A partial cDNA sequence from Anacardium occidentale CCP 76 was obtained, encoding a GH19 chitinase (AoChi) belonging to class VI. AoChi exhibits distinct structural features in relation to previously characterized plant GH19 chitinases from classes I, II, IV and VII. For example, a conserved Glu residue at the catalytic center of typical GH19 chitinases, which acts as the proton donor during catalysis, is replaced by a Lys residue in AoChi. To verify if AoChi is a genuine chitinase or is a chitinase-like protein that has lost its ability to degrade chitin and inhibit the growth of fungal pathogens, the recombinant protein was expressed in Pichia pastoris, purified and biochemically characterized. Purified AoChi (45 kDa apparent molecular mass) was able to degrade colloidal chitin, with optimum activity at pH 6.0 and at temperatures from 30 °C to 50 °C. AoChi activity was completely lost when the protein was heated at 70 °C for 1 h or incubated at pH values of 2.0 or 10.0. Several cation ions (Al, Cd, Ca, Pb, Cu, Fe, Mn, Rb, Zn and Hg), chelating (EDTA) and reducing agents (DTT, β-mercaptoethanol) and the denaturant SDS, drastically reduced AoChi enzymatic activity. AoChi chitinase activity fitted the classical Michaelis-Menten kinetics, although turnover number and catalytic efficiency were much lower in comparison to typical GH19 plant chitinases. Moreover, AoChi inhibited in vitro the mycelial growth of Lasiodiplodia theobromae, causing several alterations in hyphae morphology. Molecular docking of a chito-oligosaccharide in the substrate-binding cleft of AoChi revealed that the Lys residue (theoretical pK = 6.01) that replaces the catalytic Glu could act as the proton donor during catalysis.
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http://dx.doi.org/10.1016/j.phytochem.2020.112527 | DOI Listing |
Rheumatology (Oxford)
July 2024
Department of Otolaryngology-Head and Neck Surgery, Sapporo Medical University School of Medical, Sapporo, Japan.
Objective: To identify genes that could provide clues leading to the discovery of drugs to treat IgG4-related disease (IgG4-RD).
Methods: Submandibular gland tissue bulk RNAseq analysis of 45 cases with a definite diagnosis of IgG4-RD was integrated with Visium spatial transcriptome analysis of 2 cases to identify pathogenic genes expressed in tertiary lymphoid tissues.
Results: Bulk RNAseq and pathway analyses showed upregulation of cell cycle and T cell-related signals in IgG4-RD.
Mod Rheumatol Case Rep
July 2024
Department of Rheumatology and Allergy, IMSUT Hospital, Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
Glucocorticoids (GC) are the standard of care for the induction and maintenance of remission in immunoglobulin G4 (IgG4)-related diseases. However, IgG4-related diseases often relapse with GC dose reduction, not only making GC dose reduction difficult but also necessitating GC dose escalation in many cases. Therefore, other immunosuppressive drugs are required to maintain remission.
View Article and Find Full Text PDFEnviron Health Prev Med
April 2024
Osaka Regional Center for Japan Environment and Children's Study (JECS), Osaka University.
Background: Few prospective cohort studies have examined the association between maternal diabetes, including pre-pregnancy and gestational diabetes, and the risk of congenital heart disease (CHD) in Asian offspring.
Methods: We examined the association between maternal diabetes and offspring CHD among 97,094 mother-singleton infant pairs in the Japan Environment and Children's Study (JECS) between January 2011 and March 2014. Odds ratios (OR) and 95% confidence intervals (CI) of offspring CHD based on maternal diabetes (pre-pregnancy diabetes and gestational diabetes) were estimated using logistic regression after adjusting for maternal age at delivery, pre-pregnancy body mass index (BMI), maternal smoking habits, alcohol consumption, annual household income, and maternal education.
Environ Health Prev Med
March 2024
Osaka Regional Center for Japan Environment and Children's Study (JECS), Osaka University.
JAMA Netw Open
January 2024
Institute for Global Health Policy Research, Bureau of International Health Cooperation, National Center for Global Health and Medicine, Tokyo, Japan.
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