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Clues from a halophilic methanogen about aromatic amino acid biosynthesis in archaebacteria

Clues from a halophilic methanogen about aromatic amino acid biosynthesis in archaebacteria 203 160 160 6 6 R. S. Fischer C. A. Bonner D. R. Boone R. A. Jensen Department of Microbiology and Cell Science University of Florida 3103 McCarty Hall 32611 Gainesville FL USA Oregon Institute of Science and Technology 19600 Northwest Von Neumann Drive 97006-1999 Beaverton OR USA Abstract Extensive diversity in features of aromatic amino acid biosynthesis and regulation has become recognized in eubacteria, but almost nothing is known about the extent to which such diversity exists within the archaebacteria. Methanohalophilus mahii , a methylotrophic halophilic methanogen, was found to synthesize l -phenylalanine and l -tyrosine via phenylpyruvate and 4-hydroxyphenylpyruvate, respectively. Enzymes capable of using l -arogenate as substrate were not found. Prephenate dehydrogenase was highly sensitive to feedback inhibition by l -tyrosine and could utilize either NADP + (preferred) or NAD + as cosubstrate. Tyrosine-pathway dehydrogenases having the combination of narrow specificity for a cyclohexadienyl substrate but broad specificity for pyridine nucleotide cofactor have not been described before. The chorismate mutase enzyme found is a member of a class which is insensitive to allosteric control. The most noteworthy character state was prephenate dehydratase which proved to be subject to multimetabolite control by feedback inhibitor ( l -phenylalanine) and allosteric activators ( l -tyrosine, l -tryptophan, l -leucine, l -methionine and l -isoleucine). This interlock type of prephenate dehydratase, also known to be broadly distributed among the gram-positive lineage of the eubacteria, was previously shown to exist in the extreme halophile, Halobacterium vallismortis . The results are consistent with the conclusion based upon 16S rRNA analyses that Methanomicrobiales and the extreme halophiles cluster together. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Microbiology Springer Journals

Clues from a halophilic methanogen about aromatic amino acid biosynthesis in archaebacteria

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Publisher
Springer Journals
Copyright
Copyright © 1993 by Springer-Verlag
Subject
Life Sciences; Biotechnology; Biochemistry, general; Cell Biology; Ecology; Microbial Ecology; Microbiology
ISSN
0302-8933
eISSN
1432-072X
DOI
10.1007/BF00245304
Publisher site
See Article on Publisher Site

Abstract

203 160 160 6 6 R. S. Fischer C. A. Bonner D. R. Boone R. A. Jensen Department of Microbiology and Cell Science University of Florida 3103 McCarty Hall 32611 Gainesville FL USA Oregon Institute of Science and Technology 19600 Northwest Von Neumann Drive 97006-1999 Beaverton OR USA Abstract Extensive diversity in features of aromatic amino acid biosynthesis and regulation has become recognized in eubacteria, but almost nothing is known about the extent to which such diversity exists within the archaebacteria. Methanohalophilus mahii , a methylotrophic halophilic methanogen, was found to synthesize l -phenylalanine and l -tyrosine via phenylpyruvate and 4-hydroxyphenylpyruvate, respectively. Enzymes capable of using l -arogenate as substrate were not found. Prephenate dehydrogenase was highly sensitive to feedback inhibition by l -tyrosine and could utilize either NADP + (preferred) or NAD + as cosubstrate. Tyrosine-pathway dehydrogenases having the combination of narrow specificity for a cyclohexadienyl substrate but broad specificity for pyridine nucleotide cofactor have not been described before. The chorismate mutase enzyme found is a member of a class which is insensitive to allosteric control. The most noteworthy character state was prephenate dehydratase which proved to be subject to multimetabolite control by feedback inhibitor ( l -phenylalanine) and allosteric activators ( l -tyrosine, l -tryptophan, l -leucine, l -methionine and l -isoleucine). This interlock type of prephenate dehydratase, also known to be broadly distributed among the gram-positive lineage of the eubacteria, was previously shown to exist in the extreme halophile, Halobacterium vallismortis . The results are consistent with the conclusion based upon 16S rRNA analyses that Methanomicrobiales and the extreme halophiles cluster together.

Journal

Archives of Microbiology – Springer Journals

Published: Dec 1, 1993

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