Regulation of aflatoxin production by Ca2+�/calmodulin-dependent protein phosphorylation and dephosphorylation

Jayashree, T. and Rao, J. P. and Subramanyam, C. (2000) Regulation of aflatoxin production by Ca2+�/calmodulin-dependent protein phosphorylation and dephosphorylation. Fems Microbiology Letters, 183 (2). pp. 215-219.

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Abstract

To elucidate Ca2�+-mediated regulation of aflatoxin production, the status of Ca2�+�/calmodulin-dependent protein phosphorylation and dephosphorylation was investigated employing toxigenic and non-toxigenic strains of Aspergillus parasiticus. Incubation of cytoplasmic extracts with [Q-32P]ATP followed by SDS-PAGE and autoradiography revealed total absence of protein phosphorylation during periods corresponding to aflatoxin production in the toxigenic strain (NRRL 2999). In contrast, protein phosphorylation was unaffected in the nontoxigenic strain (SRRC 255). Aflatoxin production in the toxigenic strain was also accompanied by enhanced (26-fold) activity of calcineurin (calmodulin-dependent protein phosphatase 2B) concomitant with a lowered (6-fold) activity of calmodulin-dependent protein kinase. In addition, the in vitro activity of Ca2�+�/calmodulin-dependent protein kinase was susceptible to dose-dependent inhibition by aflatoxin. Since calcineurin remains active in the absence of phosphorylation by calmodulin-dependent protein kinase, it is suggested that calcineurin-mediated dephosphorylation of regulatory enzymes ensures continued production of aflatoxins.

Item Type: Article
Uncontrolled Keywords: Aflatoxin, Calcium, Calcineurin, Calmodulin, Calmodulin-dependent protein kinase, Calmodulin-dependent protein phosphatase
Author Affiliation: Department of Biochemistry, University College of Science, Osmania University, Hyderabad 500 007, AP, India
Subjects: Plant Protection > Pesticides
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 09 Aug 2012 10:41
Last Modified: 09 Aug 2012 10:42
Official URL: http://dx.doi.org/10.1016/S0378-1097(99)00642-4
URI: http://eprints.icrisat.ac.in/id/eprint/7283

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