: Tubulin dimer binding proteins

International audienceMicrotubules play an essential role in eukaryotic cells, where they perform a wide variety of functions. In this paper, we describe the characterization of proteins associated to tubulin dimer in its native form, using affinity chromatography and mass spectrometry. We used an immunoaffinity column with coupled-monoclonal antibody directed against the alpha-tubulin C-terminus. Tubulin was first loaded onto the column, then interphase and mitotic cell lysates were chromatographed. Tubulin-binding proteins were eluted using a peptide mimicking the alpha-tubulin C-terminus. Elution fractions were analyzed by SDS-PAGE, and a total of 14 proteins were identified with high confidence by mass spectrometry. These proteins could be grouped in four classes: known tubulin-binding proteins, one microtubule-associated protein, heat shock proteins, and proteins that were not shown previously to bind tubulin dimer or microtubules

GRASS : flame retardant artificial turf : safe and sustainable

Artificial grass is mainly composed of organic polymers with a consequent potential fire hazard. However, the behaviour of artificial grass in case of fire has been poorly studied and is thus misunderstood. The GRASS project has two objectives: informing the public that natural turf has a different fire behaviour than artificial turf and improving fire behaviour of artificial turf by developing innovative, eco-friendly and industrially applicable processes. In the project, constant consultations take place with a resonance group of stake holders represented by producers, installers, sports organisations, governments and end users. The involvement of the resonance group is sufficient guarantee that the new processes emanating from this project will be acceptable for all actors involved in the artificial turf sector (from production and end usage to recycling) and that they will be put into practice

Contribution of infill materials to the fire behavior of artificial grass

Artificial grass is mainly composed of organic polymers with a consequent potential fire hazard. However, the behavior of artificial grass in case of fire has been poorly studied and is thus misunderstood. The purpose of this study is thus to have a better understanding of the contribution of the different components of the artificial turf in the fire performances. In this work, the influence of the nature of the infill is more specifically investigated

PscF is a major component of the Pseudomonas aeruginosa type III secretion needle.

International audiencePseudomonas aeruginosa, a Gram-negative opportunistic pathogen, translocates exoenzymes (Exo) directly into the eukaryotic cell cytoplasm. This is accomplished by a type III secretion/translocation machinery. Here, we show that the P. aeruginosa type III secretory needle structure is composed essentially of PscF, a protein required for secretion and P. aeruginosa cytotoxicity. Partially purified needles, detached from the bacterial surface, are 60-80 nm in length and 7 nm in width, resembling needles from Yersinia spp.. YscF of Yersinia enterocolitica was able to functionally complement the pscF deletion, but required 11 P. aeruginosa-specific amino acids at the N-terminus for its function

Mutual regulation of Crl and Fur in Escherichia coli W3110.

The small regulatory protein Crl controls the expression of curli. Recently we have shown that Crl interacts directly with one of the most global regulators of Escherichia coli, the stress-related sigma factor RpoS, suggesting a more global role for Crl. We show here by a proteomics analysis that the expression of at least nine cellular proteins was considerably modified when Crl was overexpressed. We assessed the part of transcriptional and post-transcriptional regulation for five of these genes. The results showed that Crl regulates the expression of another global regulator, the central regulator of iron homeostasis, Fur. A molecular analysis revealed that Crl and Fur affect their own and each other's expression. We provide physical evidence for the binding of Fur to the crl and fur promoter regions. Crl modulated the affinity of Fur at the fur promoter but not at the crl promoter. The triad RpoS-Crl-Fur may thus represent the centerpiece of a global regulatory system of response to different stresses

Towards a human repertoire of monocytic lysosomal proteins

International audienceThe lysosomal compartment of human monocytic cells has never been investigated by a proteomic approach. By a combination of one‐dimensional (1‐D) and two‐dimensional (2‐D) gel electrophoresis, protein identification by N‐terminal sequencing, matrix assisted laser desorption/ionization‐mass spectrometry (MALDI‐MS) peptide mass fingerprinting and tandem mass spectrometry (MS/MS) peptide sequence analysis, we initiated an exhaustive study of the human lyososomal proteome, which aims at establishing a 2‐D reference map of human soluble lyososomal proteins. Human monocytic U937 cells were induced to secrete lysosomal soluble hydrolases by addition of NH$_4$Cl in the culture medium. Since lysosomal soluble proteins are characterized by the presence of mannose‐6‐phosphate, they were purified on an affinity support bearing mannose‐6‐phosphate receptor. Analysis of the purified fraction led to the preliminary identification of fifteen proteins, among which twelve are well‐known lysosomal hydrolases, one is assumed to be lysosomal on the basis of sequence homology to cysteine proteinases of the papain family, and two (leukocystatin and the human cellular repressor of E1A‐stimulated genes) are described here for the first time as mannose‐6‐phosphate‐containing proteins

High-density rafts preferentially host the complement activator measles virus F glycoprotein but not the regulators of complement activation

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Identification of Pyrene-Induced Proteins in Mycobacterium sp. Strain 6PY1: Evidence for Two Ring-Hydroxylating Dioxygenases

In this study, the enzymes involved in polycyclic aromatic hydrocarbon (PAH) degradation were investigated in the pyrene-degrading Mycobacterium sp. strain 6PY1. [(14)C]pyrene mineralization experiments showed that bacteria grown with either pyrene or phenanthrene produced high levels of pyrene-catabolic activity but that acetate-grown cells had no activity. As a means of identifying specific catabolic enzymes, protein extracts from bacteria grown on pyrene or on other carbon sources were analyzed by two-dimensional gel electrophoresis. Pyrene-induced proteins were tentatively identified by peptide sequence analysis. Half of them resembled enzymes known to be involved in phenanthrene degradation, with closest similarity to the corresponding enzymes from Nocardioides sp. strain KP7. The genes encoding the terminal components of two distinct ring-hydroxylating dioxygenases were cloned. Sequence analysis revealed that the two enzymes, designated Pdo1 and Pdo2, belong to a subfamily of dioxygenases found exclusively in gram-positive bacteria. When overproduced in Escherichia coli, Pdo1 and Pdo2 showed distinctive selectivities towards PAH substrates, with the former enzyme catalyzing the dihydroxylation of both pyrene and phenanthrene and the latter preferentially oxidizing phenanthrene. The catalytic activity of the Pdo2 enzyme was dramatically enhanced when electron carrier proteins of the phenanthrene dioxygenase from strain KP7 were coexpressed in recombinant cells. The Pdo2 enzyme was purified as a brown protein consisting of two types of subunits with M(r)s of about 52,000 and 20,000. Immunoblot analysis of cell extracts from strain 6PY1 revealed that Pdo1 was present in cells grown on benzoate, phenanthrene, or pyrene and absent in acetate-grown cells. In contrast, Pdo2 could be detected only in PAH-grown cells. These results indicated that the two enzymes were differentially regulated depending on the carbon source used for growth

New Subunits NDH-M, -N, and -O, Encoded by Nuclear Genes, Are Essential for Plastid Ndh Complex Functioning in Higher Plants

In higher plants, the Ndh complex reduces plastoquinones and is involved in cyclic electron flow around photosystem I, supplying extra-ATP for photosynthesis, particularly under environmental stress conditions. Based on plastid genome sequences, the Ndh complex would contain 11 subunits (NDH-A to -K), but homologies with bacterial complex indicate the probable existence of additional subunits. To identify missing subunits, tobacco (Nicotiana tabacum) NDH-H was His tagged at its N terminus using plastid transformation. A functional Ndh subcomplex was purified by Ni(2+) affinity chromatography and its subunit composition analyzed by mass spectrometry. Five plastid encoded subunits (NDH-A, -H, -I, -J, and -K) were identified as well as three new subunits (NDH-M, -N, and -O) homologous to cyanobacterial and higher plant proteins. Arabidopsis thaliana mutants missing one of these new subunits lack a functional Ndh complex, and NDH-M and NDH-N are not detected in a tobacco transformant lacking the Ndh complex. We discuss the involvement of these three nuclear-encoded subunits in the functional integrity of the plastidial complex