Dichloromethane dehalogenase

1998 ◽  
pp. 201-204
Author(s):  
Dietmar Schomburg ◽  
Dörte Stephan
1991 ◽  
Vol 274 (2) ◽  
pp. 409-414 ◽  
Author(s):  
D J Meyer ◽  
B Coles ◽  
S E Pemble ◽  
K S Gilmore ◽  
G M Fraser ◽  
...  

Glutathione transferases (GSTs) of a novel class, which it is proposed to term Theta, were purified from rat and human liver. Two, named GST 5-5 and GST 12-12, were obtained from the rat, and one, named GST theta, was from the human. Unlike other mammalian GSTs they lack activity towards 1-chloro-2,4-dinitrobenzene and are not retained by GSH affinity matrices. Only GST 5-5 retains full activity during purification, and its activities towards the substrates 1,2-epoxy-3-(p-nitrophenoxy)propane, p-nitrobenzyl chloride, p-nitrophenethyl bromide, cumene hydroperoxide, dichloromethane and DNA hydroperoxide are 185, 86, 67, 42, 11 and 0.03 mumol/min per mg of protein respectively. Earlier preparations of GST 5-5 or GST E were probably a mixture of GST 5-5 and GST 12-12, which was largely inactive, and may also have been contaminated by less than 1% with another GSH peroxidase of far greater activity. Partial analysis of primary structure shows that subunits 5, 12 and theta are related to each other, particularly at the N-terminus, where 25 of 27 residues are identical, but have little relationship to the Alpha, Mu and Pi classes of mammalian GSTs. They do, however, show some relatedness to subunit I of Drosophila melanogaster [Toung, Hsieh & Tu (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 31-35] and the dichloromethane dehalogenase of Methylobacterium DM4 [La Roche & Leisinger (1990) J. Bacteriol, 172, 164-171].


2000 ◽  
Vol 182 (19) ◽  
pp. 5433-5439 ◽  
Author(s):  
Martin F. Kayser ◽  
Michael T. Stumpp ◽  
Stéphane Vuilleumier

ABSTRACT Methylobacterium dichloromethanicum DM4 grows with dichloromethane as the unique carbon and energy source by virtue of a single enzyme, dichloromethane dehalogenase–glutathioneS-transferase. A mutant of the dichloromethane-degrading strain M. dichloromethanicum DM4, strain DM4-1445, was obtained by mini-Tn5 transposon mutagenesis that was no longer able to grow with dichloromethane. Dichloromethane dehalogenase activity in this mutant was comparable to that of the wild-type strain. The site of mini-Tn5 insertion in this mutant was located in the polA gene encoding DNA polymerase I, an enzyme with a well-known role in DNA repair. DNA polymerase activity was not detected in cell extracts of the polA mutant. Conjugation of a plasmid containing the intact DNA polymerase I gene into thepolA mutant restored growth with dichloromethane, indicating that the polA gene defect was responsible for the observed lack of growth of this mutant with dichloromethane. Viability of the DM4-1445 mutant was strongly reduced upon exposure to both UV light and dichloromethane. The polA′-lacZtranscriptional fusion resulting from mini-Tn5 insertion was constitutively expressed at high levels and induced about twofold after addition of 10 mM dichloromethane. Taken together, these data indicate that DNA polymerase I is essential for growth of M. dichloromethanicum DM4 with dichloromethane and further suggest an important role of the DNA repair machinery in the degradation of halogenated, DNA-alkylating compounds by bacteria.


Microbiology ◽  
2000 ◽  
Vol 146 (11) ◽  
pp. 2967-2975 ◽  
Author(s):  
Gareth J. Evans ◽  
Gail P. Ferguson ◽  
Ian R. Booth ◽  
Stéphane Vuilleumier

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