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Endogenous ADP-ribosylation of proteins in Mycobacterium smegmatis
1Department of Bacteriology, University of Wisconsin--Madison, 53706, USA.
Abstract:
Endogenous ADP-ribosylation of two proteins with molecular weights of 30,000 (30K) and 80,000 (80K) was detected in cell extracts of Mycobacterium smegmatis. Modification of these proteins was enzymatic. The ADP-ribose bound to 30K was removed by HgCl2 but not by NH2OH, suggesting the modification of a cysteine residue. The ADP-ribose bound to 80K was not removed by either HgCl2 or NH2OH, which is consistent with the modification of an asparagine residue. ADP-ribosylation of 80K appeared to be reversible.
Insights
Mycobacterium smegmatis modifies proteins via ADP-ribosylation. This enzymatic process targets 30K and 80K proteins, with distinct modification sites suggesting cysteine and asparagine residues, respectively.
Area of Science:
- Molecular Biology
- Biochemistry
- Microbiology
Background:
- ADP-ribosylation is a post-translational modification involved in various cellular processes.
- Understanding protein modification in Mycobacterium smegmatis is crucial for deciphering bacterial physiology.
Purpose of the Study:
- To investigate endogenous ADP-ribosylation in Mycobacterium smegmatis.
- To identify the specific proteins modified and the nature of these modifications.
Main Methods:
- Analysis of cell extracts from Mycobacterium smegmatis.
- Enzymatic assays to confirm ADP-ribosylation.
- Chemical treatments (HgCl2, NH2OH) to characterize the modification sites.
Main Results:
- Endogenous ADP-ribosylation was detected on two proteins, 30K and 80K.
- The ADP-ribose on the 30K protein was removed by HgCl2, indicating cysteine residue modification.
- The ADP-ribose on the 80K protein was resistant to HgCl2 and NH2OH, consistent with asparagine residue modification.
- ADP-ribosylation of the 80K protein appeared to be reversible.
Conclusions:
- Mycobacterium smegmatis exhibits endogenous ADP-ribosylation of specific proteins.
- The study identified distinct modification sites, suggesting cysteine and asparagine residues are involved.
- The reversible nature of 80K protein modification warrants further investigation.