PROSITE documentation PDOC00865
Thermonuclease domain signatures and profile


Staphylococcus aureus secretes a thermostable nuclease (EC, known as thermonuclease (TNase) or staphylococcal nuclease (SNase), which is a calcium-dependent enzyme that catalyzes the hydrolysis of both DNA and RNA at the 5' position of the phosphodiester bond yielding 3'-mononucleotides and dinucleotides [1]. Three residues, two arginines and a glutamate, have been implicated in the catalytic mechanism.

The sequence of the TNase of S.aureus is evolutionary related [2,3,4] to that of other Staphylococcus as well as to:

  - Nuclease from the pSa plasmid of Shigella flexneri.
  - Escherichia  coli  plasmid RP4 parB protein, which is involved in  plasmid
  - Escherichia coli plasmid R100 hypothetical protein (OrfA).
  - Rhizobium meliloti succinoglycan biosynthesis protein exoI.
  - Bacillus subtilis hypothetical protein yhcR.
  - Mycoplasma genitalium hypothetical lipoprotein MG186.
  - Haemophilus influenzae hypothetical protein HI1296.
  - Methanococcus jannaschii hypothetical protein MJ1439.
  - Yeast hypothetical protein Ygl085w.
  - A   38.1   Kd  protein  of  unknown  function  from  the  plant  Corydalis
  - Human  Epstein-Barr  virus  nuclear  antigen  2 (EBNA-2) coactivator p100,
    which contains  four repeats homologous to TNase. As each of these repeats
    lacks equivalent  TNase  catalytic  residues, they are unlikely to possess
    TNase-like activities,   but   may   mediate  single-stranded  DNA-binding
  - Caenorhabditis elegans F10g7.2 protein, which is similar to the human p100

The TNase-like domain is about 150 residues long and consists of a highly twisted five stranded β-barrel and three helices. It folds into two subdomains consisting of an oligonucleotide/oligosaccharide-binding (OB)-fold and two C-terminal helices. The OB-fold consists of a five-stranded Greek-key β-barrel often capped by an α-helix located between the third and fourth strands. It is found in several proteins that bind nucleic acid as well as carbohydrates, whereas others bind protein receptors or small molecules [4].

We developed two signature patterns based on conserved regions that each contain active site residues. We also developed a profile that spans the entire TNase-like domain.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

TNASE_3, PS50830; Thermonuclease domain profile  (MATRIX)

TNASE_1, PS01123; Thermonuclease family signature 1  (PATTERN)

TNASE_2, PS01284; Thermonuclease family signature 2  (PATTERN)


1AuthorsHynes T.R. Fox R.O.
TitleThe crystal structure of staphylococcal nuclease refined at 1.7 A resolution.
SourceProteins 10:92-105(1991).
PubMed ID1896431

2AuthorsChesneau O. el Solh N.
TitlePrimary structure and biological features of a thermostable nuclease isolated from Staphylococcus hyicus.
SourceGene 145:41-47(1994).
PubMed ID8045422

3AuthorsPonting C.P.
TitleP100, a transcriptional coactivator, is a human homologue of staphylococcal nuclease.
SourceProtein Sci. 6:459-463(1997).
PubMed ID9041650

4AuthorsCallebaut I. Mornon J.-P.
TitleThe human EBNA-2 coactivator p100: multidomain organization and relationship to the staphylococcal nuclease fold and to the tudor protein involved in Drosophila melanogaster development.
SourceBiochem. J. 321:125-132(1997).
PubMed ID9003410

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