User:Udayan Shevade/Sandbox1
From Proteopedia
Contents |
SV40 Large T-Antigen
Introduction
The SV40 large T-antigen is a multifunctional regulatory protein encoded by Simian Virus 40, belonging to the AAA+ family of helicases [1]. It is responsible for initiation of replication, regulation of transcription and alteration of the host cell cycle to promote its infectivity.
Structure
T-antigen consists of an N-terminal J domain, a central origin-binding domain, and a C-terminal helicase domain [1].
The Origin Binding Domain
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The central obd monomer consists of five anti-parallel beta sheets flanked on both sides by pairs of alpha helices. These molecules arrange tightly into a hexameric left-handed spiral, with 6 obd's per turn. The conformation creates a central channel 60 Angstrom wide, large enough for dsDNA, and is both hydrophobic and highly positively charged [1]. Side-side interaction is crucial in hexamerization, for which residues are crucial. Along the inner surface of the channel, residues implicated in DNA binding are Asn 153, Arg 154, Thr 155 from the A motif; His 203, Arg 204 from the B2 motif; as well as His 201 and Arg 202 [1].
