A new approach combining LC-MS and multivariate statistical analysis for revealing changes in histone modification levels.

While acting upon chromatin compaction, histone post-translational modifications (PTMs) are involved in modulating gene expression through histone-DNA affinity and protein-protein interactions. These dynamic and environment-sensitive modifications are constitutive of the histone code that reflects the transient transcriptional state of the chromatin. Here we describe a global screening approach for revealing epigenetic disruption at the histone level.

Dissection of the structural organization of the aminoacyl-tRNA synthetase complex.

The spatio-temporal organization of proteins within the cytoplasm of eukaryotic cells rests in part on the assembly of stable and transient multiprotein complexes. Here we examined the assembly of the multiaminoacyl-tRNA synthetase complex (MARS) in human cells. This complex contains nine aminoacyl-tRNA synthetases and three auxiliary proteins and is a hallmark of metazoan species.

A novel mutant of the Sup35 protein of Saccharomyces cerevisiae defective in translation termination and in GTPase activity still supports cell viability.

Background: When a stop codon is located in the ribosomal A-site, the termination complex promotes release of the polypeptide and dissociation of the 80S ribosome. In eukaryotes two proteins eRF1 and eRF3 play a crucial function in the termination process. The essential GTPase Sup35p, the eRF3 release factor of Saccharomyces cerevisiae is highly conserved.

Cadmium response and redoxin targets in Chlamydomonas reinhardtii: a proteomic approach.

A proteomic approach including two-dimensional electrophoresis and MALDI-TOF analysis has been developed to identify the soluble proteins of the unicellular photosynthetic algae Chlamydomonas reinhardtii. We first described the partial 2D-picture of soluble proteome obtained from whole cells grown on acetate. Then we studied the effects of the exposure of these cells to 150 muM cadmium (Cd).

MafA transcription factor is phosphorylated by p38 MAP kinase.

Basic-leucine zipper transcription factors of the Maf family are key regulators of various developmental and differentiation processes. We previously reported that the phosphorylation status of MafA is a critical determinant of its biological functions. Using Western blot and mass spectrometry analysis, we now show that MafA is phosphorylated by p38 MAP kinase and identify three phosphoacceptor sites: threonine 113 and threonine 57, evolutionarily conserved residues located in the transcription activating domain, and serine 272.

Is 2-phosphoglycerate-dependent automodification of bacterial enolases implicated in their export?

We observed that in vivo and in vitro a small fraction of the glycolytic enzyme enolase became covalently modified by its substrate 2-phosphoglycerate (2-PG). In modified Escherichia coli enolase, 2-PG was bound to Lys341, which is located in the active site. An identical reversible modification was observed with other bacterial enolases, but also with enolase from Saccharomyces cerevisiae and rabbit muscle.

A single mutation that causes phosphatidylglycerol deficiency impairs synthesis of photosystem II cores in Chlamydomonas reinhardtii.

Two mutants of Chlamydomonas reinhardtii, mf1 and mf2, characterized by a marked reduction in their phosphatidylglycerol content together with a complete loss in its Delta3-trans hexadecenoic acid-containing form, also lost photosystem II (PSII) activity. Genetic analysis of crosses between mf2 and wild-type strains shows a strict cosegregation of the PSII and lipid deficiencies, while phenotypic analysis of phototrophic revertant strains suggests that one single nuclear mutation is responsible for the pleiotropic phenotype of the mutants. The nearly complete absence of PSII core is due to a severely decreased synthesis of two subunits, D1 and apoCP47, which is not due to a decrease in translation initiation.

Transmembrane modulator-dependent bacterial tyrosine kinase activates UDP-glucose dehydrogenases.

Protein-tyrosine kinases regulating bacterial exopolysaccharide synthesis autophosphorylate on tyrosines located in a conserved C-terminal region. So far no other substrates have been identified for these kinases. Here we demonstrate that Bacillus subtilis YwqD not only autophosphorylates at Tyr-228, but that it also phosphorylates the two UDP-glucose dehydrogenases (UDP-glucose DHs) YwqF and TuaD at a tyrosine residue.