYERVRDDYQLHWTSTNWKGTNTKDKWTDRSSERYKIDWEKEEMTN
Sequence Assay Result Units