| Abstract Detail
Organelle Biology Asakura, Yukari [1], Bayraktar, Omar [1], Watkins, Kenneth [1], Barkan, Alice [1]. CFM3, a CRM domain protein related to the chloroplast splicing factor CRS1, functions dually in chloroplast group II intron splicing and mitochondrial gene expression. The CRM domain is an RNA binding domain that was originally recognized in three group II intron splicing factors in maize chloroplasts (CRS1, CAF1, and CAF2) (1,2). The Arabidopsis and rice genomes encode 16 and 14 CRM-domain proteins, respectively, but these are largely uncharacterized (3). CFM3 (CRM Family Member 3) is closely related to CRS1 and harbors three CRM domains. GFP-fusion protein and immunoblot analyses showed that maize CFM3 is localized to both the chloroplast and mitochondrion. To identify native RNA ligands of CFM3, we used the RIP-chip assay (4). Anti-CFM3 antibodies co-immunopreciptated several group II intron RNAs from chloroplast extract; the set of coimmunoprecipitated introns overlaps with, but is distinct from the intron sets that are associated with CRS1, CAF1, CAF2, and with another CRM protein called CFM2. To explore the functions of CFM3, we analyzed Arabidopsis T-DNA insertion alleles: Atcfm3-1 conditions an embryo lethal phenotype whereas Atcfm3-4 is a weak allele that conditions a small seedling phenotype. The Atcfm3-4 mutant is impaired in the splicing of the chloroplast ndhB intron and in 5’ maturation of mitochondrial rrn18. AtCFM4 is a co-ortholog of AtCFM3 that is found in Arabidopsis but not in rice. Homozygous Atcfm3-4/Atcfm4-2 double knockouts are embryo lethal, suggesting that AtCFM3 and AtCFM4 act redundantly to promote the expression of one or more organellar gene that is essential for embryogenesis. These findings add to the list of group II intron splicing factors in chloroplasts, and extend the functions established for CRM proteins to ribosomal maturation in mitochondria. 1. Till et al., 2001, RNA. 2. Ostheimer et al., 2003, EMBO J. 3. Barkan et al., 2007 RNA.4. Schmitz-Linneweber et al., 2005, Plant Cell.
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1 - Institute of Molecular Biology, University of Oregon, Eugene, Oregon, 97403, USA
Keywords:
Chloroplast
intron splicing
group II intron
RNA-binding protein
mitochondria.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P18022
Abstract ID:1298 |
