1n25

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Revision as of 06:57, 18 November 2007

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spinqualitylabelsall models 1n25, resolution 2.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of the SV40 Large T antigen helicase domain

Overview

The oncoprotein large tumour antigen (LTag) is encoded by the DNA tumour, virus simian virus 40. LTag transforms cells and induces tumours in, animals by altering the functions of tumour suppressors (including pRB and, p53) and other key cellular proteins. LTag is also a molecular machine, that distorts/melts the replication origin of the viral genome and unwinds, duplex DNA. LTag therefore seems to be a functional homologue of the, eukaryotic minichromosome maintenance (MCM) complex. Here we present the, X-ray structure of a hexameric LTag with DNA helicase activity. The, structure identifies the p53-binding surface and reveals the structural, basis of hexamerization. The hexamer contains a long, positively charged, channel with an unusually large central chamber that binds both, single-stranded and double-stranded DNA. The hexamer organizes into two, tiers that can potentially rotate relative to each other through, connecting alpha-helices to expand/constrict the channel, producing an, 'iris' effect that could be used for distorting or melting the origin and, unwinding DNA at the replication fork.

About this Structure

1N25 is a Single protein structure of sequence from Simian virus 40 with ZN as ligand. The following page contains interesting information on the relation of 1N25 with [Simian Virus 40]. Full crystallographic information is available from OCA.

Reference

Structure of the replicative helicase of the oncoprotein SV40 large tumour antigen., Li D, Zhao R, Lilyestrom W, Gai D, Zhang R, DeCaprio JA, Fanning E, Jochimiak A, Szakonyi G, Chen XS, Nature. 2003 May 29;423(6939):512-8. PMID:12774115

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