Accumulation of homolanthionine and activation of a novel pathway for isoleucine biosynthesis in corynebacterium glutamicum McbR deletion strains

Kromer, Jens Olaf, Heinzle, Elmar, Schroder, Hartwig and Wittmann, Christoph (2006) Accumulation of homolanthionine and activation of a novel pathway for isoleucine biosynthesis in corynebacterium glutamicum McbR deletion strains. Journal of Bacteriology, 188 2: 609-618.


Author Kromer, Jens Olaf
Heinzle, Elmar
Schroder, Hartwig
Wittmann, Christoph
Title Accumulation of homolanthionine and activation of a novel pathway for isoleucine biosynthesis in corynebacterium glutamicum McbR deletion strains
Journal name Journal of Bacteriology   Check publisher's open access policy
ISSN 0021-9193
Publication date 2006-01
Sub-type Article (original research)
DOI 10.1128/JB.188.2.609-618.2006
Volume 188
Issue 2
Start page 609
End page 618
Total pages 10
Place of publication United States
Publisher American Society for Microbiology
Language eng
Subject 060101 Analytical Biochemistry
060104 Cell Metabolism
Abstract n the present work, the metabolic consequences of the deletion of the methionine and cysteine biosynthesis repressor protein (McbR) in Corynebacterium glutamicum, which releases almost all enzymes of methionine biosynthesis and sulfate assimilation from transcriptional regulation (D. A. Rey, A. Pühler, and J. Kalinowski, J. Biotechnol. 103:51-65, 2003), were studied. C. glutamicum ATCC 13032 {Delta}mcbR showed no overproduction of methionine. Metabolome analysis revealed drastic accumulation of a single metabolite, which was not present in the wild type. It was identified by isotopic labeling studies and gas chromatography/mass spectrometry as L-homolanthionine {S-[(3S)-3-amino-3-carboxypropyl]-L-homocysteine}. The accumulation of homolanthionine to an intracellular concentration of 130 mM in the {Delta}mcbR strain was accompanied by an elevated intracellular homocysteine level. It was shown that cystathionine-{gamma}-synthase (MetB) produced homolanthionine as a side reaction. MetB showed higher substrate affinity for cysteine (Km = 260 µM) than for homocysteine (Km = 540 µM). The cell is able to cleave homolanthionine at low rates via cystathionine-ß-lyase (MetC). This cleavage opens a novel threonine-independent pathway for isoleucine biosynthesis via 2-oxobutanoate formed by MetC. In fact, the deletion mutant exhibited an increased intracellular isoleucine level. Metabolic flux analysis of C. glutamicum {Delta}mcbR revealed that only 24% of the O-acetylhomoserine at the entry of the methionine pathway is utilized for methionine biosynthesis; the dominating fraction is either stored as homolanthionine or redirected towards the formation of isoleucine. Deletion of metB completely prevents homolanthionine accumulation, which is regarded as an important step in the development of C. glutamicum strains for biotechnological methionine production.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Australian Institute for Bioengineering and Nanotechnology Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 19 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 22 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Access Statistics: 80 Abstract Views  -  Detailed Statistics
Created: Fri, 13 Feb 2009, 09:56:33 EST by Maryanne Watson on behalf of Aust Institute for Bioengineering & Nanotechnology