PDBsum entry 4mo7

Transcription

PDB id: 4mo7

Contents

Protein chain

188 a.a.

Ligands

BME

Metals

_MG

Waters ×111

PDB id:

4mo7

Name:

Transcription

Title:

Crystal structure of superantigen pfit

Structure:

Transcriptional regulator i2. Chain: a. Engineered: yes

Source:

Pseudomonas fluorescens a506. Organism_taxid: 1037911. Gene: pfit, pfla506_3695. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

1.70Å R-factor: 0.191 R-free: 0.234

Authors:

L.H.Liu,H.Chen,H.M.Li

Key ref:

L.Liu et al. (2013). Pfit is a structurally novel Crohn's disease-associated superantigen. Plos Pathog, 9, e1003837. PubMed id: 24385909 DOI: 10.1371/journal.ppat.1003837

Date:

11-Sep-13 Release date: 05-Feb-14

Protein chain

I2BPL4  (I2BPL4_PSEFL) -

DOI no: 10.1371/journal.ppat.1003837

Plos Pathog 9:e1003837 (2013)

PubMed id: 24385909

Pfit is a structurally novel Crohn's disease-associated superantigen.

L.Liu, H.Chen, M.B.Brecher, Z.Li, B.Wei, B.Nandi, J.Zhang, H.Ling, G.Winslow, J.Braun, H.Li.

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 1.7Å 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.