Microbial biosynthesis of halometabolites

van Pee, KH

Kh. Van Pee, Microbial biosynthesis of halometabolites, ARCH MICROB, 175(4), 2001, pp. 250-258

33

INGLESE

Review

Microbiology

ARCHIVES OF MICROBIOLOGY

0302-8933 → ACNP

175

4

2001

250 - 258

ISI

0302-8933(200104)175:4<250:MBOH>2.0.ZU;2-B

Halometabolites are compounds that are commonly found in nature and they ar e produced by many different organisms. Whereas bromometabolites can mainly be found in the marine environment, chlorometabolites are predominately pr oduced by terrestrial organisms; iodo- and fluorocompounds are only produce d infrequently. The halogen atoms are incorporated into organic compounds b y enzyme-catalyzed reactions with halide ions as the halogen source. For ov er 40 years haloperoxidases were thought to be responsible for the incorpor ation of halogen atoms into organic molecules. However, haloperoxidases lac k substrate specificity and regioselectivity. and the connection of haloper oxidases with the in vivo formation of halometabolites has never been demon strated. Recently, molecular genetic investigations showed that, at least i n bacteria, a different class of halogenases is involved in halometabolite formation. These halogenases were found to require FADH(2), which can be pr oduced from FAD and NADH by unspecific flavin reductases. In addition to FA DH(2), oxygen and halide ions (chloride and bromide) are necessary for the halogenation reaction. The FADH(2)-dependent halogenases show substrate spe cificity and regioselectivity, and their gents have been detected in many h alometabolite-producing bacteria, suggesting that this type of halogenating enzymes constitutes the major source for halometabolite formation in bacte ria and possibly also in other organisms.