Biomaterial Database

Arthropod and mollusk defensins--evolution by exon-shuffling. 2003

Oren Froy, and Michael Gurevitz

Institute of Biochemistry, Food Science and Nutrition, Faculty of Agricultural, Food and Environmental Quality, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel. orenfroy@hotmail.com

Arthropod and mollusk defensins are secreted antibacterial proteins that exhibit similarity in sequence, mode of action and structure and are expressed ubiquitously. Comparison of the gene organization of a newly cloned scorpion defensin gene, with that of other arthropods and the mussel, revealed that all exons and introns, aside from the exon encoding the mature protein, differ widely in number, size and sequence. This variability suggests that the exon encoding the mature defensin has undergone exon-shuffling and integrated downstream of unrelated leader sequences during evolution. Unlike other exon-shuffling events, in which modules are added into existing proteins, arthropod and mollusk defensins represent the first instance of exon-shuffling of autonomous modules.

UI	MeSH Term	Description	Entries
D008974	Mollusca	A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.	Molluscs,Mollusks,Mollusc,Molluscas,Mollusk
D005091	Exons	The parts of a transcript of a split GENE remaining after the INTRONS are removed. They are spliced together to become a MESSENGER RNA or other functional RNA.	Mini-Exon,Exon,Mini Exon,Mini-Exons
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001181	Arthropods	Members of the phylum Arthropoda, composed of organisms having a hard, jointed exoskeleton and paired jointed legs. It includes the class INSECTS and the subclass ARACHNIDA, many species of which are important medically as parasites or as vectors of organisms capable of causing disease in man.	Arthropoda,Arthropod
D015321	Gene Rearrangement	The ordered rearrangement of gene regions by DNA recombination such as that which occurs normally during development.	DNA Rearrangement,DNA Rearrangements,Gene Rearrangements,Rearrangement, DNA,Rearrangement, Gene,Rearrangements, DNA,Rearrangements, Gene
D019143	Evolution, Molecular	The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.	Molecular Evolution,Genetic Evolution,Evolution, Genetic
D023082	Defensins	Family of antimicrobial peptides that have been identified in humans, animals, and plants. They are thought to play a role in host defenses against infections, inflammation, wound repair, and acquired immunity.	Defensin