Poster abstracts

Poster number 47 submitted by Anna Griffis

Minding the GAP in Arabidopsis Gametogenesis

Anna H.N. Griffis (Department of Molecular Genetics and Center for RNA Biology, The Ohio State University), Joanna Boruc (Department of Molecular Genetics, The Ohio State University), Iris Meier (Department of Molecular Genetics and Center for RNA Biology, The Ohio State University)

Abstract:
RanGAP is the activating protein for the small GTPase Ran, and is involved in nucleocytoplasmic transport and mitotic cell division across kingdoms. Arabidopsis has two RanGAP genes, RANGAP1 and RANGAP2, which have partially redundant function. We recently discovered that a RANGAP1 RANGAP2 double null mutant is female gametophyte lethal, arresting after the first mitotic division following meiosis. During open mitosis, RANGAP1 is targeted by a plant-specific domain to sites important for mitosis/cytokinesis, and depletion of RANGAP1 transcripts leads to cell wall placement defects. A mutant combining a RANGAP1 null allele with severely decreased RANGAP2 expression has severe defects in sporophyte development, but no apparent defect in protein nuclear import. We hypothesize that these data reveal novel, plant-specific roles for RanGAP. To determine whether RanGAP’s canonical GTPase activation (GAP) activity and/or its unique mitotic localization are required for wildtype RanGAP function, we have generated point mutations and deletions in RANGAP1 that disrupt its GAP activity, subcellular targeting, or both. We then determine whether these mutant proteins rescue female gametohpyte lethality and sporophyte development. Additionally, we investigate the role of plant RanGAP in nucleocytoplasmic trafficking of RNAs and large protein complexes.

Keywords: RanGAP, Ran, Arabidopsis