1ilo

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NMR structure of a thioredoxin, MtH895, from the archeon Methanobacterium thermoautotrophicum strain delta H.

Overview

As part of a high-throughput, structural proteomic project we have used, NMR spectroscopy to determine the solution structure and ascertain the, function of a previously unknown, conserved protein (MtH895) from the, thermophilic archeon Methanobacterium thermoautotrophicum. Our findings, indicate that MtH895 contains a central four-stranded beta-sheet core, surrounded by two helices on one side and a third on the other. It has an, overall fold superficially similar to that of a glutaredoxin. However, detailed analysis of its three-dimensional structure along with molecular, docking simulations of its interaction with T7 DNA polymerase (a, thioredoxin-specific substrate) and comparisons with other known members, of the thioredoxin/glutaredoxin family of proteins strongly suggest that, MtH895 is more akin to a thioredoxin. Furthermore, measurement of the, pK(a) values of its active site thiols along with direct measurements of, the thioredoxin/glutaredoxin activity has confirmed that MtH895 is, indeed, a thioredoxin and exhibits no glutaredoxin activity. We have also, identified a group of previously unknown proteins from several other, archaebacteria that have significant (34-44%) sequence identity with, MtH895. These proteins have unusual active site -CXXC- motifs not found in, any known thioredoxin or glutaredoxin. On the basis of the results, presented here, we predict that these small proteins are all members of a, new class of truncated thioredoxins.

About this Structure

1ILO is a Single protein structure of sequence from Methanothermobacter thermautotrophicus. Active as Phosphoadenylyl-sulfate reductase (thioredoxin), with EC number 1.8.4.8 Full crystallographic information is available from OCA.

Reference

Identification of a novel archaebacterial thioredoxin: determination of function through structure., Bhattacharyya S, Habibi-Nazhad B, Amegbey G, Slupsky CM, Yee A, Arrowsmith C, Wishart DS, Biochemistry. 2002 Apr 16;41(15):4760-70. PMID:11939770

Page seeded by OCA on Sat Nov 24 22:11:05 2007