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Recombinant cyclophilins lack nuclease activity
1Universidad de Oviedo, Departamento de Biología Funcional, Area de Microbiologia, Julian Claveria s/n, Oviedo 33006, Spain.
Journal of Bacteriology
|September 3, 2004
Summary
Human and bacterial cyclophilins were thought to degrade DNA. However, this study reveals their supposed nuclease activity is actually due to contamination, not an intrinsic protein property.
Area of Science:
- Molecular Biology
- Biochemistry
Background:
- Single-domain cyclophilins from prokaryotes and eukaryotes have been implicated as nucleases.
- Their proposed role involves DNA degradation during bacterial cell death and eukaryotic apoptosis.
Purpose of the Study:
- To investigate the nuclease activity of human and bacterial cyclophilins.
- To determine if the observed DNA degradation is an intrinsic property of cyclophilins or due to other factors.
Main Methods:
- Purification of recombinant human and bacterial cyclophilins.
- Assays to detect nuclease activity.
- Analysis of protein contamination using host cell components.
Main Results:
- Recombinant cyclophilins did not exhibit intrinsic nuclease activity.
- The apparent nuclease activity was attributed to contamination by Escherichia coli endonuclease.
- This contamination was present in both human and bacterial cyclophilin preparations.
Conclusions:
- The nuclease activity previously attributed to cyclophilins is not an intrinsic property of these proteins.
- Contamination with host cell endonucleases is the likely source of the observed DNA degradation.
- Re-evaluation of cyclophilin function regarding DNA degradation is warranted.