Previous Article | Next Article ![]()
Applied and Environmental Microbiology, August 1998, p. 2831-2835, Vol. 64, No. 8
Institut de Recherche en Biologie
Végétale, Université de Montréal, Montreal,
Quebec, Canada H1X 2B2
Received 22 December 1997/Accepted 4 June 1998
Many wood-rotting fungi, including Phellinus pomaceus,
produce chloromethane (CH3Cl). P. pomaceus can
be cultured in undisturbed glucose mycological peptone liquid medium to
produce high amounts of CH3Cl. The biosynthesis of
CH3Cl is catalyzed by a methyl chloride transferase (MCT),
which appears to be membrane bound. The enzyme is labile upon removal
from its natural location and upon storage at low temperature in its
bound state. Various detergents failed to solubilize the enzyme in
active form, and hence it was characterized by using a membrane
fraction. The enzyme had a sharp pH optimum between 7 and 7.2. Its
apparent Km for Cl
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Biochemical Characterization of Chloromethane
Emission from the Wood-Rotting Fungus Phellinus
pomaceus

(ca. 300 mM)
was much higher than that for I
(250 µM) or
Br
(11 mM). A comparison of these
Km values to the relative in vivo methylation
rates for different halides suggests that the real Km for Cl
may be much lower, but
the calculated value is high because the CH3Cl produced is
used immediately in a coupled reaction. Among various methyl donors
tested, S-adenosyl-L-methionine (SAM) was the
only one that supported significant methylation by MCT. The reaction
was inhibited by S-adenosyl-L-homocysteine, an
inhibitor of SAM-dependent methylation, suggesting that SAM is the
natural methyl donor. These findings advance our comprehension of a
poorly understood metabolic sector at the origin of biogenic emissions of halomethanes, which play an important role in atmospheric chemistry.
*
Corresponding author. Mailing address: Institut de
Recherche en Biologie Végétale, Université de
Montréal, 4101, rue Sherbrooke est, Montreal, Quebec, Canada H1X
2B2. Phone: (514) 872-0272. Fax: (514) 872-9406. E-mail:
sainih{at}ere.umontreal.ca.
Present address: Laboratoire d'Immunologie, Institut de Recherches
Cliniques de Montréal, Montreal, Quebec, Canada H2W 1R7.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»