Two different types of dehalogenases, LinA and LinB, involved in gamma-hexachlorocyclohexane degradation in Sphingomonas paucimobilis UT26 are localized in the periplasmic space without molecular processing

gamma-Hexachlorocyclohexane (gamma-HCH) is one of several highly chlorinate d insecticides that cause serious environmental problems. The cellular prot eins of a gamma-HCH-degrading bacterium, Sphingomonas paucimobilis UT26, we re fractionated into periplasmic, cytosolic, and membrane fractions after o smotic shock. Most of two different types of dehalogenase, LinA (gamma-hexa chlorocyclohexane dehydrochlorinase) and LinB (1,3,4,6-tetrachloro-1,4-cycl ohexadiene halidohydrolase), that are involved in the early steps of gamma- HCH degradation in UT26 was detected in the periplasmic fraction and had no t undertaken molecular processing. Furthermore, immunoelectron microscopy c learly showed that LinA and LinB are periplasmic proteins. LinA and LinB bo th lack a typical signal sequence for export, so they may be secreted into the periplasmic space via a hitherto unknown mechanism.