Endogenous cellulase enzymes in the stick insect (Phasmatodea) gut.
High cellulase (endo-beta-1,4-glucanase) activity was detected in the anterior midgut of the walking stick (Phasmatodea) Eurycantha calcarata. The enzyme was isolated and analyzed via mass spectrometry. RT-PCR revealed two endoglucanase genes, EcEG1 and EcEG2. Mascot analysis of the purified enzyme confirms it to be the product of gene EcEG1. Homologous cDNAs were also isolated from a distantly related species, Entoria okinawaensis, suggesting a general distribution of cellulase genes in phasmids. Phasmid cellulases showed high homology to endogenously-produced glycoside hydrolase family 9 (GH9) endoglucanases from insects, especially to those of termites, cockroaches, and crickets. The purified E. calcarata enzyme showed clear antigency against an anti-serum for termite GH9 cellulase, which, together with the sequence homology, further suggests an endogenous origin of the enzyme. This discovery suggests a possible nutritive value for cellulose in the leaf-feeding phasmids, unlike in herbivorous Lepidoptera.
Department of Entomology and Nematology, University of California Davis, 1 Shields Ave., Davis, CA 95616, USA. Electronic address: mshelomi@ucdavis.edu.
Matan
M
Shelomi
Insect Mimetics Research Unit, National Institute of Agrobiological Sciences, Owashi 1-2, Tsukuba, Ibaraki 305-8634, Japan. Electronic address: hinabe@affrc.go.jp.
Hirofumi
H
Watanabe
Insect Mimetics Research Unit, National Institute of Agrobiological Sciences, Owashi 1-2, Tsukuba, Ibaraki 305-8634, Japan.
Gaku
G
Arakawa
D000595:Amino Acid Sequence; D000818:Animals; D044644:Endo-1,3(4)-beta-Glucanase / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000201:enzymology; D007313:Insecta / Q000201:enzymology*; D008297:Male; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D011134:Polysaccharides; D044644:Endo-1,3(4)-beta-Glucanase
Cellulase; Digestion; Endoglucanase; Entoria okinawaensis; Eurycantha calcarata; Phasmatodea