Characterization of the gene encoding component C3 of the complement system from the spider Loxosceles laeta venom glands: Phylogenetic implications.
A transcriptome analysis of the venom glands of the spider Loxosceles laeta, performed by our group, in a previous study (Fernandes-Pedrosa et al., 2008), revealed a transcript with a sequence similar to the human complement component C3. Here we present the analysis of this transcript. cDNA fragments encoding the C3 homologue (Lox-C3) were amplified from total RNA isolated from the venom glands of L. laeta by RACE-PCR. Lox-C3 is a 5178 bps cDNA sequence encoding a 190kDa protein, with a domain configuration similar to human C3. Multiple alignments of C3-like proteins revealed two processing sites, suggesting that Lox-C3 is composed of three chains. Furthermore, the amino acids consensus sequences for the thioester was found, in addition to putative sequences responsible for FB binding. The phylogenetic analysis showed that Lox-C3 belongs to the same group as two C3 isoforms from the spider Hasarius adansoni (Family Salcitidae), showing 53% homology with these. This is the first characterization of a Loxosceles cDNA sequence encoding a human C3 homologue, and this finding, together with our previous finding of the expression of a FB-like molecule, suggests that this spider species also has a complement system. This work will help to improve our understanding of the innate immune system in these spiders and the ancestral structure of C3.
Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.
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DT
Myamoto
Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.
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Pidde-Queiroz
Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.
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Pedroso
Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.
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Gonçalves-de-Andrade
Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff, UK.
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van den Berg
Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil. Electronic address: denise.tambourgi@butantan.gov.br.
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Tambourgi
D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics*; D001483:Base Sequence; D003176:Complement C3 / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D005088:Exocrine Glands / Q000276:immunology; D005260:Female; D010727:Phosphoric Diester Hydrolases; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013111:Spider Venoms; D013112:Spiders / Q000235:genetics* / Q000276:immunology
D060829:Arthropod Proteins; D003176:Complement C3; D018076:DNA, Complementary; D013111:Spider Venoms; C055161:loxosceles venom; D010727:Phosphoric Diester Hydrolases
C3; Complement system; Gene; Loxosceles; Phylogenetic analysis; Spider