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Agmenellum quadruplicatum M.AquI, a novel modification methylase
1Sylvius Laboratories, Department of Medical Biochemistry, University of Leiden, The Netherlands.
Journal of Bacteriology
|January 1, 1990
Summary
The Agmenellum quadruplicatum type II modification methylase gene was cloned and expressed in E. coli. Both predicted peptides from overlapping open reading frames are essential for full methylase activity.
Area of Science:
- Molecular Biology
- Enzymology
- Genetics
Background:
- Type II modification methylases are crucial enzymes in DNA restriction-modification systems.
- Understanding these enzymes provides insights into DNA methylation and bacterial defense mechanisms.
Purpose of the Study:
- To clone and characterize the type II modification methylase gene from Agmenellum quadruplicatum.
- To investigate the genetic organization and functional requirements of the methylase.
Main Methods:
- Cloning of the Agmenellum quadruplicatum methylase gene into Escherichia coli using R.Sau3A restriction fragments.
- Analysis of the coding sequence, including identification of open reading frames (ORFs).
- In vivo complementation experiments to assess methylase activity.
Main Results:
- A 4.5 kilobase fragment containing the methylase gene was successfully cloned in E. coli.
- The coding sequence spans 1,156 base pairs with two parallel, partly overlapping ORFs (248 and 139 codons).
- Both predicted peptides are necessary for complete methylase function.
Conclusions:
- The type II modification methylase of Agmenellum quadruplicatum requires the expression of two distinct peptides for activity.
- The deduced amino acid sequences show similarity to other deoxycytidylate methylases, suggesting conserved functional domains.