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An HflX-type GTPase from Sulfolobus solfataricus binds to the 50S ribosomal subunit in all nucleotide-bound states

Blombach, F. and Launay, H. and Zorraquino, V. and Swarts, D.C. and Cabrita, L.D. and Benelli, D. and Christodoulou, John and Londei, P. and van der Oost, J. (2011) An HflX-type GTPase from Sulfolobus solfataricus binds to the 50S ribosomal subunit in all nucleotide-bound states. Journal of Bacteriology 193 (11), pp. 2861-2867. ISSN 0021-9193.

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Official URL: http://dx.doi.org/10.1128/JB.01552-10

Abstract

HflX GTPases are found in all three domains of life, Bacteria, Archaea, and Eukaryotes. HflX from Escherichia coli has been shown to bind to the 50S ribosomal subunit in a nucleotide-dependent manner and this interaction strongly stimulates its GTPase activity. We recently determined the structure of an HflX ortholog from the archaeon Sulfolobus solfataricus (Sso HflX). It revealed the presence of a novel HflX-domain that might function in RNA-binding and is linked to a canonical G-domain. This domain arrangement is common to all archaeal, bacterial, and eukaryotic HflX GTPases. This paper shows that the archaeal Sso HflX, like its bacterial orthologs, binds to the 50S ribosomal subunit. This interaction does not depend on the presence of guanine nucleotides. The HflX-domain is sufficient for ribosome interaction. Binding appears to be restricted to free 50S ribosomal subunits and does not occur with 70S ribosomes engaged in translation. The fingerprint (1)H-(15)N NMR spectrum of Sso HflX reveals a large number of well-resolved resonances that are broadened upon binding to the 50S ribosomal subunit. The GTPase activity of Sso HflX is stimulated by crude fractions of 50S ribosomal subunits, but this effect is lost with further high-salt purification of the 50S ribosomal subunits, suggesting that the stimulation depends on an extrinsic factor bound to the 50S ribosomal subunit. Our results reveal common properties, but also marked differences between archaeal and bacterial HflX.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 24 May 2011 09:59
Last Modified: 17 Apr 2013 12:20
URI: http://eprints.bbk.ac.uk/id/eprint/3325

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