{PDOC00865}
{PS01123; TNASE_1}
{PS01284; TNASE_2}
{PS50830; TNASE_3}
{BEGIN}
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* Thermonuclease domain signatures and profile *
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Staphylococcus aureus secretes a thermostable nuclease (EC 3.1.31.1), 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
    partition.
  - 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
    sempervirens.
  - 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
    function.
  - Caenorhabditis elegans F10g7.2 protein, which is similar to the human p100
    coactivator.

The TNase-like  domain  is  about  150  residues long and consists of a highly
twisted five  stranded  beta-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
beta-barrel often  capped  by  an  alpha-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.

-Consensus pattern: D-G-D-T-[LIVM]-x-[LIVMC]-x(9,10)-R-[LIVM]-x(2)-[LIVM]-D-x-
                    P-E
                    [R and E are active site residues]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for Corydalis sempervirens 38.1 Kd protein.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: [DT]-[KRP]-[YQ]-[GQ]-R-x-[LVY]-[GA]-x-[IV]-[FYW]
                    [R is an active site residue]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: April 2006 / Pattern revised.

[ 1] Hynes T.R., Fox R.O.
     "The crystal structure of staphylococcal nuclease refined at 1.7 A
     resolution."
     Proteins 10:92-105(1991).
     PubMed=1896431
[ 2] Chesneau O., el Solh N.
     "Primary structure and biological features of a thermostable nuclease
     isolated from Staphylococcus hyicus."
     Gene 145:41-47(1994).
     PubMed=8045422
[ 3] Ponting C.P.
     "P100, a transcriptional coactivator, is a human homologue of
     staphylococcal nuclease."
     Protein Sci. 6:459-463(1997).
     PubMed=9041650
[ 4] Callebaut I., Mornon J.-P.
     "The human EBNA-2 coactivator p100: multidomain organization and
     relationship to the staphylococcal nuclease fold and to the tudor
     protein involved in Drosophila melanogaster development."
     Biochem. J. 321:125-132(1997).
     PubMed=9003410

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{END}