title: Five hepatopancreatic and one epidermal chitinases from a pandalid shrimp (Pandalopsis japonica): cloning and effects of eyestalk ablation on gene expression.
abstract: Six cDNAs encoding chitinase proteins in Pandalopsis japonica were isolated by using polymerase chain reaction (PCR) cloning methods and bioinformatic analysis of expressed sequence tags (ESTs). The cDNAs, designated Pj-Cht1, 2, 3A, 3B, 3C, and 4, encoded proteins ranging from 388 to 607 amino acid residues in length (43.61-67.62kDa) and displayed a common structural organization: an N-terminal catalytic domain, a Thr/Pro-rich linker region, and either 0 (Pj-Cht2, 3A), 1 (Pj-Cht1, 3B, and 3C), or 2 (Pj-Cht4) C-terminal chitin-binding domain(s) (CBD). Pj-Cht1 and 2 lacked the 5' end of the open reading frame (ORF); the other Pj-Chts contained the complete ORF. All known decapod crustacean chitinases were segregated into at least four groups based on phylogenetic analysis and domain organization. Group 1 chitinases, represented by Pj-Cht1, were most closely related to insect group I chitinases and may function in the digestion of the peritrophic membrane. Group 2 chitinases including Pj-Cht2 show different domain organizations and pI value from other chitinases and appear to function in degradation of the old exoskeleton during the premolt period. Group 3 chitinases, represented by Pj-Cht3A, 3B, and 3C, may function in digestion of chitin-containing food and defense against pathogens. Group 4 chitinases, represented by Pj-Cht4, have two CBDs and their functions are unknown. Five Pj-Chts (Pj-Cht1, 3A, 3B, 3C, and 4) are expressed in the hepatopancreas and intestine, whereas Pj-Cht2 is expressed in epidermis and SG/XO complex suggesting crustacean chitinases can be classified into two groups (hepatopancreatic and epidermal) based on the expression profile. Eyestalk ablation (ESA) down-regulated the hepatopancreatic chitinase expression (Pj-Cht1, 3A, and 3C); Pj-Cht3B expression was not significantly affected by ESA. By contrast, mRNA levels of Pj-Cht2 were significantly upregulated in 7days post-ESA. Pj-Cht4 mRNA levels were too low for measurement with quantitative polymerase chain reaction. ESA had no significant effect on chitinase expression in the intestine. These data indicate that Pj-Cht1, 3A, 3B, 3C, and 4 are hepatopancreatic chitinases that may function in the digestion of ingested chitin and the modification of peritrophic membrane in the intestine. By contrast, epidermal chitinase, Pj-Cht2 may play a role in chitin metabolism during molt cycle as shown in other crustacean group 2 chitinases.
authors.affiliation: Department of Marine Biology, Pukyong National University, Busan 608-737, South Korea.
authors.forename: Umme
authors.initials: U
authors.lastname: Salma
authors.forename: Md Hasan
authors.initials: MH
authors.lastname: Uddowla
authors.forename: Meesun
authors.initials: M
authors.lastname: Kim
authors.forename: Jong Min
authors.initials: JM
authors.lastname: Kim
authors.forename: Bo Kwang
authors.initials: BK
authors.lastname: Kim
authors.forename: Hae-Ja
authors.initials: HJ
authors.lastname: Baek
authors.forename: Hyun
authors.initials: H
authors.lastname: Park
authors.forename: Donald L
authors.initials: DL
authors.lastname: Mykles
authors.forename: Hyun-Woo
authors.initials: HW
authors.lastname: Kim
mesh_terms: D055011:Ablation Techniques; D000595:Amino Acid Sequence; D000818:Animals; D002688:Chitinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004817:Epidermis / Q000201:enzymology*; D005123:Eye / Q000378:metabolism* / Q000473:pathology*; D005786:Gene Expression Regulation; D015971:Gene Expression Regulation, Enzymologic; D043143:Hepatopancreas / Q000201:enzymology*; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D033542:Pandalidae / Q000201:enzymology / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment; D009626:Terminology as Topic
chemical_list: D018076:DNA, Complementary; D002688:Chitinases