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A serine/threonine protein kinase from Mycobacterium tuberculosis
P Peirs1, L De Wit, M Braibant
1Departement of Virology, Institut Pasteur, Brussels, Belgium.
European Journal of Biochemistry
|March 1, 1997
Summary
Researchers identified a novel serine/threonine protein kinase, Mbk (mycobacterial protein kinase), in Mycobacterium tuberculosis. This kinase exhibits autophosphorylation and phosphorylates substrates, representing the first characterized kinase of its kind in Mycobacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Mycobacterium tuberculosis harbors numerous uncharacterized genes.
- Protein kinases play crucial roles in cellular signaling and regulation.
Purpose of the Study:
- To identify and characterize novel protein kinases in Mycobacterium tuberculosis.
- To investigate the enzymatic activity and structural features of the identified kinase.
Main Methods:
- Genomic DNA sequencing and gene cloning.
- In vitro coupled transcription/translation for size confirmation.
- Overexpression in E. coli and purification of recombinant protein.
- Enzymatic assays for kinase activity (autophosphorylation and substrate phosphorylation).
- Southern blot and RT-PCR for gene detection and expression analysis in M. bovis BCG.
Main Results:
- A gene encoding a 70-kDa protein, named Mbk (mycobacterial protein kinase), was identified and sequenced.
- Mbk possesses N-terminal similarity to eukaryotic serine/threonine protein kinases and features transmembrane segments.
- Recombinant Mbk demonstrated autophosphorylation on threonine and phosphorylation of myelin basic protein and histones on serine residues in a manganese-dependent manner.
- Mbk activity was inhibited by calcium and staurosporine.
- A homologous gene was detected in M. bovis BCG, with its expression confirmed.
Conclusions:
- Mbk is the first characterized serine/threonine protein kinase in Mycobacteria.
- The kinase exhibits structural and functional similarities to eukaryotic counterparts.
- Its biological role remains to be elucidated, but it represents a potential target for further research.