Gas phase characterization of the noncovalent quaternary structure of cholera toxin and the cholera toxin B subunit pentamer
UNSPECIFIED. (2006) Gas phase characterization of the noncovalent quaternary structure of cholera toxin and the cholera toxin B subunit pentamer. BIOPHYSICAL JOURNAL, 90 (9). pp. 3246-3254. ISSN 0006-3495Full text not available from this repository.
Official URL: http://dx.doi.org/10.1529/biophysj.105.076455
Cholera toxin (CTx) is an AB(5) cytotonic protein that has medical relevance in cholera and as a novel mucosal adjuvant. Here, we report an analysis of the noncovalent homopentameric complex of CTx B chain ( CTx B-5) using electrospray ionization triple quadrupole mass spectrometry and tandem mass spectrometry and the analysis of the noncovalent hexameric holotoxin usingelectrospray ionization time-of-flight mass spectrometry over a range of pH values that correlate with those encountered by this toxin after cellular uptake. We show that noncovalent interactions within the toxin assemblies were maintained under both acidic and neutral conditions in the gas phase. However, unlike the related Escherichia coli Shiga-like toxin B-5 pentamer (SLTx B), the CTx B-5 pentamer was stable at low pH, indicating that additional interactions must be present within the latter. Structural comparison of the CTx B monomer interface reveals an additional alpha-helix that is absent in the SLTx B monomer. In silico energy calculations support interactions between this helix and the adjacent monomer. These data provide insight into the apparent stabilization of CTx B relative to SLTx B.
|Item Type:||Journal Article|
|Subjects:||Q Science > QH Natural history > QH301 Biology|
|Journal or Publication Title:||BIOPHYSICAL JOURNAL|
|Number of Pages:||9|
|Page Range:||pp. 3246-3254|
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