title: Domain organization and phylogenetic analysis of the chitinase-like family of proteins in three species of insects.
abstract: A bioinformatics-based investigation of three insect species with completed genome sequences has revealed that insect chitinase-like proteins (glycosylhydrolase family 18) are encoded by a rather large and diverse group of genes. We identified 16, 16 and 13 putative chitinase-like genes in the genomic databases of the red flour beetle, Tribolium castaneum, the fruit fly, Drosophila melanogaster, and the malaria mosquito, Anopheles gambiae, respectively. Chitinase-like proteins encoded by this gene family were classified into five groups based on phylogenetic analyses. Group I chitinases are secreted proteins that are the most abundant such enzymes in molting fluid and/or integument, and represent the prototype enzyme of the family, with a single copy each of the catalytic domain and chitin-binding domain (ChBD) connected by an S/T-rich linker polypeptide. Group II chitinases are unusually larger-sized secreted proteins that contain multiple catalytic domains and ChBDs. Group III chitinases contain two catalytic domains and are predicted to be membrane-anchored proteins. Group IV chitinases are the most divergent. They usually lack a ChBD and/or an S/T-rich linker domain, and are known or predicted to be secreted proteins found in gut or fat body. Group V proteins include the putative chitinase-like imaginal disc growth factors (IDGFs). In each of the three insect genomes, multiple genes encode group IV and group V chitinase-like proteins. In contrast, groups I-III are each represented by only a singe gene in each species.
authors.affiliation: Department of Biochemistry, Kansas State University, Manhattan, KS 66506, USA.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Zhu
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Arakane
authors.forename: Debarshi
authors.initials: D
authors.lastname: Banerjee
authors.forename: Richard W
authors.initials: RW
authors.lastname: Beeman
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Kramer
authors.forename: Subbaratnam
authors.initials: S
authors.lastname: Muthukrishnan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D002688:Chitinases / Q000235:genetics*; D002874:Chromosome Mapping; D030561:Databases, Nucleic Acid; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics; D049750:Genome, Insect; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014231:Tribolium / Q000201:enzymology* / Q000235:genetics
chemical_list: D002688:Chitinases