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J Mol Biol. 1998 Dec 11;284(4):1223-37.

Self-interaction of pneumolysin, the pore-forming protein toxin of Streptococcus pneumoniae.

Author information

1
Department of Biochemistry, University of Leicester, Leicester, LE1 7RH, UK. gilbert@bioch.ox.ac.uk

Abstract

The pathogenically important cholesterol-binding pore-forming bacterial "thiol-activated" toxins (TATs) are commonly believed to be monomeric in solution and to undergo a transition on membrane binding mediated by cholesterol to an oligomeric pore. We present evidence, gained through the application of a number of biochemical and biophysical techniques with associated modelling, that the TAT from Streptococcus pneumoniae, pneumolysin, is in fact able to self-associate in solution to form the same oligomeric structures. The weak interaction leading to solution oligomerization is manifested at low concentrations in a dimeric toxin form. The inhibition of toxin self-interaction by derivatization of the single cysteine residue in pneumolysin with the thiol-active agent dithio (bis)nitrobenzoic acid indicates that self-interaction is mediated by the fourth domain of the protein, which has a fold similar to other proteins known to self-associate. This interaction is thought to have implications for the understanding of mechanisms of pore formation and complement activation by pneumolysin.

PMID:
9837740
DOI:
10.1006/jmbi.1998.2258
[Indexed for MEDLINE]

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