The β-lactam antibiotics mimic the d-alanyl⁴-d-alanine⁵ extremity of peptidoglycan precursors and act as "suicide" substrates dd-transpeptidases that catalyze last cross-linking step synthesis. We have previously shown bypass by ld-transpeptidase <i>Enterococcus faecium</i> (Ldt_fm) leads to high level resistance ampicillin. Ldt_fm is specific for l-lysyl³-d-alanine⁴ bond containing a tetrapeptide stem lacking...

As essential components of the eukaryotic cytoskeleton, microtubules fulfill a variety functions that can be temporally and spatially controlled by tubulin posttranslational modifications. Tubulin glycylation has so far been mostly found on motile cilia flagella, where it is involved in stabilization axoneme. In contrast, barely anything known about role primary because limitations detecting this modification these organelles. We thus developed novel glycylation-specific antibodies with...

To perform their multiple functions, cilia and flagella are precisely positioned at the cell surface by mechanisms that remain poorly understood. The protist Trypanosoma brucei possesses a single flagellum adheres to body where specific cytoskeletal structure is localised, attachment zone (FAZ). Trypanosomes build new whose distal tip connected side of old discrete structure, connector. During this process, basal migrates towards posterior end cell. We show separate inhibition assembly,...

Cylindrospermopsis raciborskii is a toxic bloom-forming cyanobacterium that occurs at tropical and temperate latitudes. Despite several reports from Africa, no data were previously available about its dynamics or potential there. We therefore carried out 1-year survey of the C. in main water reservoir Senegal, Lake Guiers. never formed bloom this lake during period studied, but was dominant dry season. The only observed species diatom, Fragilaria sp., which displayed seasonal pattern...

Antibiotics of the β-lactam (penicillin) family inactivate target enzymes called D,D-transpeptidases or penicillin-binding proteins (PBPs) that catalyze last cross-linking step peptidoglycan synthesis. The resulting net-like macromolecule is essential component bacterial cell walls sustains osmotic pressure cytoplasm. In Escherichia coli , bypass PBPs by YcbB L,D-transpeptidase leads to resistance these drugs. We developed a new method based on heavy isotope labeling and mass spectrometry...

The Met residue oxidation has been studied for decades. Although many efforts have made on the identification of free radicals, some doubts remain about their final fates, i.e., nature stable products. photosensitized processes two peptides, methionyl lysine (Met-Lys) and lysyl methionine (Lys-Met), were investigated using 3-carboxybenzophenone (3CB) as a sensitizer. Therefore, not only transients characterized but also products (by high-performance liquid chromatography mass spectrometry)...

Enkephalins are bioactive pentapeptides (Tyr-Gly-Gly-Phe-Leu (Leu-enk) and Tyr-Gly-Gly-Phe-Met (Met-enk)) produced while an organism is under mental and/or physical stress. In the course of their biological action they exposed to reactive oxygen nitrogen species. We have reinvestigated reactions •OH radicals toward these peptides in order elucidate oxidation mechanisms final products. Nanosecond pulse radiolysis was used obtain spectra reaction intermediates kinetics. Additional insight into...

Treatment of rabbit sarcoplasmic reticulum Ca2+-ATPase with a variety proteases, including elastase, proteinase K, and endoproteinases Asp-N Glu-C, results in accumulation soluble fragments starting close to the ATPase phosphorylation site Asp351 ending Lys605-Arg615 region, well before conserved sequences generally described as constituting “hinge” region this P-type (residues 670–760). These fragments, designated p29/30, presumably originate from relatively compact domain cytoplasmic head...

Abstract Summary: Since the middle of 90s, mass spectrometry has evolved into an almost indispensable tool in structural studies on ever-growing variety (bio-)polymers, which proteins, sugars and nucleic acids are most prominent. first public release massXpert, advances have motivated continuous thorough maintenance that software, form two full software rewrites, culminating with massXpert 2, we describe this report. We shall profound changes were performed so as to keep up technical since a...

A component of the stator yeast ATP synthase (subunit 4 or b) showed many cross-linked products with homobifunctional reagent dithiobis[succinimidyl propionate], which reacts amino group lysine residues. The positions in subunit that were involved cross-linkings determined by using cysteine-generated mutants constructed site-directed mutagenesis ATP4. Cross-linking experiments heterobifunctional p-azidophenacyl bromide, has a spacer arm 9 Å, performed mitochondria and crude Triton X-100...

The modifications induced by reactive oxygen species (ROS) on fluorescent proteins (FPs) may have important implications for live cell fluorescence imaging. Using quantitative gamma-radiolysis, we studied the ROS-induced biochemical and photophysical perturbations recombinant cyan protein (CFP). After oxidation OH radical, displays a modified RP-HPLC elution profile, while CFP undergoes pronounced decreases in intensity lifetime, without changes its excitation emission spectra. Meanwhile,...

Abstract Background In many eukaryotic cells, double-stranded RNA (dsRNA) triggers interference (RNAi), the specific degradation of homologous sequence. RNAi is now a major tool for reverse-genetics projects, including large-scale high-throughput screens. Recent reports have questioned specificity RNAi, raising problems in interpretation RNAi-based experiments. Results Using protozoan Trypanosoma brucei as model, we designed functional complementation assay to ascertain that phenotypic...

Abstract: A combination of posttranslational modifications contributes to the high heterogeneity brain tubulin in mammals. In this report, structures detyrosinated carboxy‐terminal peptides α‐tubulin from newborn and adult mouse were compared. The these was observed increase tubulin. major part increased is due excision Glu 450 , which makes nontyrosinatable (Δ‐2 tubulin). polyglutamyl side chain bi‐ triglutamylated analyzed work. polyglutamylation α‐tubulin, first glutamyl residue can only...

Abstract Summary: With the ever-increasing demand for biopolymer mass spectrometry, specialized software is needed to both predict and process spectrometric data. massXpert, we present a proteomics-oriented program mainly concerned with protein physico-chemistry protein/peptide spectra simulations. Availability: The massXpert free academic commercial use at http://frl.lptc.u-bordeaux.fr. Contact: frusconi@lptc.u-bordeaux.fr Supplementary information: http://frl.lptc.u-bordeaux.frsite...

DNA ends get exposed in cells upon either normal or dysfunctional cellular processes molecular events. Telomeres need to be protected by the shelterin complex avoid junctions occurring between chromosomes while failing topoisomerases clustered damage processing may produce double-strand breaks, thus requiring swift repair cell death. The rigorous study of great many proteins involved maintenance integrity is a challenging task because innumerous unspecific electrostatic and/or hydrophobic...

A rapid and efficient sample preparation method is described that allows analysis of biopolymer mixtures by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Very low amounts complex can be analyzed MALDI MS without any apparent loss material with a substantial gain in time combining chromatographic separation single operation. This micropurification based on both the formation submicroliter reversed-phase bed use matrix-containing eluent solutions. In this way,...

Nowadays, a variety of (bio-)polymers can be analyzed by mass spectrometry. The detailed interpretation the spectra requires huge number "hypothesis cycles", comprising following three actions 1) put forth structural hypothesis, 2) test it, 3) (in)validate it. This time-consuming and painstaking data scrutiny is alleviated using specialized software tools. However, all tools available to date are polymer chemistry-specific. imposes heavy overhead researchers who do spectrometry on...

Purification of specific DNA–protein complexes is a challenging task, as the involved interactions can be both electrostatic/H-bond and hydrophobic. The chromatographic stringency needed to obtain reasonable purifications uses salts detergents. However, these components elicit removal proteins unspecifically bound support itself, thus contaminating purification products. In this work, photocleavable linker connected target oligonucleotidic sequence beads so allow irradiation-based release...