Biology subjects

Wattiez, R.

Publications and source records attributed to Wattiez, R..

8 recordsLinked to original sources

bioRxiv2026

Identification of a key residue in the cellular transcription factor BCL11b important for its global acetylation and its nuclear localization

AO_SCPLOWBSTRACTC_SCPLOWThe cellular transcription factor BCL11b (B-cell CLL/lymphoma 11b) interacts with numerous cellular and viral factors to modulate gene expression positively or negatively. Post-translational modifications of BCL11b, such as SUMOylation and phosphorylation, have been documented to switch its transcriptional activity from a repressor to an activator state. In the present study, we investigated the acetylation of BCL11b and we identified the histone acetyltransferase p300 as able to acetylate BCL11b. Subsequently, we observed that the mutation of the lysine K686 residue of BCL11b (BCL11b K686R) influenced its global acetylation. Furthermore, the BCL11b K686R mutation also modulated the transcriptional regulation of BCL11b, including its activity in regulating the p21 and IL-2 promoters. This effect on transcriptional regulation was due to the importance of the lysine K686 residue for BCL11b nuclear localization. Our results underscore the critical role of the lysine K686 residue in BCL11b for its interaction with p300 and its nuclear localization, suggesting a possible function of p300 in the nuclear transport of BCL11b. Collectively, our findings contribute to a better understanding of BCL11b-mediated gene expression and of the interactions of BCL11b with cellular partners.

molecular biology↗

bioRxiv2025

New Swiss-knife activities of GroEL/Hsp60 proteins

GroEL/Hsp60 chaperonins are key proteins that control cell metabolism, stress adaptation and survival. They usually form a tetradecameric structure that assists, coupled to ATP hydrolysis, 10% of all cellular protein folding. Using recombinant E. coli, human mitochondrial and M. tuberculosis chaperonins, we found that these proteins have thioesterase, esterase and even, for some of them, auto-acyltransferase activities. The smaller oligomers of Hsp60 and M. tuberculosis GroEL1 were more prone to use the long acyl carbon chain substrate palmitoyl-CoA compared to tetradecameric E. coli GroEL and Hsp60. Enzymatic competition and replacement of M. tuberculosis GroEL1 residues allow identifying Asp86 and Thr89 in the ATP-binding pocket and an additional Ser393 influencing the thioesterase activity. Additionally, M. tuberculosis GroEL1 might enhance palmitoylation of the PpsE protein, which plays a role in the phthiocerol dimycocerosate (PDIM) biosynthesis. This could explain at least partly the involvement of GroEL1 in PDIM biosynthesis and antibiotic resistance.

biochemistry↗

bioRxiv2025

Carotenoid-based immune response in sea cucumbers relies on newly identified coelomocytes -- the carotenocytes

Sea cucumbers (Holothuroidea, Echinodermata) are marine deuterostomes possessing a complex innate immune system composed of a wide diversity of immune cells--coelomocytes, making them compelling models for exploring the evolution of immunity. This study investigates the functional specialisation of coelomocytes within the two main echinoderm body fluids, namely the perivisceral fluid (PF) from the perivisceral cavity and the hydrovascular fluid (HF) from the hydrovascular-- ambulacral system. Given their specific distribution restricted to the HF, hemocyte-like cells (HELs) are particularly investigated. In echinoderms, hemocytes have been described as reddish cells containing haemoglobin and thus presenting a function in oxygen transport. Using an integrative approach combining cell morphological analyses, pigment profiling and multi-omics technologies, we demonstrate, in the sea cucumber Holothuria forskali, that HELs harbour exceptionally high concentrations of carotenoids, primarily canthaxanthin and astaxanthin--potent antioxidant molecules responsible for their pigmentation. Transcriptomics and proteomics analyses reveal that HELs express candidate genes involved in the carotenoid metabolism pathway as well as catalase, an antioxidant enzyme. Additionally, spectral flow cytometry assays reveal that HELs do not produce reactive oxygen species in contrast to most coelomocyte types, reinforcing the hypothesis of their antioxidant function. HELs also contribute to the formation of large red bodies (i.e., coelomocyte aggregates) and increase in concentration following lipopolysaccharide injections, indicating an active role in immune defence. Given these results, we hypothesise that these cells act after the culmination of the immune response, forming an antioxidant shell around the cellular aggregates to mitigate oxidative stress from reactive oxygen species (ROS) produced within the aggregate while encapsulating pathogens, thus protecting the host tissues. The discovery of carotenoid-carrying coelomocytes constitutes the first report of pigmented coelomocytes in sea cucumbers (except respiratory pigments), challenging the long-standing assumption that these cells contain haemoglobin. Therefore, we propose renaming hemocytes into carotenocytes, at least in this species. However, we think that this newly described coelomocyte type has been wrongly identified as haemoglobin-containing cells in many previous studies and could be present in many other holothuroid species. Our findings thus establish a new paradigm in the study of coelomocytes in echinoderms as well as the function of the hydrovascular system, unique to this phylum.

evolutionary biology↗

bioRxiv2024

Abundance, diversity and evolution of tyrosinase enzymes involved in the adhesive systems of mussels and tubeworms

The blue mussel (Mytilus edulis) and the honeycomb tubeworm (Sabellaria alveolata) have evolved similar adhesive systems to cope with the hydrodynamic conditions of the intertidal environment where they live. Both organisms can establish a permanent adhesion through the secretion of adhesive proteins rich in DOPA (3,4-dihydroxyphenylalanine), a post-translationally modified amino acid playing essential roles in interfacial adhesion and bulk cohesion. DOPA is produced by the hydroxylation of tyrosine residues by tyrosinase enzymes, which can also in some cases oxidise it further into dopaquinone Compared to the detailed knowledge available on mussel and tubeworm adhesive proteins, little information exists about the tyrosinases involved in their adhesive systems. By combining different molecular analyses, a catalogue of tyrosinase candidates potentially involved in the adhesive systems of M. edulis and S. alveolata was identified. Some of these candidates were shown to be expressed in the adhesive glands by in situ hybridization, with a high gland-specificity in mussels but not in tubeworms. The diversity of tyrosinases highlighted in the two species suggests the coexistence of different functions (monophenol monooxygenase or catechol oxidase activity) or different substrate specificities. However, the exact role of the different enzymes needs to be further investigated. Phylogenetic analyses support the hypothesis of independent expansions and parallel evolution of tyrosinases involved in adhesive protein maturation in both lineages, supporting the convergent evolution of their DOPA-based adhesion.

evolutionary biology↗

bioRxiv2022

The ribosome inhibitor chloramphenicol induces motility deficits in human spermatozoa: a proteomic approach identifies potentially involved proteins

Mature spermatozoa are almost completely devoid of cytoplasm; as such it has long been believed that they do not contain ribosomes and are therefore not capable of synthesising proteins. However, since the 1950s, various studies have shown translational activity within spermatozoa, particularly during their in vitro capacitation. Most of them demonstrated that mitochondrial (and not cytoplasmic) ribosomes would be involved in the translation of mitochondrial and nuclear-encoded cytoplasmic mRNAs. However, some evidence suggests that cytoplasmic ribosomes could also be active. Here, we investigate the presence and activity of the two types of ribosomes in mature human spermatozoa. By targeting ribosomal RNAs and proteins, we show that both types of ribosomes are localized in the midpiece as well as in the neck and the base of the head of the spermatozoa. We assessed the impact of cycloheximide (CHX) and chloramphenicol (CP), inhibitors of cytoplasmic and mitochondrial ribosomes, respectively, on different sperm parameters. Neither CHX, nor CP impacted sperm vitality, mitochondrial activity (measured through the ATP content), or capacitation (measured through the content in phosphotyrosines). However, increasing CP concentrations induced a decrease in total and progressive motilities as well as on some kinematic parameters while no effect was observed with CHX. A quantitative proteomic analysis was performed by mass spectrometry in SWATH mode to compare the proteomes of spermatozoa capacitated in the absence or presence of the two ribosome inhibitors. Among the [~] 700 proteins identified in the different tested conditions, 3, 3 and 25 proteins presented a modified abundance in the presence of 1 and 2 mg/ml of CHX, and 1 mg/ml of CP, respectively. The observed abundance variations of some CP-down regulated proteins were validated using Multiple-Reaction Monitoring (MRM). Taken together, our results show that the sperm motility deficits induced in the presence of CP could be linked to the observed decrease of the abundance of several proteins, at least FUNDC2 and QRICH2.

cell biology↗

bioRxiv2020

Unraveling Oxidative Stress Resistance: Molecular Properties Govern Proteome Vulnerability

AbstractOxidative stress alters cell viability, from microorganism irradiation sensitivity to human aging and neurodegeneration. Deleterious effects of protein carbonylation by reactive oxygen species (ROS) make understanding molecular properties determining ROS-susceptibility essential. The radiation-resistant bacterium Deinococcus radiodurans accumulates less carbonylation than sensitive organisms, making it a key model for deciphering properties governing oxidative stress resistance. We integrated shotgun redox proteomics, structural systems biology, and machine learning to resolve properties determining protein damage by {gamma}-irradiation in Escherichia coli and D. radiodurans at multiple scales. Local accessibility, charge, and lysine enrichment accurately predict ROS-susceptibility. Lysine, methionine, and cysteine usage also contribute to ROS-resistance of the D. radiodurans proteome. Our model predicts proteome maintenance machinery and proteins protecting against ROS are more resistant in D. radiodurans. Our findings substantiate that protein-intrinsic protection impacts oxidative stress resistance, identifying causal molecular properties. One Sentence SummaryProteins differ in intrinsic susceptibility to oxidation, a mode of evolutionary adaptation for stress tolerance in bacteria.

systems biology↗

bioRxiv2019

Deciphering the functioning of microbial communities: shedding light on the critical steps in metaproteomics

Unraveling the complex structure and functioning of microbial communities is essential to accurately predict the impact of perturbations and/or environmental changes. From all molecular tools available today to resolve the dynamics of microbial communities, metaproteomics stands out, allowing the establishment of phenotype-genotype linkages. Despite its rapid development, this technology has faced many technical challenges that still hamper its potential power. How to maximize the number of protein identification, improve quality of protein annotation and provide reliable ecological interpretation, are questions of immediate urgency. In our study, we used a robust metaproteomic workflow combining two protein fractionation approaches (gel-based versus gel-free) and four protein search databases derived from the same metagenome to analyze the same seawater sample. The resulting eight metaproteomes provided different outcomes in terms of (i) total protein numbers, (ii) taxonomic structures, and (iii) protein functions. The characterization and/or representativeness of numerous proteins from ecologically relevant taxa such as Pelagibacterales, Rhodobacterales and Synechococcales, as well as crucial environmental processes, such as nutrient uptake, nitrogen assimilation, light harvesting and oxidative stress response were found to be particularly affected by the methodology. Our results provide clear evidences that the use of different protein search databases significantly alters the biological conclusions in both gel-free and gel-based approaches. Our findings emphasize the importance of diversifying the experimental workflow for a comprehensive metaproteomic study.

microbiology↗

bioRxiv2018

Thioredoxins induce oocyte maturation in holothuroids (Echinodermata)

Chromatographic fractions of a rough extract of echinoid spawn (REES) has been demonstrated to efficiently induce oocyte maturation in aspidochirote holothuroids. The method is so efficient that it is now used in holothuriculture to get fertilised eggs even outside the reproductive period of the aquacultured species. We here isolate and identify from echinoid spawns the molecule responsible for the induction of the oocyte maturation in the Mediterranean holothuroid Holothuria tubulosa and the Indo-Pacific Holothuria scabra. The use of proteinase K and dialysing membranes indicates that the active molecule is a protein with a molecular weight superior to 12,000 kDa. The active molecule has been isolated on G-100 Sephadex chromatography column. Active chromatographic fractions include seven proteins identified with nanoLC-MS/MS technique. One of them, identify as a thioredoxin-2 and to which the name Trx-REES has been given, leads up to levels of maturation similar to those obtained with the REES and with a commercial thioredoxin extracted from Escherichia coli. Occurrence of thioredoxin in REES was confirmed by immunoblot analysis, and the maturation-inducing properties of thioredoxin were positively checked in using anti-thioredoxin antibodies. A peptide of 6 AAs corresponding to the active site of Trx-REES, composed of WCNPCK, was synthesised and its efficiency in holothuroid oocyte maturation tested. At some concentrations, the peptide was 1.2 times more active than the REES.

zoology↗