4MXM: Crystal Structure Of Superantigen Pfit

Citation:
Abstract
T cell responses to enteric bacteria are important in inflammatory bowel disease. I2, encoded by the pfiT gene of Pseudomonas fluorescens, is a T-cell superantigen associated with human Crohn's disease. Here we report the crystal structure of pfiT at 1.7A resolution and provide a functional analysis of the interaction of pfiT and its homolog, PA2885, with human class II MHC. Both pfiT and PA2885 bound to mammalian cells and stimulated the proliferation of human lymphocytes. This binding was greatly inhibited by anti-class II MHC HLA-DR antibodies, and to a lesser extent, by anti HLA-DQ and DP antibodies, indicating that the binding was class II MHC-specific. GST-pfiT efficiently precipitated both endogenous and in vitro purified recombinant HLA-DR1 molecules, indicating that pfiT directly interacted with HLA-DR1. Competition studies revealed that pfiT and the superantigen Mycoplasma arthritidis mitogen (MAM) competed for binding to HLA-DR, indicating that their binding sites overlap. Structural analyses established that pfiT belongs to the TetR-family of DNA-binding transcription regulators. The distinct structure of pfiT indicates that it represents a new family of T cell superantigens.
PDB ID: 4MXMDownload
MMDB ID: 123198
PDB Deposition Date: 2013/9/26
Updated in MMDB: 2014/09
Experimental Method:
x-ray diffraction
Resolution: 1.95  Å
Source Organism:
Similar Structures:
Biological Unit for 4MXM: dimeric; determined by author and by software (PISA)
Molecular Components in 4MXM
Label Count Molecule
Proteins (2 molecules)
2
Transcriptional Regulator I2
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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