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Appl. Environ. Microbiol., Apr 1995, 1180-1186, Vol 61, No. 4
TL Miller, X Chen, B Yan and S Bank
We found that general pathways for amino acid synthesis of Methanosphaera
stadtmanae, a methanogen that forms CH(inf4) from H(inf2) and methanol,
resembled those of methanogens that form CH(inf4) from CO(inf2) or from the
methyl group of acetate. We determined the incorporation of
(sup14)C-labeled CO(inf2), formate, methanol, methionine, serine, and
acetate into cell macromolecules. Labeling of amino acid carbons was
determined by solution nuclear magnetic resonance spectroscopy after growth
with (sup13)C-labeled acetate, CO(inf2), serine, and methanol. The (alpha)
and (beta) carbons of serine and alanine were formed from carboxyl and
methyl carbons of acetate, respectively, and the amino acid carboxyl groups
were formed from CO(inf2). This indicates that pyruvate was formed by
reductive carboxylation of acetate. Labeling of the methyl carbon of
methionine indicated that the major route of synthesis was from the
hydroxymethyl carbon of serine that arises from the methyl carbon of
acetate. Methanol was a minor source of the methyl of methionine.
Unambiguous assignment was made of the sources of all carbons of histidine.
Labeling of the histidine 7 position ((epsilon) carbon) was consistent with
formation from the C-2 of the purine ring of ATP and the origin of the C-2
from a formyl unit derived from the hydroxymethyl carbon of serine.
Copyright © 1995, American Society for Microbiology
Solution (sup13)C Nuclear Magnetic Resonance Spectroscopic Analysis of the Amino Acids of Methanosphaera stadtmanae: Biosynthesis and Origin of One-Carbon Units from Acetate and Carbon Dioxide
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, New York 12201-0509, and Department of Chemistry, State University of New York at Albany, Albany, New York 12222
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