1cz5

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NMR STRUCTURE OF VAT-N: THE N-TERMINAL DOMAIN OF VAT (VCP-LIKE ATPASE OF THERMOPLASMA)

Overview

BACKGROUND: The VAT protein of the archaebacterium Thermoplasma, acidophilum, like all other members of the Cdc48/p97 family of AAA, ATPases, has two ATPase domains and a 185-residue amino-terminal, substrate-recognition domain, VAT-N. VAT shows activity in protein folding, and unfolding and thus shares the common function of these ATPases in, disassembly and/or degradation of protein complexes. RESULTS: Using, nuclear magnetic resonance (NMR) spectroscopy, we found that VAT-N is, composed of two equally sized subdomains. The amino-terminal subdomain, VAT-Nn (comprising residues Met1-Thr92) forms a double-psi beta-barrel, whose pseudo-twofold symmetry is mirrored by an internal sequence repeat, of 42 residues. The carboxy-terminal subdomain VAT-Nc (comprising residues, Glu93-Gly185) forms a novel six-stranded beta-clam fold. Together, VAT-Nn, and VAT-Nc form a kidney-shaped structure, in close agreement with results, from electron microscopy. Sequence and structure analyses showed that, VAT-Nn is related to numerous proteins including prokaryotic transcription, factors, metabolic enzymes, the protease cofactors UFD1 and PrlF, and, aspartic proteinases. These proteins map out an evolutionary path from, simple homodimeric transcription factors containing a single copy of the, VAT-Nn repeat to complex enzymes containing four copies. CONCLUSIONS: Our, results suggest that VAT-N is a precursor of the aspartic proteinases that, has acquired peptide-binding activity while remaining proteolytically, incompetent. We propose that the binding site of the protein is similar to, that of aspartic proteinases, in that it lies between the psi-loops of the, amino-terminal beta-barrel and that it coincides with a crescent-shaped, band of positive charge extending across the upper face of the molecule.

About this Structure

1CZ5 is a Single protein structure of sequence from Thermoplasma acidophilum. Full crystallographic information is available from OCA.

Reference

The solution structure of VAT-N reveals a 'missing link' in the evolution of complex enzymes from a simple betaalphabetabeta element., Coles M, Diercks T, Liermann J, Groger A, Rockel B, Baumeister W, Koretke KK, Lupas A, Peters J, Kessler H, Curr Biol. 1999 Oct 21;9(20):1158-68. PMID:10531028

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