1hfo

From Proteopedia

Revision as of 14:30, 5 November 2007

THE STRUCTURE OF THE MACROPHAGE MIGRATION INHIBITORY FACTOR FROM TRICHINELLA SPIRALIS.

Overview

cDNAs were obtained for macrophage migration-inhibitory factor, (MIF)/L-dopachrome methyl ester tautomerase homologues from the parasitic, nematodes Trichinella spiralis (TsMIF) and Trichuris trichiura (TtMIF)., The translated sequences, which were partly confirmed by sequencing of, proteolytic fragments, show 42 and 44% identity respectively with human or, mouse MIF, and are shorter by one C-terminal residue. Unlike vertebrate, MIF and MIF homologues of filarial nematodes, neither TsMIF nor TtMIF, contain cysteine residues. Soluble recombinant TsMIF, expressed in, Escherichia coli showed secondary structure (by CD spectroscopy) and, quaternary structure (by light-scattering and gel filtration) similar to, that of the trimeric mammalian MIFs and D-dopachrome tautomerase. The, catalytic specificity of recombinant TsMIF in the ketonization of, phenylpyruvate (1.4x10(6) M(-1) x s(-1)) was comparable with that of human, MIF, while that of p-hydroxyphenylpyruvate (9.1x10(4) M(-1) x s(-1)) was, 71-fold lower. TsMIF showed high specificity in tautomerization of the, methyl ester of L-dopachrome compared with non-esterified L-dopachrome, (>87000-fold) and a high kcat (approximately 4x10(4) s(-1). The crystal, structure, determined to 1.65 A (1 A=0.1 nm), was generally similar to, that of human MIF, but differed in the boundaries of the putative, active-site pocket, which can explain the low activity towards, p-hydroxyphenylpyruvate. The central pore was blocked, but was continuous, with the three putative tautomerase sites. Recombinant TsMIF (5 ng/ml-5, pg/ml) inhibited migration of human peripheral-blood mononuclear cells in, a manner similar to that shown by human MIF, but had no effect from 5 to, 500 ng/ml on anti-CD3-stimulated murine T-cell proliferation. TsMIF was, detected in supernatants of T. spiralis larvae cultured in vitro at 6, ng/ml (55 ng/mg total secreted protein). In conclusion TsMIF has, structural, catalytic and cell-migration-inhibitory properties which, indicate that it is partially orthologous to mammalian MIF.

About this Structure

1HFO is a Single protein structure of sequence from Trichinella spiralis. Structure known Active Sites: DTA, DTB, DTC, DTD, DTE and DTF. Full crystallographic information is available from OCA.

Reference

Macrophage migration inhibitory factor of the parasitic nematode Trichinella spiralis., Tan TH, Edgerton SA, Kumari R, McAlister MS, Roe SM, Nagl S, Pearl LH, Selkirk ME, Bianco AE, Totty NF, Engwerda C, Gray CA, Meyer DJ, Biochem J. 2001 Jul 15;357(Pt 2):373-83. PMID:11439086

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