Micrococcal nuclease (EC 3.1.31.1, S7 Nuclease, 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 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.[1] The enzyme is also active against double-stranded DNA and RNA 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.[2] The enzyme is therefore easily inactivated by EGTA.
Sources
This enzyme is the extracellular nuclease of Staphylococcus aureus. Two strains, V8 and Foggi, yield almost identical enzymes.[3] A common source is E.coli cells carrying a cloned nuc gene encoding Staphylococcus 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, in 1969.[4] Higher-resolution, more recent crystal structures are available for the apo form[5] and for the thymidine-diphosphate-inhibited form.[6][7] As seen in the ribbon diagram above, the nuclease molecule has 3 long alpha helices and a 5-stranded, barrel-shaped beta sheet, in an arrangement known as the OB-fold (for oligonucleotide-binding fold) as classified in the SCOP database.
Applications
See also
References
- ^ Colin Dingwall, George P. Lomonossoff, Ronald A. Laskey, High sequence specificity of micrococcal nuclease, Nucleic Acids Research, Volume 9, Issue 12, 25 June 1981, Pages 2659–2674, https://doi.org/10.1093/nar/9.12.2659
- ^ Heins JN, Suriano JR, Taniuchi H, Anfinsen CB (1967). "Characterization of a nuclease produced by Staphylococcus aureus". J. Biol. Chem. 242 (5): 1016–20. doi:10.1016/S0021-9258(18)96225-3. PMID 6020427.
- ^ Cusumano CL, Taniuchi H, Anfinsen CB (1968). "Staphylococcal nuclease (Foggi strain). I. Order of cyanogen bromide fragments and a "fourth" histidine residue". J. Biol. Chem. 243 (18): 4769–77. doi:10.1016/S0021-9258(18)93185-6. PMID 5687719.
- ^ Arnone A, Bier J, et al. (1971). "A High Resolution Structure of an Inhibitor Complex of the Extracellular Nuclease of Staphylococcus aureus: I. Experimental Procedures and Chain Tracing". J. Biol. Chem. 246 (7): 2303–2316. doi:10.1016/S0021-9258(19)77221-4. PMID 5555571.
- ^ Truckses, D.M., Prehoda, K.E., Miller, S.C., Markley, J.L. and Somoza, J.R. (1996), Coupling between trans/cis proline isomerization and protein stability in staphylococcal nuclease. Protein Science, 5: 1907-1916. https://doi.org/10.1002/pro.5560050917 PDB: https://www.rcsb.org/structure/1SNO
- ^ Khangulov, V.S., Schlessman, J.L., Heroux, A., Garcia-Moreno, E.B. Crystal structure of Staphylococcal nuclease variant Delta+PHS V104E at cryogenic temperature PDB: https://www.rcsb.org/structure/3H6M
- ^ Loll, P.J. and Lattman, E.E. (1989), The crystal structure of the ternary complex of staphylococcal nuclease, Ca2+ and the inhibitor pdTp, refined at 1.65 Å. Proteins, 5: 183-201. https://doi.org/10.1002/prot.340050302 PDB: https://www.rcsb.org/structure/1SNC
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