Caveolin-1 binding motif of alpha-hemolysin: its role in stability and pore formation.
We have identified a nine amino sequence in alpha-hemolysin (alpha-HL) of Staphylococcus aureus, which binds Caveolin-1. Surface plasmon resonance studies clearly show a concentration dependent interaction of alpha-HL with the scaffolding domain of Caveolin-1. Mutants of alpha-HL, devoid of Caveolin-1 recognition motif, exhibit an alpha-HL like proteinase K digestion profile but the resultant 'half-like' domains are highly susceptible to further proteolysis. They also had the same intrinsic fluorescence emission maxima as the native alpha-HL indicating normal folding. However, these mutants bind 1-anilino-8-naphthalene sulfonic acid probably due to exposure of their hydrophobic core. Moreover, these mutants are non-lytic and do not undergo conformational changes on rabbit RBC membrane surface. Purified Caveolin-1 blocks the hemolysis of RBCs by alpha-HL. Our studies indicate that the Caveolin-1 binding motif of alpha-HL provides stability and shields the hydrophobic core of alpha-HL. The motif also acts as trigger point for initiation of conformational changes.
National Centre for Cell Science, Ganeshkhind Road, Pune 411007, Maharashtra, India.
Satyabrata
S
Pany
Ravi
R
Vijayvargia
M V
MV
Krishnasastry
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D051242:Caveolin 1; D022461:Caveolins / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016062:Porosity; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship
D001427:Bacterial Toxins; D051242:Caveolin 1; D022461:Caveolins; D006460:Hemolysin Proteins; D011994:Recombinant Proteins; C021091:staphylococcal alpha-toxin