Micrococcal nuclease (, ''S7

Nuclease A nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously effect single and double stranded breaks in their ta ...

'', ''MNase'', ''spleen endonuclease'', ''thermonuclease'', ''nuclease T'', ''micrococcal endonuclease'', ''nuclease T, ''staphylococcal nuclease'', ''spleen phosphodiesterase'', ''Staphylococcus aureus nuclease'', ''Staphylococcus aureus nuclease B'', ''ribonucleate (deoxynucleate) 3'-nucleotidohydrolase'') is an endo-

exonuclease Exonucleases are enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain. A hydrolyzing reaction that breaks phosphodiester bonds at either the 3′ or the 5′ end occurs. Its close relative is the ...

that preferentially digests single-stranded nucleic acids. The rate of cleavage is 30 times greater at the 5' side of A or T than at G or C and results in the production of mononucleotides and oligonucleotides with terminal 3'- phosphates. The enzyme is also active against double-stranded DNA and

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

and all sequences will be ultimately cleaved.

Characteristics

The enzyme has a molecular weight of 16.9kDa. The pH optimum is reported as 9.2. The enzyme activity is strictly dependent on Ca²⁺ and the pH optimum varies according to Ca²⁺ concentration. The enzyme is therefore easily inactivated by EGTA.

Sources

This enzyme is the extracellular

nuclease A nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously effect single and double stranded breaks in their ta ...

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...

. Two strains, V8 and Foggi, yield almost identical enzymes. A common source is ''

E.coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Esche ...

'' cells carrying a cloned nuc gene encoding

Staphylococcus ''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. ''Staphylococcus'' species are facultative ...

aureus extracellular nuclease (micrococcal nuclease).

Structure

The 3-dimensional structure of micrococcal nuclease (then called Staphyloccal nuclease) was solved very early in the history of protein

crystallography Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The wor ...

, in 1969, deposited as now-obsolete Protein Data Bank file 1SNS. Higher-resolution, more recent crystal structures are available for the apo form as Protein Data Bank file 1SNO

and for the thymidine-diphosphate-inhibited form as Protein Data Bank file 3H6M

or 1SNC

As seen in the

ribbon diagram Ribbon diagrams, also known as Richardson diagrams, are three-dimensional space, 3D schematic representations of protein structure and are one of the most common methods of protein depiction used today. The ribbon shows the overall path and organ ...

above, the nuclease molecule has 3 long alpha helices and a 5-stranded, barrel-shaped

beta sheet The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a g ...

, in an arrangement known as the OB-fold (for oligonucleotide-binding fold) as classified in the SCOP database.

Applications

* CUT&RUN sequencing, antibody-targeted controlled cleavage by micrococcal nuclease for transcriptomic profiling. *Hydrolysis of nucleic acids in crude cell-free extracts. *Sequencing of

. *Preparation of rabbit reticulocyte lysates. *Studies of chromatin structure. *Removal of nucleic acids from laboratory protein preparations allowing for protein folding and structure-function studies. *Research on the mechanisms of protein folding.

References

*http://www.thermoscientificbio.com/dna-and-rna-modifying-enzymes/micrococcal-nuclease/ *http://www.worthington-biochem.com/NFCP/default.html *http://www.thermoscientificbio.com/uploadedFiles/Resources/en0181-usa-msds.pdf - A material and safety data sheet for the product *http://www.thermoscientificbio.com/uploadedFiles/Resources/en018-product-information.pdf - A Product Information sheet

External links

* * {{Portal bar, Biology, border=no

Proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

Molecular biology EC 3.1.31