Restriction enzymes: Sau3AI

Restriction enzymes, also known as endonucleases, are a type of proteins that cleave the phosphodiester bonds of DNA chains at or near a specific recognition site (the sequence of nucleotides is located by the enzyme itself). These enzymes can be isolated from the bacterial cells that produce them and then used to manipulate fragments of DNA (that may contain genes). For this reason, restriction enzymes are indispensable tools for recombinant DNA technology and genetic engeneering. Their applications include molecular cloning, genotyping, RFLP, SNP, etc.

Sau3AI is an example of a type II restriction enzyme, cutting DNA close or within the nucleotide sequence. In this case, the nucleotide sequence recognized by the enzyme is _5’GATC_3’ , cleaving the DNA chain before the G (guanine) nucleotide. Its optimal reaction temperature is 37ºC and it should be stored at -20ºC to prevent its activity.

                                 Figure 1- Crystal structure of the C-terminal of Sau3AI fragment.

References:

• Thermo Fisher Scientific. (2016). Bsp143I (Sau3AI) (10 U/µL). Consulted on november 16th 2018: https://www.thermofisher.com/order/catalog/product/ER0781

• National Center for Biotechnology Information. (2014). 4PXG: Crystal Structure Of Typeii Restriction Enzyme Sau3ai. Consulted on november 16th 2018: https://www.ncbi.nlm.nih.gov/Structure/pdb/4PXG

• ENCYCLOPÆDIA BRITANNICA. (2018). Restriction enzyme. Consulted on november 16th 2018: https://www.britannica.com/science/restriction-enzyme

• New England Biolabs. Sau3AI. Consulted on november 16th 2018: https://www.neb.com/products/r0169-sau3ai#Product%20Information