Sylvain Cottaz

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BACKGROUND Myrosinase is the enzyme responsible for the hydrolysis of a variety of plant anionic 1-thio-beta-D-glucosides called glucosinolates. Myrosinase and glucosinolates, which are stored in different tissues of the plant, are mixed during mastication generating toxic by-products that are believed to play a role in the plant defence system. Whilst(More)
Most land plants live symbiotically with arbuscular mycorrhizal fungi. Establishment of this symbiosis requires signals produced by both partners: strigolactones in root exudates stimulate pre-symbiotic growth of the fungus, which releases lipochito-oligosaccharides (Myc-LCOs) that prepare the plant for symbiosis. Here, we have investigated the events(More)
Myrosinase, an S-glycosidase, hydrolyzes plant anionic 1-thio-beta-d-glucosides (glucosinolates) considered part of the plant defense system. Although O-glycosidases are ubiquitous, myrosinase is the only known S-glycosidase. Its active site is very similar to that of retaining O-glycosidases, but one of the catalytic residues in O-glycosidases, a(More)
Plant XETs [XG (xyloglucan) endotransglycosylases] catalyse the transglycosylation from a XG donor to a XG or low-molecular-mass XG fragment as the acceptor, and are thought to be important enzymes in the formation and remodelling of the cellulose-XG three-dimensional network in the primary plant cell wall. Current methods to assay XET activity use the XG(More)
The thermoacidophilic archaeon Sulfolobus solfataricus P2 encodes three hypothetic endo-beta-glucanases, SSO1354, SSO1949 and SSO2534. We cloned and expressed the gene sso1949 encoding the 334 amino acids containing protein SSO1949, which can be classified as a member of glycoside hydrolase family 12. The purified recombinant enzyme hydrolyses(More)
Establishment of arbuscular mycorrhizal interactions involves plant recognition of diffusible signals from the fungus, including lipochitooligosaccharides (LCOs) and chitooligosaccharides (COs). Nitrogen-fixing rhizobial bacteria that associate with leguminous plants also signal to their hosts via LCOs, the so-called Nod factors. Here, we have assessed the(More)
Chitinbiose was produced at more than 4 g L-1 by a high cell density culture of an Escherichia coli strain that co-expressed the rhizobial chitinoligosaccharide synthase gene nodC and a truncated form of the chitinase gene chiA which has been designed to be functionally produced in the E. coli cytoplasm. Chitinpentaose, which has previously been shown to be(More)
Surface plasmon resonance (SPR) has been used to assay the roles of amino acid residues in the substrate binding cleft of Trichoderma harzianum chitinase Chit42, which belongs to the glycoside hydrolase family 18 (GH-18). Nine different Chit42 variants having amino acid mutations along the binding site cleft at subsites -4 to +2 were created and(More)
Root hairs are involved in water and nutrient uptake, and thereby in plant autotrophy. In legumes, they also play a crucial role in establishment of rhizobial symbiosis. To obtain a holistic view of Medicago truncatula genes expressed in root hairs and of their regulation during the first hours of the engagement in rhizobial symbiotic interaction, a high(More)
The binding to glucoamylase 1 from Aspergillus niger (GA1) of a series of four synthetic heterobidentate ligands of acarbose and beta-cyclodextrin (beta-CD) linked together has been studied by isothermal titration calorimetry. GA1 consists of a catalytic and a starch-binding domain (SBD) connected by a heavily O-glycosylated linker region. Acarbose is a(More)