1ilo

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Template:STRUCTURE 1ilo

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. 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 Fri May 2 20:07:52 2008