title: Overview of chitin metabolism enzymes in Manduca sexta: Identification, domain organization, phylogenetic analysis and gene expression.
abstract: Chitin is one of the most abundant biomaterials in nature. The biosynthesis and degradation of chitin in insects are complex and dynamically regulated to cope with insect growth and development. Chitin metabolism in insects is known to involve numerous enzymes, including chitin synthases (synthesis of chitin), chitin deacetylases (modification of chitin by deacetylation) and chitinases (degradation of chitin by hydrolysis). In this study, we conducted a genome-wide search and analysis of genes encoding these chitin metabolism enzymes in Manduca sexta. Our analysis confirmed that only two chitin synthases are present in M. sexta as in most other arthropods. Eleven chitin deacetylases (encoded by nine genes) were identified, with at least one representative in each of the five phylogenetic groups that have been described for chitin deacetylases to date. Eleven genes encoding for family 18 chitinases (GH18) were found in the M. sexta genome. Based on the presence of conserved sequence motifs in the catalytic sequences and phylogenetic relationships, two of the M. sexta chitinases did not cluster with any of the current eight phylogenetic groups of chitinases: two new groups were created (groups IX and X) and their characteristics are described. The result of the analysis of the Lepidoptera-specific chitinase-h (group h) is consistent with its proposed bacterial origin. By analyzing chitinases from fourteen species that belong to seven different phylogenetic groups, we reveal that the chitinase genes appear to have evolved sequentially in the arthropod lineage to achieve the current high level of diversity observed in M. sexta. Based on the sequence conservation of the catalytic domains and on their developmental stage- and tissue-specific expression, we propose putative functions for each group in each category of enzymes.
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tetreau
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Cao
authors.affiliation: Boyce Thompson Institute, Cornell University, Ithaca, NY 14853-1801, USA.
authors.forename: Yun-Ru
authors.initials: YR
authors.lastname: Chen
authors.affiliation: Department of Biochemistry & Molecular Biophysics, Kansas State University, 141 Chalmers Hall, Manhattan, KS 66506, USA.
authors.forename: Subbaratnam
authors.initials: S
authors.lastname: Muthukrishnan
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Haobo
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Boyce Thompson Institute, Cornell University, Ithaca, NY 14853-1801, USA.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Blissard
authors.affiliation: Department of Biochemistry & Molecular Biophysics, Kansas State University, 141 Chalmers Hall, Manhattan, KS 66506, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kanost
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA. Electronic address: pw15@cornell.edu.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
mesh_terms: D000581:Amidohydrolases / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D002686:Chitin / Q000378:metabolism*; D002688:Chitinases / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D015870:Gene Expression; D049750:Genome, Insect; D018402:Manduca / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D017434:Protein Structure, Tertiary
chemical_list: D002686:Chitin; D002688:Chitinases; D000581:Amidohydrolases; C019866:chitin deacetylase
keywords: Chitin deacetylases; Chitin synthases; Chitinases; Lepidoptera; Phylogenetic analysis; RNA-seq; Tobacco hornworm