ID   T1SP_ECOLX              Reviewed;         401 AA.
AC   P17222;
DT   01-AUG-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1990, sequence version 1.
DT   25-MAY-2022, entry version 61.
DE   RecName: Full=Type I restriction enzyme EcoprrI specificity subunit {ECO:0000305};
DE            Short=S protein;
DE   AltName: Full=Type I specificity subunit S.EcoprrI {ECO:0000303|PubMed:12654995};
DE            Short=S.EcoprrI {ECO:0000303|PubMed:12654995};
DE   AltName: Full=Type-1 restriction enzyme EcoprrI specificity subunit;
GN   Name=prrB; Synonyms=orfB {ECO:0000303|PubMed:1691706};
OS   Escherichia coli.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Escherichia.
OX   NCBI_TaxID=562;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=CTR5X;
RX   PubMed=1691706; DOI=10.1002/j.1460-2075.1990.tb08253.x;
RA   Levitz R., Chapman D., Amitsur M., Green R., Snyder L., Kaufmann G.;
RT   "The optional E. coli prr locus encodes a latent form of phage T4-induced
RT   anticodon nuclease.";
RL   EMBO J. 9:1383-1389(1990).
RN   [2]
RP   NOMENCLATURE.
RX   PubMed=12654995; DOI=10.1093/nar/gkg274;
RA   Roberts R.J., Belfort M., Bestor T., Bhagwat A.S., Bickle T.A.,
RA   Bitinaite J., Blumenthal R.M., Degtyarev S.K., Dryden D.T., Dybvig K.,
RA   Firman K., Gromova E.S., Gumport R.I., Halford S.E., Hattman S.,
RA   Heitman J., Hornby D.P., Janulaitis A., Jeltsch A., Josephsen J., Kiss A.,
RA   Klaenhammer T.R., Kobayashi I., Kong H., Krueger D.H., Lacks S.,
RA   Marinus M.G., Miyahara M., Morgan R.D., Murray N.E., Nagaraja V.,
RA   Piekarowicz A., Pingoud A., Raleigh E., Rao D.N., Reich N., Repin V.E.,
RA   Selker E.U., Shaw P.C., Stein D.C., Stoddard B.L., Szybalski W.,
RA   Trautner T.A., Van Etten J.L., Vitor J.M., Wilson G.G., Xu S.Y.;
RT   "A nomenclature for restriction enzymes, DNA methyltransferases, homing
RT   endonucleases and their genes.";
RL   Nucleic Acids Res. 31:1805-1812(2003).
CC   -!- FUNCTION: The specificity (S) subunit of a type I restriction enzyme;
CC       this subunit dictates DNA sequence specificity. The M and S subunits
CC       together form a methyltransferase (MTase) that methylates two adenine
CC       residues of the sequence 5'-CCAN(7)ATGC-3'. In the presence of the R
CC       subunit the complex can also act as an endonuclease, binding to the
CC       same target sequence but cutting the DNA some distance from this site.
CC       Whether the DNA is cut or modified depends on the methylation state of
CC       the target sequence. When the target site is unmodified, the DNA is
CC       cut. When the target site is hemimethylated, the complex acts as a
CC       maintenance MTase modifying the DNA so that both strands become
CC       methylated. After locating a non-methylated recognition site, the
CC       enzyme complex serves as a molecular motor that translocates DNA in an
CC       ATP-dependent manner until a collision occurs that triggers cleavage.
CC       {ECO:0000250|UniProtKB:P05719, ECO:0000303|PubMed:12654995}.
CC   -!- SUBUNIT: The type I restriction/modification system is composed of
CC       three polypeptides R, M and S; the restriction enzyme has stoichiometry
CC       R(2)M(2)S(1) while the methyltransferase is M(2)S(1).
CC       {ECO:0000250|UniProtKB:P05719}.
CC   -!- DOMAIN: Contains two DNA recognition domains, each specifying
CC       recognition of one of the two defined components of the target
CC       sequence. {ECO:0000250|UniProtKB:P05719}.
CC   -!- MISCELLANEOUS: Type I restriction and modification enzymes are complex,
CC       multifunctional systems which require ATP, S-adenosyl methionine and
CC       Mg(2+) as cofactors and, in addition to their endonucleolytic and
CC       methylase activities, are potent DNA-dependent ATPases.
CC       {ECO:0000250|UniProtKB:P05719}.
CC   -!- SIMILARITY: Belongs to the type-I restriction system S methylase
CC       family. {ECO:0000305}.
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DR   EMBL; X52284; CAA36526.1; -; Genomic_DNA.
DR   PIR; S09626; S09626.
DR   AlphaFoldDB; P17222; -.
DR   SMR; P17222; -.
DR   REBASE; 3733; S.EcoprrI.
DR   PRO; PR:P17222; -.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0009307; P:DNA restriction-modification system; IEA:UniProtKB-KW.
DR   Gene3D; 3.90.220.20; -; 2.
DR   InterPro; IPR000055; Restrct_endonuc_typeI_TRD.
DR   InterPro; IPR044946; Restrct_endonuc_typeI_TRD_sf.
DR   Pfam; PF01420; Methylase_S; 2.
PE   3: Inferred from homology;
KW   DNA-binding; Restriction system.
FT   CHAIN           1..401
FT                   /note="Type I restriction enzyme EcoprrI specificity
FT                   subunit"
FT                   /id="PRO_0000198037"
SQ   SEQUENCE   401 AA;  45451 MW;  4CA12A99158991ED CRC64;
     MSELSYLEKL MDGVEVEWLP LSKVFNLRNG YTPSKTKKEF WANGDIPWFR MDDIRENGRI
     LGSSLQKISS CAVKGGKLFP ENSILISTSA TIGEHALITV PHLANQRFTC LALKESYADC
     FDIKFLFYYC FSLAEWCRKN TTMSSFASVD MDGFKKFLIP RPCPDNPEKS LAIQSEIVRI
     LDKFSALTAE LTAELTAELS MRKKQYNYYR DQLLSFKEDE VEGKRKTLGE IMKMRAGQHI
     SAHNIIERKE ESYIYPCFGG NGIRGYVKEK SHDGEHLLIG RQGALCGNVQ RMKGQFYATE
     HAVVVSVMPG INIDWAFHML TAMNLNQYAS KSAQPGLAVG KLQELKLFVP SIERQIYIAA
     ILDKFDTLTN SITEVSRVKS SCARNSTNII EICYLVSRSR K