Arabidopsis NAP-related proteins (NRPs) contribute to the coordination of plant growth, developmental rate, and age-related pathogen resistance under short days.

Plant nucleosome assembly protein-related proteins (NRPs) are histone chaperons involved in nucleosome turnover. Despite this basic cellular function, the Arabidopsis nrp1-1 nrp2-1 knock out mutant has been reported to exhibit only mild seedling root phenotypes and to significantly affect the expression of only few hundred genes Zhu et al. (2006).

In silico identification and experimental validation of amino acid motifs required for the Rho-of-plants GTPase-mediated activation of receptor-like cytoplasmic kinases.

Several amino acid motifs required for Rop-dependent activity were found to form a common surface on RLCKVI_A kinases. This indicates a unique mechanism for Rho-type GTPase-mediated kinase activation in plants. Rho-of-plants (Rop) G-proteins are implicated in the regulation of various cellular processes, including cell growth, cell polarity, hormonal and pathogen responses.

The phosphomimetic mutation of syndecan-4 binds and inhibits Tiam1 modulating Rac1 activity in PDZ interaction-dependent manner.

The small GTPases of the Rho family comprising RhoA, Rac1 and Cdc42 function as molecular switches controlling several essential biochemical pathways in eukaryotic cells. Their activity is cycling between an active GTP-bound and an inactive GDP-bound conformation. The exchange of GDP to GTP is catalyzed by guanine nucleotide exchange factors (GEFs).

Identification of genes preferentially expressed in wheat egg cells and zygotes.

KEY MESSAGE : Wheat genes differentially expressed in the egg cell before and after fertilization were identified. The data support zygotic gene activation before the first cell division in wheat. To have an insight into fertilization-induced gene expression, cDNA libraries have been prepared from isolated wheat egg cells and one-celled zygotes.

Barley ROP binding kinase1 is involved in microtubule organization and in basal penetration resistance to the barley powdery mildew fungus.

Certain plant receptor-like cytoplasmic kinases were reported to interact with small monomeric G-proteins of the RHO of plant (ROP; also called RAC) family in planta and to be activated by this interaction in vitro. We identified a barley (Hordeum vulgare) partial cDNA of a ROP binding protein kinase (HvRBK1) in yeast (Saccharomyces cerevisiae) two-hybrid screenings with barley HvROP bait proteins. Protein interaction of the constitutively activated (CA) barley HvROPs CA HvRACB and CA HvRAC1 with full-length HvRBK1 was verified in yeast and in planta.

The histone phosphatase inhibitory property of plant nucleosome assembly protein-related proteins (NRPs).

SET/I(2)(PP2A), a member of the family of nucleosome assembly proteins (NAPs), has been previously described as a multifunctional protein inhibiting protein phosphatase 2A (PP2A)-mediated histone H3((pSer10)) dephosphorylation during the heat shock response in animal cells. In the present work we demonstrate that its plant orthologs, designated as NAP-related proteins (NRPs), have a similar in vitro biochemical activity and interact with PP2A and histone H3((pSer10))in vivo. Although heat shock gene promoters were found to be associated with histone H3((pSer10))-marked chromatin following a high temperature treatment, heat shock gene expression was not affected in NRP-deficient mutant Arabidopsis thaliana (L.

The phosphomimetic mutation of an evolutionarily conserved serine residue affects the signaling properties of Rho of plants (ROPs).

Plant ROP (Rho of plants) proteins form a unique subgroup within the family of Rho-type small G-proteins of eukaryotes. In this paper we demonstrate that the phosphomimetic mutation of a serine residue conserved in all Rho proteins affects the signaling properties of plant ROPs. We found that the S74E mutation in Medicago ROP6 and Arabidopsis ROP4 prevented the binding of these proteins to their plant-specific upstream activator the plant-specific ROP nucleotide exchanger (PRONE)-domain-containing RopGEF (guanine nucleotide exchange factor) protein and abolished the PRONE-mediated nucleotide exchange reaction in vitro.

Characterization of three Rop GTPase genes of alfalfa (Medicago sativa L.).

Three cDNA clones coding for Medicago sativa Rop GTPases have been isolated. The represented genes could be assigned to various linkage groups by genetic mapping. They were expressed in all investigated plant organs, although at different level.

Nitric oxide is required for, and promotes auxin-mediated activation of, cell division and embryogenic cell formation but does not influence cell cycle progression in alfalfa cell cultures.

It is now well established that nitric oxide (NO) serves as a signaling molecule in plant cells. In this paper experimental data are presented which indicate that NO can stimulate the activation of cell division and embryogenic cell formation in leaf protoplast-derived cells of alfalfa in the presence of auxin. It was found that various NO-releasing compounds promoted auxin-dependent division (as shown by incorporation of bromodeoxyuridine) of leaf protoplast-derived alfalfa cells.