eIF4A RNA Helicase Associates with Cyclin-Dependent Protein Kinase A in Proliferating Cells and Is Modulated by Phosphorylation.

Eukaryotic initiation factor 4A (eIF4A) is a highly conserved RNA-stimulated ATPase and helicase involved in the initiation of messenger RNA translation. Previously, we found that eIF4A interacts with cyclin-dependent kinase A (CDKA), the plant ortholog of mammalian CDK1. Here, we show that this interaction occurs only in proliferating cells where the two proteins coassociate with 5'-cap-binding protein complexes, eIF4F or the plant-specific eIFiso4F.

The RNA helicase, eIF4A-1, is required for ovule development and cell size homeostasis in Arabidopsis.

eIF4A is a highly conserved RNA-stimulated ATPase and helicase involved in the initiation of mRNA translation. The Arabidopsis genome encodes two isoforms, one of which (eIF4A-1) is required for the coordination between cell cycle progression and cell size. A T-DNA mutant eif4a1 line, with reduced eIF4A protein levels, displays slow growth, reduced lateral root formation, delayed flowering and abnormal ovule development.

The inhibitor of wax 1 locus (Iw1) prevents formation of β- and OH-β-diketones in wheat cuticular waxes and maps to a sub-cM interval on chromosome arm 2BS.

Glaucousness is described as the scattering effect of visible light from wax deposited on the cuticle of plant aerial organs. In wheat, two dominant genes lead to non-glaucous phenotypes: Inhibitor of wax 1 (Iw1) and Iw2. The molecular mechanisms and the exact extent (beyond visual assessment) by which these genes affect the composition and quantity of cuticular wax is unclear.

The Arabidopsis RNA-directed DNA methylation argonautes functionally diverge based on their expression and interaction with target loci.

Argonaute (AGO) effectors of RNA silencing bind small RNA (sRNA) molecules and mediate mRNA cleavage, translational repression, or epigenetic DNA modification. In many organisms, these targeting mechanisms are devolved to different products of AGO multigene families. To investigate the basis of AGO functional diversification, we characterized three closely related Arabidopsis thaliana AGOs (AGO4, AGO6, and AGO9) implicated in RNA-directed DNA methylation.

Selective recruitment of proteins to 5' cap complexes during the growth cycle in Arabidopsis.

Translation of most mRNAs is performed in a cap-dependent manner, requiring a protein complex, the cap complex, to regulate the accessibility of the message to the 40S ribosome. The cap complex initiates protein translation by binding to the 5' cap of an mRNA and recruiting ribosomes to begin translation. Compared to animals and yeast, there are significant plant-specific differences in the regulation of cap-dependent mRNA translation, but these are poorly understood.

Modulation of the cellulose content of tuber cell walls by antisense expression of different potato (Solanum tuberosum L.) CesA clones.

Four potato cellulose synthase (CesA) homologs (StCesA1, 2, 3 and 4) were isolated by screening a cDNA library made from developing tubers. Based on sequence comparisons and the fact that all four potato cDNAs were isolated from this single cDNA-library, all four StCesA clones are likely to play a role in primary cell wall biosynthesis. Several constructs were generated to modulate cellulose levels in potato plants in which the granule-bound starch synthase promoter was used to target the modification to the tubers.

In muro fragmentation of the rhamnogalacturonan I backbone in potato (Solanum tuberosum L.) results in a reduction and altered location of the galactan and arabinan side-chains and abnormal periderm development.

Rhamnogalacturonan (RG) I is a branched pectic polysaccharide in plant cell walls. Rhamnogalacturonan lyase (eRGL) from Aspergillus aculeatus is able to cleave the RG I backbone at specific sites. Transgenic potato (Solanum tuberosum L.

Direct interference with rhamnogalacturonan I biosynthesis in Golgi vesicles.

Pectin is a class of complex cell wall polysaccharides with multiple roles during cell development. Assigning specific functions to particular polysaccharides is in its infancy, in part, because of the limited number of mutants and transformants available with modified pectic polymers in their walls. Pectins are also important polymers with diverse applications in the food and pharmaceutical industries, which would benefit from technology for producing pectins with specific functional properties.