S1 Nuclease Mapping

S1 Nuclease Mapping
Introduction
Properties of S1 Nuclease
S1 Mapping
DNA-mRNA Hybridization

1. S1 Nuclease Mapping Dr. Ema Sushan Minj Department of Microbiology

2. S1 Nuclease mapping - Gene expression is the process by which information encoded in a gene is used in the synthesis of a functional gene product known as protein. In case of RNA transcript - The removal of introns The exact locations of start and end points of transcription The signals that determine the start and end of transcription

3. Nuclease-S1 mapping is used to map the locations of the ends of RNA molecules and of any splice points within them in relation to specific sites (e.g., positions of restriction endonuclease cleavage) within the template DNA. The S1 nuclease is purified from Aspergillus oryzae . S1 Nuclease is an endonuclease that degrades ssDNA and RNA, but does not degrade dsDNA or RNA-DNA hybrids in native conformation.

4. Thus, its activity is similar to mung bean nuclease . The enzyme will also cleave a strand opposite to a nick on the complementary strand. The enzyme is used to remove overhang single-stranded termini from dsDNA , for selective cleavage of ssDNA and for mapping RNA transcripts. It is a laboratory method used to locate the 5’end of a transcript in a mixture of RNA using nuclease S1.

5. Properties of S1 nuclease At high ionic strength, low pH (4-4.5) and in the presence of Zn ions (cofactor), S1 nuclease digests ssDNA very efficiently. It is relatively stable against denaturing agents like urea, SDS and formaldehyde. It removes single stranded regions from dsDNA . (Conversion of cohesive ends to blunt ends) Cleaves hairpin loops generated during synthesis of DNA.

6. S1 mapping Technique developed by Berk and Sharp by the study of adenovirus mRNAs. This technique is used for quantifying the amount of mRNA transcript and it can therefore identify the level of transcription of the gene in the cell at a given time.

7. DNA-mRNA hybridization

8. Thank you