Carbonyl reducing 17 beta-hydroxysteroid dehydrogenase from the filamentous fungus Cochliobolus lunatus.

Abstract

Hydroxysteroid dehydrogenases (HSDs) which catalyse reversible oxidoreduction of ketosteroids and their respective hydroxysteroids have often been found to have additional substrate specificities towards nonsteroidal ketones, aldehydes and quinones (Maser, 1995). In mammals, such pluripotent enzymes were found in peripheral (Boutin, 1986; Hara et al., 1986;Hara et al. 1986a; Sawada et al., 1988; Klein et al., 1992; Maser and Bannenberg, 1994; Deyashiki et al., 1994; Ohara et al., 1994; Maser, 1995; Oppermann et al., 1995) as well as steroidogenic tissues (Tanaka et al., 1992; Nakajin et al., 1994; Jarabak et al., 1996). They were supposed to be involved in the detoxification of xenobiotic carbonyl compounds in addition to their role in the metabolism of endogenous steroids, prostaglandins, and quinones (Maser and Bannenberg, 1994; Oppermann et al., 1995). In microorganisms it has been shown for some bacterial HSDs that they have the versatility to accept steroidal as well as non-steroidal substrates (Oppermann et al., 1993; Maser, 1995). On the other hand, pluripotency of fungal HSD has not been discovered. Recently, 17β-hydroxysteroid dehydrogenase (17β-HSD) from the fungus Cochliobolus lunatus was purified and some of its molecular and kinetic properties were characterized (Lanisnik Rižner et al., 1996). In the present paper we provide further characterization of this enzyme and also some data indicating that it is a fungal enzyme with carbonyl reductase activity.