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Isolation of ftsI and murE genes involved in peptidoglycan synthesis from Corynebacterium glutamicum
C D Wijayarathna1, M Wachi, K Nagai
1Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan.
Abstract:
Corynebacterium glutamicum is known to excrete large amounts of L-glutamic acid upon treatment by penicillin. However, the mechanism of L-glutamate overproduction by penicillin treatment is still unknown. A 5.3-kb HindIII fragment was isolated by directly introducing the C. glutamicum (Brevibacterium lactofermentum) ATCC 13869 gene library into the temperature-sensitive Escherichia coli murE mutant and selecting temperature resistant clones. Two open reading frames (ORFs) were found in this fragment: (1) murE, encoding UDP-N-acetylmuramoyl-L-alanyl-D-glutamate:meso-diaminopimelate ligase, and (2)ftsI, encoding septum-peptidoglycan synthetase, one of the targets of penicillin (penicillin-binding protein 3). Both ORFs were involved in peptidoglycan synthesis. Proteins were synthesized from the C. glutamicum murE and ftsI genes, 55 kDa and 73 kDa respectively, in an in vitro protein synthesis system, using E. coli S30 extracts.
Insights
Penicillin treatment enhances L-glutamic acid excretion in Corynebacterium glutamicum. Researchers identified two key genes, murE and ftsI, involved in peptidoglycan synthesis, potentially explaining this overproduction mechanism.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Corynebacterium glutamicum is known for high L-glutamic acid production.
- Penicillin treatment induces overproduction, but the mechanism remains unclear.
Purpose of the Study:
- To elucidate the molecular mechanism behind penicillin-induced L-glutamate overproduction in C. glutamicum.
Main Methods:
- A gene library from C. glutamicum was introduced into a temperature-sensitive Escherichia coli murE mutant.
- Temperature-resistant clones were selected to identify relevant genes.
- Open reading frames (ORFs) were analyzed, and proteins were synthesized in vitro.
Main Results:
- A 5.3-kb DNA fragment containing two ORFs, murE and ftsI, was isolated.
- Both murE and ftsI are involved in peptidoglycan synthesis.
- The C. glutamicum murE and ftsI genes encode proteins of 55 kDa and 73 kDa, respectively.
Conclusions:
- The identified murE and ftsI genes, crucial for peptidoglycan synthesis, are implicated in the L-glutamate overproduction pathway in C. glutamicum.
- Further research into these genes may reveal novel strategies for enhancing amino acid production.