Domain 4 of the anthrax protective antigen maintains structure and binding to the host receptor CMG2 at low pH

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Authors
Williams, Alexander S.
Lovell, Scott
Anbanandam, Asokan
El-Chami, Rahif
Bann, James G.
Issue Date
2009-11
Type
Article
Language
eng
Keywords
Research Support, N.I.H., Extramural
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Abstract

Domain 4 of the anthrax protective antigen (PA) plays a key role in cellular receptor recognition as well as in pH-dependent pore formation. We present here the 1.95 A crystal structure of domain 4, which adopts a fold that is identical to that observed in the full-length protein. We have also investigated the structural properties of the isolated domain 4 as a function of pH, as well as the pH-dependence on binding to the von Willebrand factor A domain of capillary morphogenesis protein 2 (CMG2). Our results provide evidence that the isolated domain 4 maintains structure and interactions with CMG2 at pH 5, a pH that is known to cause release of the receptor on conversion of the heptameric prepore (PA(63))(7) to a membrane-spanning pore. Our results suggest that receptor release is not driven solely by a pH-induced unfolding of domain 4.

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Citation
Protein science : a publication of the Protein Society. 2009 Nov; 18(11): 2277-86.
Publisher
John Wiley and Sons
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DOI
ISSN
1469-896X
0961-8368
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