Functional Characterization ofCsBGlu12, a β-Glucosidase fromCrocus sativus, Provides Insights into Its Role in Abiotic Stress through Accumulation of Antioxidant Flavonols.
Glycosylation and deglycosylation are impressive mechanisms that allow plants to regulate the biological activity of an array of secondary metabolites. Although glycosylation improves solubility and renders the metabolites suitable for transport and sequestration, deglycosylation activates them to carry out biological functions. Herein, we report the functional characterization ofCsBGlu12, a β-glucosidase fromCrocus sativus. CsBGlu12 has a characteristic glucoside hydrolase 1 family (α/β)8triose-phosphate isomerase (TIM) barrel structure with a highly conserved active site.In vitroenzyme activity revealed thatCsBGlu12 catalyzes the hydrolysis of flavonol β-glucosides and cello-oligosaccharides. Site-directed mutagenesis of any of the two conserved catalytic glutamic acid residues (Glu200and Glu414) of the active site completely abolishes the β-glucosidase activity. Transcript analysis revealed thatCsbglu12is highly induced in response to UV-B, dehydration, NaCl, methyl jasmonate, and abscisic acid treatments indicating its possible role in plant stress response. Transient overexpression ofCsBGlu12 leads to the accumulation of antioxidant flavonols inNicotiana benthamianaand confers tolerance to abiotic stresses. Antioxidant assays indicated that accumulation of flavonols alleviated the accretion of reactive oxygen species during abiotic stress conditions. β-Glucosidases are known to play a role in abiotic stresses, particularly dehydration through abscisic acid; however, their role through accumulation of reactive oxygen species (ROS) scavenging flavonols has not been established. Furthermore, only one β-glucosidase 12 homolog has been characterized so far. Therefore, this work presents an important report on characterization ofCsBGlu12 and its role in abiotic stress through ROS scavenging.
From the Plant Biotechnology Division, Council of Scientific and Industrial Research-Indian Institute of Integrative Medicine, Sanat Nagar, Srinagar, Jammu and Kashmir 190005 and.|the Academy of Scientific and Innovative Research and.
Shoib Ahmad
SA
Baba
Medicinal Chemistry Division, Council of Scientific and Industrial Research-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi-180001, India.
Ram A
RA
Vishwakarma
From the Plant Biotechnology Division, Council of Scientific and Industrial Research-Indian Institute of Integrative Medicine, Sanat Nagar, Srinagar, Jammu and Kashmir 190005 and nashraf@iiim.ac.in.|the Academy of Scientific and Innovative Research and.
Nasheeman
N
Ashraf
D000595:Amino Acid Sequence; D000975:Antioxidants / Q000378:metabolism; D027622:Crocus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D018360:Crystallography, X-Ray; D044948:Flavonols / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008958:Models, Molecular; D010802:Phylogeny; D011487:Protein Conformation; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013312:Stress, Physiological; D001617:beta-Glucosidase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
D000975:Antioxidants; D044948:Flavonols; D017382:Reactive Oxygen Species; D001617:beta-Glucosidase
enzyme kinetics; flavonoid; plant; reactive oxygen species (ROS); stress