Please cite this article in press as: G. Ravichandran, et al., Int. J. Biol. Macromol. (2017), http://dx.doi.org/10.1016/j.ijbiomac.2017.08.098 ARTICLE IN PRESS G Model BIOMAC-8090; No. of Pages 9 International Journal of Biological Macromolecules xxx (2017) xxx–xxx Contents lists available at ScienceDirect International Journal of Biological Macromolecules j ourna l h o mepa ge: www.elsevier.com/locate/ijbiomac Bactericidal and fungistatic activity of peptide derived from GH18 domain of prawn chitinase 3 and its immunological functions during biological stress Gayathri Ravichandran a,b , Venkatesh Kumaresan a , Arun Mahesh c , Arunkumar Dhayalan c , Aziz Arshad d , Mariadhas Valan Arasu e , Naif Abdullah Al-Dhabi e , Mukesh Pasupuleti f , Jesu Arockiaraj a,∗ a Division of Fisheries Biotechnology & Molecular Biology, Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur 603 203, Chennai, Tamil Nadu, India b SRM Research Institute, SRM University, Kattankulathur 603 203, Chennai, Tamil Nadu, India c Department of Biotechnology, Pondicherry University, Puducherry 605 014, India d Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia e Addiriyah Research Chair for Environmental Studies, Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia f Lab PCN 206, Microbiology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, Uttar Pradesh, India a r t i c l e i n f o Article history: Received 1 July 2017 Received in revised form 16 August 2017 Accepted 16 August 2017 Available online xxx Keywords: Chitinase GH18 Peptide Bactericidal Fungistatic a b s t r a c t Chitinases play a vital role during the pathogenic invasion and immunosuppression in various organisms including invertebrates and vertebrates. In this study, we have investigated the participation of MrChit- 3 (Macrobrachium rosenbergii Chitinase-3) during host-pathogenic interaction in freshwater prawn, M. rosenbergii. Quantitative real-time PCR analysis showed that the expression of MrChit-3 was up-regulated during bacterial, viral and laminarin challenge. Moreover, to understand the antimicrobial role of the GH18 domain, a putative membrane-targeting antimicrobial peptide (MrVG) was identified from the GH18 domain region of the protein and it was chemically synthesized. Physico-chemical features of the GH18 derived antimicrobial peptide (AMP) was assessed by various in silico tools and the antimicrobial property of the peptide was confirmed from in vitro studies. The membrane targeting mechanism of the peptide was determined by flow cytometry (FACS) and scanning electron microscope (SEM) analysis. Interestingly, the peptide was able to inhibit the growth of a chitinolytic fungal pathogen, Aspergillus niger, which was isolated from the shells of M. rosenbergii. The toxicity studies such as hemolysis activity on human blood erythrocytes and cell viability assay with primary kidney cells, HEK293 of MrVG revealed that the peptide was not involved in inducing any toxicity. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Among the cascade of immune mechanisms, the production of chitinases is one of the fundamental immunogenic responses in diverse organisms during the invasion of pathogens and in stress conditions. Chitinases function as a hydrolytic enzyme, which cleaves the glycosidic linkage of the polymer chitin. Chitin is an important constituent of the fungal cell wall and functions as a structural element in crustaceans and arthropods [1]. Previous investigations proved that chitinases are a potential component ∗ Corresponding author. E-mail address: jesuaraj@hotmail.com (J. Arockiaraj). in experimental antifungal therapy. As a major immune response in the interaction between host and pathogens (fungi, insects and some bacteria), chitinases are produced to directly fight against them by attacking the chitin of the exoskeleton [2]. Similarly, the mammalian chitinases have been detected during disease condi- tions and are used as potential biomarkers in the diseases such as Gaucher disease, malaria, liver fibrosis, inflammatory bowel dis- ease and atherosclerosis [3]. Recent studies also supported that a significant increase in expression of chitinases detected in asthma and allergic conditions [4]. Chitinases are categorized into two major families GH18 and GH19, based on the glycoside hydrolase (GH) domains. The two members are highly variant from each other which are found not to have any sequence similarity and it exhibited varied protein struc- http://dx.doi.org/10.1016/j.ijbiomac.2017.08.098 0141-8130/© 2017 Elsevier B.V. All rights reserved.