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A second lysine-specific serine protease from Lysobacter sp. strain IB-9374
Shigeru Chohnan1, Kentaro Shiraki, Kiyonobu Yokota
1College of Agriculture, Ibaraki University, 3-21-1 Chu-ou, Ami, Ibaraki 300-0393, Japan. masaki@mx.ibaraki.ac.jp
Journal of Bacteriology
|July 21, 2004
Summary
Researchers discovered a new lysyl endopeptidase gene, lepB, in Lysobacter. This gene encodes an enzyme (LepB) that is an isozyme of LepA, showing similar structure but lower activity and stability.
Area of Science:
- Microbiology
- Molecular Biology
- Enzymology
Background:
- Lysobacter harbors a highly active lysyl endopeptidase encoded by the lepA gene.
- A second, distinct lysyl endopeptidase gene, lepB, was identified upstream of lepA in Lysobacter genomic DNA.
Purpose of the Study:
- To characterize the newly discovered lysyl endopeptidase gene (lepB) and its protein product (LepB).
- To compare the biochemical and structural properties of LepB with the previously identified LepA.
Main Methods:
- Gene sequencing and analysis of Lysobacter genomic DNA.
- Overexpression of lepB in Escherichia coli and protein refolding.
- Purification and biochemical characterization of the LepB enzyme.
- Amino acid sequence alignment and molecular modeling.
Main Results:
- The lepB gene encodes a 678-amino acid precursor protein, yielding a mature enzyme of 274 amino acids.
- LepB shares 72% sequence identity with LepA, conserving key catalytic residues.
- Purified LepB exhibits lower enzymatic activity and reduced stability compared to LepA.
- Structural modeling suggests LepB adopts a similar tertiary structure to LepA, with functional differences attributed to specific amino acid variations.
Conclusions:
- LepB is identified as an isozyme of LepA, a lysine-specific endopeptidase.
- LepB possesses a tertiary structure highly similar to LepA, but with distinct biochemical properties.
- The findings provide insights into the functional diversity of lysyl endopeptidases within Lysobacter.