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International audience; The chloroplast protein CP12, which is widespread in photosynthetic organisms, belongs to the intrinsically disordered proteins family. This small protein (80 amino acid residues long) presents a bias in its composition; it is enriched in charged amino acids, has a small number of hydrophobic residues, and has a high proportion of disorder-promoting residues. More precisely, CP12 is a conditionally disordered proteins (CDP) dependent upon the redox state of its four cysteine residues. During the day, reducing conditions prevail in the chloroplast, and CP12 is fully disordered. Under oxidizing conditions (night), its cysteine residues form two disulfide bridges that confer some stability to some structural elements. Like many CDPs, CP12 plays key roles, and its redox-dependent conditional disorder is important for the main function of CP12: the dark/light regulation of the Calvin-Benson-Bassham (CBB) cycle responsible for CO2 assimilation. Oxidized CP12 binds to glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase and thereby inhibits their activity. However, recent studies reveal that CP12 may have other functions beyond the CBB cycle regulation. In this review, we report the discovery of this protein, its features as a disordered protein, and the many functions this small protein can have.

International audience; The chloroplast protein CP12 is involved in the dark/light regulation of the Calvin–Benson–Bassham cycle, in particular, in the dark inhibition of two enzymes: glyceraldehyde−3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK), but other functions related to stress have been proposed. We knocked out the unique CP12 gene to prevent its expression in Chlamydomonas reinhardtii (ΔCP12). The growth rates of both wild-type and ΔCP12 cells were nearly identical, as was the GAPDH protein abundance and activity in both cell lines. On the contrary, the abundance of PRK and its specific activity were significantly reduced in ΔCP12, as revealed by relative quantitative proteomics. Isolated PRK lost irreversibly its activity over-time in vitro, which was prevented in the presence of recombinant CP12 in a redox-independent manner. We have identified amino acid residues in the CP12 protein that are required for this new function preserving PRK activity. Numerous proteins involved in redox homeostasis and stress responses were more abundant and the expressions of various metabolic pathways were also increased or decreased in the absence of CP12. These results highlight CP12 as a moonlighting protein with additional functions beyond its well-known regulatory role in carbon metabolism.

International audience; Deep eutectic solvents as extraction media for polar bioactives from wheat bran. 12 SLACA Symposium Latin American of Food Science

Ensuring adequate growth of preterm newborns remains a challenge. When breastfeeding is not possible, pasteurized human milk (PHM) from milk banks is preferentially administered to hospitalized newborns. Holder pasteurization (62.5°; 30 min) is applied for sanitary reasons but may reduce fat absorption through the inactivation of milk endogenous lipases. It has been suggested that homogenization of Holder-pasteurized human milk (PHM) could improve fat absorption and weight gain. The objective of the present work was to determine the impact of pasteurization and homogenization on gastric digestion in preterm infants. In a randomized controlled trial (NCT02112331), hospitalized tube-fed preterm infants were their own control to compare the gastric digestion of either i) raw (RHM) and pasteurized human milk (PHM), or ii) pasteurized (PHM) and homogenized PHM (PHHM). Over a six-day sequence, gastric aspirates were collected twice a day, before and 35, 60 or 90 min after the start of milk ingestion. The impact of homogenization on PHM digestive kinetics, lipolytic activity and disintegration was monitored. Pasteurization and homogenization affected milk initial structure, with the formation of protein aggregates at the interface of the milk fat globules in PHM and a six-fold increase of the specific surface (P

Human milk is the ideal food for infant nutrition. Understanding the digestive behavior of this natural complex colloidal emulsion is essential for neonatal nutrition and a key step in developing infant formulas with optimized health benefits. However, ethical reasons limit in vivo trials. Thus, it is important to develop relevant in vitro models. In this aim, a dynamic in vitro digestion system (DIDGI®) was applied to human milks or infant formula. The dynamic digester parameters were based on an exhaustive literature review to mimic closely the digestion of newborns. Raw or pasteurized pooled human milks (HM) or a liquid infant formula (IF) were digested in triplicate. In parallel, in vivo study was conducted on preterm newborns at Rennes Hospital (NCT02112331) to validate gastric in vitro data. Lipolysis, liberated fatty acids and the structural changes of the matrices were evaluated along digestion. HMs differed from IF in terms of chemical composition (specifically regiodistribution), prehydrolysis state and emulsion structure. These initial differences impacted lipolysis kinetics and deconstruction. In comparison, the pasteurization of HM only impacted emulsion disintegration, protein aggregation and the persistence of native fat globules. Our model will be useful to the scientist community and food manufacturers who focus on neonatal digestion and infant formulas optimization.

International audience; Background Few studies have tested the small intestine microbiota in humans, where most nutrient digestion and absorption occur. Here, our objective was to examine the duodenal microbiota between obese and normal volunteers using metagenomic techniques. Methodology/Principal Findings We tested duodenal samples from five obese and five normal volunteers using 16S rDNA V6 pyrosequencing and Illumina MiSeq deep sequencing. The predominant phyla of the duodenal microbiota were Firmicutes and Actinobacteria, whereas Bacteroidetes were absent. Obese individuals had a significant increase in anaerobic genera (p < 0.001) and a higher abundance of genes encoding Acyl-CoA dehydrogenase (p = 0.0018) compared to the control group. Obese individuals also had a reduced abundance of genes encoding sucrose phosphorylase (p = 0.015) and 1,4-alpha-glucan branching enzyme (p = 0.05). Normal weight people had significantly increased FabK (p = 0.027), and the glycerophospholipid metabolism pathway revealed the presence of phospholipase A1 only in the control group (p = 0.05). Conclusions/Significance The duodenal microbiota of obese individuals exhibit alterations in the fatty acid and sucrose breakdown pathways, probably induced by diet imbalance.

International audience; BACKGROUND: Some Lactobacillus species are associated with obesity and weight gain while others are associated with weight loss. Lactobacillus spp. and bifidobacteria represent a major bacterial population of the small intestine where lipids and simple carbohydrates are absorbed, particularly in the duodenum and jejunum. The objective of this study was to identify Lactobacillus spp. proteins involved in carbohydrate and lipid metabolism associated with weight modifications. METHODS: We examined a total of 13 complete genomes belonging to seven different Lactobacillus spp. previously associated with weight gain or weight protection. We combined the data obtained from the Rapid Annotation using Subsystem Technology, Batch CD-Search and Gene Ontology to classify gene function in each genome. RESULTS: We observed major differences between the two groups of genomes. Weight gain-associated Lactobacillus spp. appear to lack enzymes involved in the catabolism of fructose, defense against oxidative stress and the synthesis of dextrin, L-rhamnose and acetate. Weight protection-associated Lactobacillus spp. encoded a significant gene amount of glucose permease. Regarding lipid metabolism, thiolases were only encoded in the genome of weight gain-associated Lactobacillus spp. In addition, we identified 18 different types of bacteriocins in the studied genomes, and weight gain-associated Lactobacillus spp. encoded more bacteriocins than weight protection-associated Lactobacillus spp. CONCLUSIONS: The results of this study revealed that weight protection-associated Lactobacillus spp. have developed defense mechanisms for enhanced glycolysis and defense against oxidative stress. Weight gain-associated Lactobacillus spp. possess a limited ability to breakdown fructose or glucose and might reduce ileal brake effects.

IATE : Axe 4 Biotechnologie microbienne et enzymatique des lipides et des agropolymères; International audience; Latex from Caricaceae has been known since 1925 to contain strong lipase activity. However, attempts to purify and identify the enzyme were not successful, mainly because of the lack of solubility of the enzyme. Here, we describe the characterization of lipase activity of the latex of Vasconcellea heilbornii and the identification of a putative homologous lipase from Carica papaya. Triacylglycerol lipase activity was enriched 74-fold from crude latex of Vasconcellea heilbornii to a specific activity (SA) of 57 lmolÆmin)1Æmg)1 on long-chain triacylglycerol (olive oil). The extract was also active on trioctanoin (SA = 655 lmolÆmin)1Æmg)1), tributyrin (SA = 1107 lmolÆmin)1Æmg)1) and phosphatidylcholine (SA = 923 lmolÆmin)1Æmg)1). The optimum pH ranged from 8.0 to 9.0. The protein content of the insoluble fraction of latex was analyzed by electrophoresis followed by mass spectrometry, and 28 different proteins were identified. The protein fraction was incubated with the lipase inhibitor [14C]tetrahydrolipstatin, and a 45 kDa protein radiolabeled by the inhibitor was identified as being a putative lipase. A C. papaya cDNA encoding a 55 kDa protein was further cloned, and its deduced sequence had 83.7% similarity with peptides from the 45 kDa protein, with a coverage of 25.6%. The protein encoded by this cDNA had 35% sequence identity and 51% similarity to castor bean acid lipase, suggesting that it is the lipase responsible for the important lipolytic activities detected in papaya latex.