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Cell Cycle. 2013 Feb 1;12(3):463-72. doi: 10.4161/cc.23367. Epub 2013 Jan 16.

Eukaryotic GPN-loop GTPases paralogs use a dimeric assembly reminiscent of archeal GPN.

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  • 1CEA, iBEB, Service de Biochimie et Toxicologie Nucléaire/LBSP, Bagnols-sur-Cèze, France.


GTPases are molecular switches that regulate a wide-range of cellular processes. The GPN-loop GTPase (GPN) is a sub-family of P-loop NTPase that evolved from a single gene copy in archaea to triplicate paralog genes in eukaryotes, each having a non-redundant essential function in cell. In Saccharomyces cerevisiae, yGPN1 and yGPN2 are involved in sister chromatid cohesion mechanism, whereas nothing is known regarding yGPN3 function. Previous high-throughput experiments suggested that GPN paralogs interaction may occur. In this work, GPN|GPN contact was analyzed in details using TAP-Tag approach, yeast two-hybrid assay, in silico energy computation and site-directed mutagenesis of a conserved Glu residue located at the center of the interaction interface. It is demonstrated that this residue is essential for cell viability. A chromatid cohesion assay revealed that, like yGPN1 and yGPN2, yGPN3 also plays a role in sister chromatid cohesion. These results suggest that all three GPN proteins act at the molecular level in sister chromatid cohesion mechanism as a GPN|GPN complex reminiscent of the homodimeric structure of PAB0955, an archaeal member of GPN-loop GTPase.


GPN-loop-GTPase; P-loop NTPase; chromatid cohesion; heterodimer; paralogous interactions

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