title: First report of invertebrate Mx: cloning, characterization and expression analysis of Mx cDNA in disk abalone (Haliotis discus discus).
abstract: Myxovirus resistance (Mx) protein is one of the most studied antiviral proteins. It is induced by the type I interferon system (IFN alpha/beta) in various vertebrates, but its expression has not been identified or characterized in mollusks or other multi-cellular invertebrates to date. In this study, we isolated the Mx gene from a disk abalone (Haliotis discus discus) normalized cDNA library. Mx cDNA was sequenced, cloned and compared to other known Mx proteins. The full-length 1664 bp of abalone Mx cDNA contained a 1533-bp open reading frame that codes for 511 amino acids. Within the coding sequence of abalone Mx, characteristic features were found, such as a tripartite guanosine-5'-triphosphate (GTP)-binding motif and a dynamin family signature. In addition, leucine residues in the C-terminal region displayed a special leucine domain at L(468), L(475), L(489) and L(510), suggesting that abalone Mx may have a similar oligomerization function as other leucine zipper motifs. Abalone Mx protein exhibited 44% amino acid similarity with channel catfish Mx1, rainbow trout Mx2 and Atlantic halibut Mx. Abalones were injected intramuscularly with the known IFN inducer poly I:C and RT-PCR was performed for Mx mRNA analysis. The results showed enhanced Mx expression in abalone gill and digestive tissues 24h as well as 48 h after injection of poly I:C. Mx mRNA was expressed in gill, digestive gland, mantle and foot tissues in healthy abalone, suggesting that the basal level of Mx expressed is tissue-specific. There is no known Mx protein closely related to abalone Mx according to phylogenetic analysis. Abalone Mx may have diverged from a common gene ancestor of fish and mammalian Mx proteins, since abalone Mx showed high similarity in terms of conserved tripartite GTP-binding, dynamin family signature motifs and poly I:C enhancement of Mx mRNA expression.
authors.affiliation: Department of Marine Biotechnology, College of Ocean Science, Cheju National University, 66 Jejudaehakno, Ara-dong, Jeju, Jeju-Do 690-756, Republic of Korea.
authors.forename: Mahanama
authors.initials: M
authors.lastname: De Zoysa
authors.forename: Hyun-Sil
authors.initials: HS
authors.lastname: Kang
authors.forename: Young-Bo
authors.initials: YB
authors.lastname: Song
authors.forename: Youngheun
authors.initials: Y
authors.lastname: Jee
authors.forename: Young-Don
authors.initials: YD
authors.lastname: Lee
authors.forename: Jehee
authors.initials: J
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D049851:Gastropoda / Q000235:genetics*; D008969:Molecular Sequence Data; D064547:Myxovirus Resistance Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D064547:Myxovirus Resistance Proteins; D019204:GTP-Binding Proteins