title: An unconventional antimicrobial protein histone from freshwater prawn Macrobrachium rosenbergii: analysis of immune properties.
abstract: In this study, we have reported the first histone characterized at molecular level from freshwater prawn Macrobrachium rosenbergii (MrHis). A full length cDNA of MrHis (751 base pairs) was identified from an established M. rosenbergii cDNA library using GS-FLX technique. It encodes 137 amino acid residues with a calculated molecular mass of 15 kDa and an isoelectric point of 10.5. MrHis peptide contains a histone H2A signature between 21 and 27 amino acids. Homologous analysis showed that MrHis had a significant sequence identity (99%) with other known histone H2A groups especially from Penaeus monodon. Phylogenetic analysis of MrHis showed a strong relationship with other amino acid sequences from histone H2A arthropod groups. Further phylogenetic analysis showed that the MrHis belongs to histone H2A superfamily and H2A1A sub-family. Secondary structure of MrHis showed that the protein contains 50.36% α-helical region and 49.64% coils. The 3D model of MrHis was predicted by I-Tasser program and the model was evaluated for quality analysis including C-score analysis, Ramachandran plot analysis and RMSD analysis. The surface view analysis of MrHis showed the active domain at the N terminal. The antimicrobial property of MrHis protein was confirmed by the helical structure and the total hydrophobic surface along with its net charge. The MFE of the predicted RNA structure of MrHis is -128.62 kcal/mol, shows its mRNA stability. Schiffer-Edmundson helical wheel analysis of the N-terminal of MrHis showed a perfect amphipathic nature of the peptide. Significantly (P < 0.05) highest gene expression was noticed in the hemocyte and is induced with viral (WSBV and MrNV) and bacteria (A eromonas hydrophila and Vibrio harveyi) infections. The coding sequence of recombinant MrHis protein was expressed in a pMAL vector and purified to study the antimicrobial properties. The recombinant product showed antimicrobial activity against both Gram negative and Gram positive bacteria. In this study, the recombinant MrHis protein displayed antimicrobial activity in its entirety. Hence, it is possible to suggest that the activity may be due to the direct defense role of histone or its N-terminal antimicrobial property. However, this remains to be verified by detailed investigations.
authors.affiliation: Division of Fisheries Biotechnology & Molecular Biology, Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, Chennai 603 203, Tamil Nadu, India. Electronic address: jesuaraj@hotmail.com.
authors.forename: Jesu
authors.initials: J
authors.lastname: Arockiaraj
authors.forename: Annie J
authors.initials: AJ
authors.lastname: Gnanam
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Kumaresan
authors.forename: Rajesh
authors.initials: R
authors.lastname: Palanisamy
authors.forename: Prasanth
authors.initials: P
authors.lastname: Bhatt
authors.forename: Muthukumaresan Kuppusamy
authors.initials: MK
authors.lastname: Thirumalai
authors.forename: Arpita
authors.initials: A
authors.lastname: Roy
authors.forename: Mukesh
authors.initials: M
authors.lastname: Pasupuleti
authors.forename: Marimuthu
authors.initials: M
authors.lastname: Kasi
mesh_terms: D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D006434:Hemocytes / Q000276:immunology / Q000378:metabolism; D006657:Histones / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D013294:Lactococcus lactis / Q000276:immunology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D033541:Palaemonidae / Q000235:genetics* / Q000276:immunology; D010802:Phylogeny; D011487:Protein Conformation; D020871:RNA Stability / Q000235:genetics; D011994:Recombinant Proteins / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA / Q000662:veterinary; D017385:Sequence Homology; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D006657:Histones; D011994:Recombinant Proteins
keywords: Antimicrobial activity; Bioinformatics; Gene expression; Histone; Prawn