Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
The pentameric B subunit of the type II heat-labile enterotoxin of Escherichia coli (LT-IIb-B5) is a potent signaling molecule capable of modulating innate immune responses. It has previously been shown that LT-IIb-B5, but not the LT-IIb-­B5 Ser74Asp variant [LT-IIb-B5(S74D)], activates Toll-like receptor (TLR2) signaling in macrophages. Consistent with this, the LT-IIb-B5(S74D) variant failed to bind TLR2, in contrast to LT-IIb-B5 and the LT-IIb-B5 Thr13Ile [LT-IIb-B5(T13I)] and LT-IIb-B5 Ser74Ala [LT-IIb-B5(S74A)] variants, which displayed the highest binding activity to TLR2. Crystal structures of the Ser74Asp, Ser74Ala and Thr13Ile variants of LT-­IIb-B5 have been determined to 1.90, 1.40 and 1.90 Å resolution, respectively. The structural data for the Ser74Asp variant reveal that the carboxylate side chain points into the pore, thereby reducing the pore size compared with that of the wild-type or the Ser74Ala variant B pentamer. On the basis of these crystallographic data, the reduced TLR2-binding affinity of the LT-IIb-B5(S74D) variant may be the result of the pore of the pentamer being closed. On the other hand, the explanation for the enhanced TLR2-binding activity of the LT-IIb-B5(S74A) variant is more complex as its activity is greater than that of the wild-type B pentamer, which also has an open pore as the Ser74 side chain points away from the pore opening. Data for the LT-IIb-B5(T13I) variant show that four of the five variant side chains point to the outside surface of the pentamer and one residue points inside. These data are consistent with the lack of binding of the LT-IIb-B5(T13I) variant to GD1a ganglioside.

Supporting information

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S0907444912038917/mh5069sup1.pdf
Supplementary material

PDB references: LT-IIb-B5(S74D), 4fnf; LT-IIb-B5(T13I), 4fo2; LT-IIb-B5(S74A), 4fp5


Subscribe to Acta Crystallographica Section D: Biological Crystallography

The full text of this article is available to subscribers to the journal.

If you have already registered and are using a computer listed in your registration details, please email support@iucr.org for assistance.

Buy online

You may purchase this article in PDF and/or HTML formats. For purchasers in the European Community who do not have a VAT number, VAT will be added at the local rate. Payments to the IUCr are handled by WorldPay, who will accept payment by credit card in several currencies. To purchase the article, please complete the form below (fields marked * are required), and then click on `Continue'.
E-mail address* 
Repeat e-mail address* 
(for error checking) 

Format*   PDF (US $40)
   HTML (US $40)
   PDF+HTML (US $50)
In order for VAT to be shown for your country javascript needs to be enabled.

VAT number 
(non-UK EC countries only) 
Country* 
 

Terms and conditions of use
Contact us

Follow Acta Cryst. D
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds