Complement factor D homolog involved in the alternative complement pathway of rock bream (Oplegnathus fasciatus): Molecular and functional characterization and immune responsive mRNA expression analysis.
The complement system serves conventional role in the innate defense against common invading pathogens. Complement factor D (CfD) is vital to alternative complement pathway activation in cleaving complement factor B. This catalytic reaction forms the alternative C3 convertase that is crucial for complement-mediated pathogenesis. In this study, rock bream (Oplegnathus fasciatus) CfD (OfCfD) was characterized and OfCfD mRNA expression was investigated. OfCfD encodes 277 amino acids (aa) for a 30-kDa polypeptide. A domain analysis of the deduced OfCfD aa sequence showed a single serine protease trypsin superfamily domain, a serine active region, three active sites, and three substrate-binding sites. Pairwise sequence comparisons indicated that OfCfD has the highest identity (84.5%) with Oreochromis niloticus CfD. The phylogenetic tree revealed a common ancestral origin of CfD members, with fish CfD distinct from other vertebrate orthologs. The structural arrangement of the OfCfD gene (2451 bp) contained five exons interrupted by four introns. A spatial transcriptional analysis indicated that OfCfD transcripts constitutively expressed in all of the examined rock bream tissues, and that they were highest in the spleen and liver. In addition, OfCfD transcripts were immunologically upregulated by lipopolysaccharide (LPS) (12 h p.i.), Streptococcus iniae (12 h p.i.), rock bream iridovirus (RBIV) (6-12 h p.i.), and poly I:C (6 h p.i.) in spleen tissue. OfCfD is a trypsin protease and its recombinant protein showed strong protease activity similar to that of trypsin, indicating its catalytic function in the alternative pathway. Together, our findings suggest that OfCfD might be involved in immune responses in rock bream.
Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
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Godahewa
Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
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Perera
Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
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Bathige
Biotechnology Research Division, National Institute of Fisheries Science, 408-1 Sirang-ri, Gijang-up, Gijang-gun, Busan, 46083, Republic of Korea.
Bo-Hye
BH
Nam
Genetics & Breeding Research Center, National Institute of Fisheries Science, Geoje, 53334, Republic of Korea. Electronic address: jae9noh@korea.kr.
Jae Koo
JK
Noh
Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea. Electronic address: jehee@jejunu.ac.kr.
Jehee
J
Lee
D000818:Animals; D011416:Complement Factor D / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003170:Complement Pathway, Alternative / Q000187:drug effects / Q000235:genetics*; D004266:DNA Virus Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology*; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects; D007497:Iridoviridae / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D010473:Perciformes; D011070:Poly I-C / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment / Q000662:veterinary; D013154:Spleen / Q000276:immunology / Q000382:microbiology / Q000821:virology; D013290:Streptococcal Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary; D000070058:Streptococcus iniae / Q000502:physiology
D018076:DNA, Complementary; D029941:Fish Proteins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011416:Complement Factor D; D011070:Poly I-C
Alternative pathway; Complement; Genome; Immune challenge; Protease activity