tailieunhanh - Báo cáo Y học: Function and cellular localization of farnesoic acid O -methyltransferase (FAMeT) in the shrimp, Metapenaeus ensis

The isoprenoid methyl farnesoate (MF) has been implicated in the regulation of crustacean development and reproduction in conjunction with eyestalk molt inhibiting hormones and ecdysteroids. Farnesoic acid O-methyltransferase (FAMeT) catalyzes the methylation of farnesoic acid (FA) to produce MF in the terminal step of MF synthesis. We have previously cloned and characterized the shrimp FAMeT. In the present study, recombinant FAMeT (rFAMeT) was produced for bioassay and antiserum generation. FAMeT is widely distributed in shrimp tissues with the highest concentration observed in the ventral nerve cord. Interestingly, an additional larger protein in the eyestalk also showed immunoreactivity to anti-FAMeT serum | Eur. J. Biochem. 269 3587-3595 2002 FEBS 2002 doi Function and cellular localization of farnesoic acid ớ-methyltransferase FAMeT in the shrimp Metapenaeus ensis Y. I. N. Silva Gunawardene1 S. S. Tobe2 W. G. Bendena3 B. K. C. Chow1 K. J. Yagi2 and . Chan1 1 Department of Zoology The University of Hong Kong Pokfulam Road Hong Kong China department of Zoology University of Toronto Ontario Canada 3Department of Biology Queen s University Kingston Ontario Canada The isoprenoid methyl farnesoate MF has been implicated in the regulation of crustacean development and reproduction in conjunction with eyestalk moll ínhibiiíng hormones and ecdysteroids. Farnesoic acid O-methyl-transferase FAMeT catalyzes the methylation of farne-soic acid FA to produce MF in the terminal step of MF synthesis. We have previously cloned and characterized the shrimp FAMeT. In the present study recombinant FAMeT rFAMeT was produced for bioassay and antiserum generation. FAMeT is widely distributed in shrimp tissues with the highest concentration observed in the ventral nerve cord. Interestingly an additional larger protein in the eyestalkalso showed immunoreactivity to anti-FAMeT serum. FAMeT was localized in the neurosecretory cells of the X-organ-sinus gland complex of the eyestalk. As shown by RT-PCR FAMeT mRNA is constitutively expressed throughout the molt cycle in the eyestalkand the ventral nerve cord. To show that our cloned gene product had FAMeT activity we demonstrated that expressed rFAMeT gene product catalyzed the conversion of FA to MF in a radiochemical assay. The ubiquitous distribution of FAMeT suggests that this enzyme is involved in physiological processes in addition to gametogenesis oocyte maturation and development and metamorphosis of the shrimp. We hypothesize that FAMeT directly or indirectly through MF modulates the reproduction and growth of crustaceans by interacting with the eyestalkneuropeptides as a consequence of its presence .