Divergent contribution of the MVA and MEP pathways to the formation of polyprenols and dolichols in Arabidopsis.

Isoprenoids, including dolichols (Dols) and polyprenols (Prens), are ubiquitous components of eukaryotic cells. In plant cells, there are two pathways that produce precursors utilized for isoprenoid biosynthesis: the mevalonate (MVA) pathway and the methylerythritol phosphate (MEP) pathway. In this work, the contribution of these two pathways to the biosynthesis of Prens and Dols was addressed using an in planta experimental model.

Impact of C-terminal truncations in the Arabidopsis Rab escort protein (REP) on REP-Rab interaction and plant fertility.

Lipid anchors are common post-translational modifications for proteins engaged in signaling and vesicular transport in eukaryotic cells. Rab proteins are geranylgeranylated at their C-termini, a modification which is important for their stable binding to lipid bilayers. The Rab escort protein (REP) is an accessory protein of the Rab geranylgeranyl transferase (RGT) complex and it is obligatory for Rab prenylation.

[The functions of Rab proteins in plants - from cellular to organismal level].

Rab proteins are necessary for membrane fusion and fission and as such are key regulators of intracellular transport in eukaryotic cells. They also control other aspects of cell functioning, including the cytoskeleton rearrangements, determination of cell polarity or signal transduction. Rab proteins exert their control both indirectly, because they decide whether all necessary proteins and other cargo reach their correct destinations in the cell, and directly, through interactions of their active forms with effector proteins.

Global pentapeptide statistics are far away from expected distributions.

The relationships between polypeptide composition, sequence, structure and function have been puzzling biologists ever since first protein sequences were determined. Here, we study the statistics of occurrence of all possible pentapeptide sequences in known proteins. To compensate for the non-uniform distribution of individual amino acid residues in protein sequences, we investigate separately all possible permutations of every given amino acid composition.

Cell-to-Cell Communication Circuits: Quantitative Analysis of Synthetic Logic Gates.

One of the goals in the field of synthetic biology is the construction of cellular computation devices that could function in a manner similar to electronic circuits. To this end, attempts are made to create biological systems that function as logic gates. In this work we present a theoretical quantitative analysis of a synthetic cellular logic-gates system, which has been implemented in cells of the yeast Saccharomyces cerevisiae (Regot et al.

LTR retrotransposons in fungi.

Transposable elements with long terminal direct repeats (LTR TEs) are one of the best studied groups of mobile elements. They are ubiquitous elements present in almost all eukaryotic genomes. Their number and state of conservation can be a highlight of genome dynamics.

[The p24 family proteins--regulators of vesicular trafficking].

The trafficking of proteins in the secretory pathway is mediated by vesicles. Proteins of the p24 family are present on the membranes of secretory pathway organelles (ER, Golgi, COPI and COPII vesicles). Evidence exists showing that p24 proteins play a role in the development of Alzheimer disease, making them an interesting research subject.

Mutations in the Saccharomyces cerevisiae vacuolar fusion proteins Ccz1, Mon1 and Ypt7 cause defects in cell cycle progression in a num1Delta background.

The proteins Ccz1 and Mon1 are known to function together with the Rab-GTPase Ypt7 in membrane fusion reactions at the yeast vacuole. In a genome-wide analysis they have also been found to interact genetically with the nuclear-migration protein Num1. In this study we analyze these synthetic effects and we show that the mutants ccz1Delta num1Delta, mon1Delta num1Delta and ypt7Delta num1Delta exhibit severe defects in cell cycle progression.

The Saccharomyces cerevisiae protein Ccz1p interacts with components of the endosomal fusion machinery.

The yeast protein Ccz1p is necessary for vacuolar protein trafficking and biogenesis. In a complex with Mon1p, it mediates fusion of transport intermediates with the vacuole membrane by activating the small GTPase Ypt7p. Additionally, genetic data suggest a role of Ccz1p in earlier transport steps, in the Golgi.

The yeast protein sorting pathway as an experimental model for lysosomal trafficking.

Lysosomes are conserved organelles that are present in all eukaryotic cells. They are part of a complicated network of intracellular trafficking routes - the lysosomal transport system. Lysosomes are necessary for the maintenance of cellular homeostasis and for many specialized functions, including the activity of many components of the mammalian immune system.

The CHiPS Domain--ancient traces for the Hermansky-Pudlak syndrome.

Hermansky-Pudlak syndrome (HPS) is a rare disorder caused by malfunctions of lysosomes and specialized lysosome-related organelles, resulting primarily in oculocutaneous albinism and bleeding diathesis. The majority of the HPS genes have been described as novel, but herein we report the identification of a conserved protein family which includes human HPS4, as well as distant homologs for other HPS genes. Our results suggest that the cellular machinery involved in the HPS syndrome is ancient.