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Journal of Virology, May 2007, p. 5238-5245, Vol. 81, No. 10
0022-538X/07/$08.00+0 doi:10.1128/JVI.02680-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Daniël Duijsings,1,
Kjerstin H. W. Lanke,1
Willem J. G. Melchers,1
Catherine L. Jackson,2 and
Frank J. M. van Kuppeveld1*
Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands,1 Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 208922
Received 5 December 2006/ Accepted 19 February 2007
The 3A protein of coxsackievirus B3 (CVB3), a small membrane protein that forms homodimers, inhibits endoplasmic reticulum-to-Golgi complex transport. Recently, we described the underlying mechanism by showing that the CVB3 3A protein binds to and inhibits the function of GBF1, a guanine nucleotide exchange factor for ADP-ribosylation factor 1 (Arf1), thereby interfering with Arf1-mediated COP-I recruitment. This study was undertaken to gain more insight into the molecular determinants underlying the interaction between 3A and GBF1. Here we show that 3A mutants that have lost the ability to dimerize are no longer able to bind to GBF1 and trap it on membranes. Moreover, we identify a conserved region in the N terminus of 3A that is crucial for GBF1 binding but not for 3A dimerization. Analysis of the binding domain in GBF1 showed that the extreme N terminus, the dimerization/cyclophilin binding domain, and the homology upstream of Sec7 domain are required for the interaction with 3A. In contrast to that of full-length GBF1, overexpression of a GBF1 mutant lacking its extreme N terminus failed to rescue the effects of 3A. Together, these data provide insight into the molecular requirements of the interaction between 3A and GBF1.
Published ahead of print on 28 February 2007.
E.W. and D.D. contributed equally to this work.
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