Computational modeling and functional characterization of a GgChi: A class III chitinase from corms of Gladiolus grandiflorus

Authors

• Maria Rafiq, Bahauddin Zakariya University
• Ashiq Hussain, Technical University of Munich
• Kausar Hussain Shah, Bahauddin Zakariya University
• Qamar Saeed, Bahauddin Zakariya University
• Muhammad Umair Sial, Chinese Academy of Agricultural Sciences
• Zahid Ali, COMSATS University Islamabad
• Friedrich Buck, University Medical Centre Hamburg-Eppendorf
• Richard E. Goodman, University of Nebraska-LincolnFollow
• Binish Khaliq, Bahauddin Zakariya University
• Uzma Ishaq, The Women University
• Mirza Ahsen Baig, Bahauddin Zakariya University
• Aisha Munawar, University of Engineering and Technology
• Seema Mahmood, Bahauddin Zakariya University
• Ahmed Akrem, Bahauddin Zakariya UniversityFollow

Document Type

Article

Date of this Version

10-12-2018

Citation

Kaohsiung Journal of Medical Sciences (2018) 34, 673-683

Comments

2018, Kaohsiung Medical University. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract

The present study describes the predicted model and functional characterization of an endochitinase (30 kDa) from corms of Gladiolus grandiflorus. ESI-QTOF-MS generated peptide showed 96% sequence homology with family 18, Class III acidic endochitinase of Gladiolus gandavensis. Purified G. grandiflorus chitinase (GgChi) hydrolyzed 4-methylumbelliferyl b-DN, N0,N00-triacetylchitotriose substrate showing specific endochitinase activity. Since no structural details of GgChi were available in the Protein Data Bank (PDB), a homology model was predicted using the coordinate information of Crocus vernus chitinase (PDB ID: 3SIM). Ramachandran plot indicated 84.5% in most favored region, 14.8% in additional and 0.6% in generously allowed region while no residue in disallowed region. The predicted structure indicated a highly conserved (b/a)8 (TIM barrel) structure similar to the family 18, class III chitinases. The GgChi also showed sequence and structural homologies with other active chitinases. The GgChi (50 mg/disc) showed no antibacterial activity, but did provide mild growth inhibition of phytopathogenic fungus Fusarium oxysporum at a concentration of 500 mg/well Similarly, insect toxicity bioassays of GgChi (50 mg) against nymphs of Bemisia tabaci showed 14% reduction in adult emergence and 14% increase in mortality rate in comparison to control values. The GgChi (1.5 mg) protein showed significant reduction in a population of flour beetle (Tribolium castaneum) after 35 days, but lower reactivity against rice weevil (Sitophilus oryzae). The results of this study provide detai.led insight on functional characterization of a family 18 class III acidic plant endochitinase.