title: Molecular cloning and functional characterization of a novel i-type lysozyme in the freshwater mussel Cristaria plicata.
abstract: The freshwater bivalve Cristaria plicata, which is widely distributed in Eastern Asia, is a key species in the pearl culture industry. In this study, a novel invertebrate-type lysozyme, designated as CpLYZ2, was cloned from hemocytes of C. plicata. This lysozyme shares high sequence identity and is homologous to a previously identified lysozyme CpLYZ1 isolated from C. plicata and with HcLyso3 isolated from Hyriopsis cumingii. The full-length cDNA of CpLYZ2 is 913 bp long, which includes an open reading frame (ORF) of 486 bp, a 3' untranslated region (UTR) of 389 bp and a 5' UTR of 38 bp. The ORF encodes a putative polypeptide of 161 amino acids with a predicted molecular mass of 18.2 kDa and a theoretical isoelectric point of 6.56. CpLYZ2 mRNA transcripts can be detected in hemocytes, hepatopancreas, muscle, gills and mantle tissues, the greatest expression being observed in the gills. CpLYZ2 expression in hemocytes, hepatopancreas and gills increased significantly after the mussel was challenged with Aeromonas hydrophila. Furthermore, the optimal pH and temperature for enzyme activity of the recombinant CpLYZ2 were 5.5 and 50°C, respectively. The recombinant lysozyme protein exhibited bacteriolytic activity against Escherichia coli, A. hydrophila, Staphylococcus aureus, Bacillus subtilis, Streptococcus sp. and Staphylococcus epidermidis. The findings of this study help to elucidate immune responses in molluscs and will thus expedite disease management of these key freshwater species, in turn boosting pearl culture in eastern Asia.
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Dai
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Dan
authors.initials: D
authors.lastname: Wu
authors.affiliation: College of Jiangxi Biotech Vocational, Nanchang 330200, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Chungen
authors.initials: C
authors.lastname: Wen
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Yanhai
authors.initials: Y
authors.lastname: Xie
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Baoqing
authors.initials: B
authors.lastname: Hu
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Jian
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Mingyu
authors.initials: M
authors.lastname: Zeng
authors.affiliation: School of Life Sciences, Nanchang University, Nanchang 330031.
authors.forename: Zhiying
authors.initials: Z
authors.lastname: Tao
mesh_terms: D016980:Aeromonas hydrophila; D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005618:Fresh Water; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D016366:Open Reading Frames; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D016415:Sequence Alignment; D017421:Sequence Analysis; D049876:Unionidae / Q000201:enzymology* / Q000235:genetics* / Q000276:immunology
chemical_list: D000890:Anti-Infective Agents; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; D009113:Muramidase
keywords: Cristaria plicata; expression pattern; lysozyme; protein characterization