The restriction endonucleases in Bacillus amyloliquefaciens N strain. Substrate specificities

Area of Science:

• Molecular Biology
• Enzymology
• Genetics

Background:

• Restriction endonucleases are enzymes that cleave DNA at specific recognition sites.
• Bacillus amyloliquefaciens is a source of valuable restriction enzymes used in molecular biology.
• Understanding the properties and specificities of novel restriction enzymes is crucial for genetic engineering and DNA analysis.

Purpose of the Study:

• To isolate and characterize novel restriction endonucleases from Bacillus amyloliquefaciens N strain.
• To compare the enzymatic activities and substrate specificities of the isolated endonucleases.
• To investigate the potential applications of these enzymes in DNA manipulation.

Main Methods:

• Cell-free extracts of Bacillus amyloliquefaciens N strain were prepared.
• Gel filtration and DEAE-cellulose chromatography were employed for enzyme purification.
• Enzyme activity was assessed using various DNA substrates, including phage lambda DNA, Bacillus phage phi 105C DNA, and others.

Main Results:

• Two restriction endonucleases, R.BamNI (lower molecular weight) and R.BamNx (higher molecular weight), were successfully isolated.
• Both enzymes required Mg2+ for activity.
• R.BamNx demonstrated broader DNA cleavage activity compared to R.BamNI, cleaving Bacillus phage phi 105C DNA at both modified and unmodified sites, as well as DNA from E. coli phage T7, lambdadvl, SV40, and ColEI, but not Bacillus phages phi 29 and M2.

Conclusions:

• Bacillus amyloliquefaciens N strain harbors at least two distinct restriction endonucleases with different molecular weights and substrate specificities.
• R.BamNx is a versatile enzyme with potential applications in diverse DNA analysis and manipulation techniques.
• The differential cleavage of modified and unmodified sites on Bacillus phage phi 105C DNA by R.BamNx provides insights into DNA modification systems.