Inhibition of juvenile hormone III biosynthesis in cockroach corpora allata by interference with the S‐adenosylmethionine‐dependent transmethylation

Abstract

The synthesis of juvenile hormone-Ill by corpora allata of the cockroach Diploptera punctata is dependent under in vitro conditions upon a supply of exogenous methionine. Radiolabelled S-adenosylmethionine was identified by HPLC in extracts of corpora allata incubated with either [methyl-3H]methionine or 13%]methionine. Juvenile hormone (JH) synthesis by intact glands in vitro was inhibited by cycloleucine and selenomethionine, but this inhibition could be relieved by increasing the concentration of methionine. S-adenosylhomocysteine or sinefungin had little or no inhibitory effect on J H synthesis by intact glands, but 5'-deoxy-5'-methylthioadenosine was inhibitory. Adenosine and homocysteine synergistically inhibited J H synthesis. These results show that JH-Ill synthesis by intact glands can be inhibited by interfering with the S-adenosylmethionine-dependent transmethylation, and suggest that the product and inhibitor of that reaction, S-adenosylhomocysteine, is rapidly hydrolyzed to adenosine and homocysteine in the corpora allata. Key words: juvenile hormone synthesis, S-adenosylmethionine, S-adenosylhomocysteine hydrolase INTRODUCTIONThe known insect juvenile hormones are characterized by an important methyl ester function. Early work on JH* showed that this function is essen-

Comparative genomics of insect juvenile hormone biosynthesis☆

“…Significantly, we found ESTs in both cockroach and the two mosquito libraries for the enzyme synthesizing AdoMet, adenosyl transferase, on one hand, and for adenosine homocysteinase on the other hand. Adenosyl homocysteinase catalyzes the degradation of AdoHcy into homocysteine and adenosine and thus removes AdoHcy, a known inhibitor of the methylation reaction (Feyereisen and Farnsworth, 1987a). Further, ESTs for adenosine kinase were also identified in both cockroach and the two mosquito libraries.…”

Inhibition of insect juvenile hormone synthesis by phorbol 12‐myristate 13‐acetate

“…In the viviparous cockroach, Diploptera punctata, an allatostatin originating in the brain reaches the corpora allata via nervous connections where it can be released experimentally in response to high-K + treatment [2]. This inhibitory peptide may utilize cAMP as second messenger, because it causes an elevation in cAMP levels in the corpora aUata [2] and its effects can be mimicked by forskolin [3]. In addition to cAMP [3,4], calcium has been implicated as an intracellular regulator of JH III synthesis in D. punctata [5].…”

“…This inhibitory peptide may utilize cAMP as second messenger, because it causes an elevation in cAMP levels in the corpora aUata [2] and its effects can be mimicked by forskolin [3]. In addition to cAMP [3,4], calcium has been implicated as an intracellular regulator of JH III synthesis in D. punctata [5].…”