ID   PGLX_ECOHS              Reviewed;        1205 AA.
AC   P0DUF9; A0A7M3S2P4;
DT   02-JUN-2021, integrated into UniProtKB/Swiss-Prot.
DT   02-JUN-2021, sequence version 1.
DT   03-AUG-2022, entry version 5.
DE   RecName: Full=Adenine-specific methyltransferase BrxX {ECO:0000303|PubMed:30418590};
DE            EC=2.1.1.72 {ECO:0000269|PubMed:30418590};
DE   AltName: Full=BREX protein PglX {ECO:0000305};
GN   Name=pglX; Synonyms=brxX {ECO:0000303|PubMed:30418590};
GN   OrderedLocusNames=EcHS_A0339;
OS   Escherichia coli O9:H4 (strain HS).
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Escherichia.
OX   NCBI_TaxID=331112;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=HS;
RX   PubMed=18676672; DOI=10.1128/jb.00619-08;
RA   Rasko D.A., Rosovitz M.J., Myers G.S.A., Mongodin E.F., Fricke W.F.,
RA   Gajer P., Crabtree J., Sebaihia M., Thomson N.R., Chaudhuri R.,
RA   Henderson I.R., Sperandio V., Ravel J.;
RT   "The pangenome structure of Escherichia coli: comparative genomic analysis
RT   of E. coli commensal and pathogenic isolates.";
RL   J. Bacteriol. 190:6881-6893(2008).
RN   [2]
RP   FUNCTION IN ANTIVIRAL DEFENSE, FUNCTION AS A DNA METHYLASE, INDUCTION, AND
RP   DISRUPTION PHENOTYPE.
RC   STRAIN=HS;
RX   PubMed=30418590; DOI=10.1093/nar/gky1125;
RA   Gordeeva J., Morozova N., Sierro N., Isaev A., Sinkunas T., Tsvetkova K.,
RA   Matlashov M., Truncaite L., Morgan R.D., Ivanov N.V., Siksnys V., Zeng L.,
RA   Severinov K.;
RT   "BREX system of Escherichia coli distinguishes self from non-self by
RT   methylation of a specific DNA site.";
RL   Nucleic Acids Res. 47:253-265(2019).
RN   [3]
RP   FUNCTION IN ANTIVIRAL DEFENSE, ACTIVITY REGULATION, SUBUNIT, AND
RP   INTERACTION WITH PHAGE T7 OCR.
RC   STRAIN=HS;
RX   PubMed=32515786; DOI=10.1093/nar/gkaa510;
RA   Isaev A., Drobiazko A., Sierro N., Gordeeva J., Yosef I., Qimron U.,
RA   Ivanov N.V., Severinov K.;
RT   "Phage T7 DNA mimic protein Ocr is a potent inhibitor of BREX defence.";
RL   Nucleic Acids Res. 48:7601-7602(2020).
CC   -!- FUNCTION: BREX systems (bacteriophage exclusion) provide immunity
CC       against bacteriophage. Part of a type 1 BREX system which protects
CC       against dsDNA phage. This system allows phage adsorption but prevents
CC       phage DNA replication, without degradation of the phage DNA.
CC       Methylation of bacterial DNA by this protein guides self/non-self
CC       discrimination. When the brxA-brxB-brxC-pglX-pglZ-brxL genes are
CC       transformed into a susceptible E.coli strain (BW25113) they confer very
CC       high resistance to infection by bacteriophage VR7 and VpaE1, about 100-
CC       fold protection against lambda, T5 and T7 (probably with a mutated 0.3
CC       gene) and no protection against RNA phage Qbeta, ssDNA phage M13 or
CC       dSDNA phage T4 and VR5. Glycosylated phage DNA is not susceptible to
CC       BREX. The BREX system does not confer resistance to lysogenic lambda
CC       phage, i.e. prophage that are integrated into the chromosomal DNA and
CC       then induced to form phage. {ECO:0000269|PubMed:30418590,
CC       ECO:0000269|PubMed:32515786}.
CC   -!- FUNCTION: Methylates the adenine in the fifth position of the hexamer
CC       5'-GGTAAG-3' in genomic DNA; methylates the same sequence in the few
CC       phage that escape the BREX system. Methylated phage are now resistant
CC       to BREX, showing immunity is provided by an epigenetic modification.
CC       Expression of this protein alone has no effect on phage infection, does
CC       not lead to methylated DNA and mildly inhibits growth.
CC       {ECO:0000269|PubMed:30418590}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an
CC         N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-
CC         homocysteine; Xref=Rhea:RHEA:15197, Rhea:RHEA-COMP:12418, Rhea:RHEA-
CC         COMP:12419, ChEBI:CHEBI:15378, ChEBI:CHEBI:57856, ChEBI:CHEBI:59789,
CC         ChEBI:CHEBI:90615, ChEBI:CHEBI:90616; EC=2.1.1.72;
CC         Evidence={ECO:0000269|PubMed:30418590};
CC   -!- ACTIVITY REGULATION: Methyltransferase activity is partially inhibited
CC       (20% reduction) by phage T7 protein OCR (AC P03775, gene 0.3).
CC       Viability of cells overexpressing OCR is unaffected.
CC       {ECO:0000269|PubMed:32515786}.
CC   -!- SUBUNIT: Interacts with phage T7 protein Ocr (AC P03775, gene 0.3)
CC       during an infection and when the protein is expressed from a plasmid.
CC       {ECO:0000269|PubMed:32515786}.
CC   -!- INDUCTION: Transcribed at slowly increasing levels as cells progress
CC       from lag to exponential to stationary phase.
CC       {ECO:0000269|PubMed:30418590}.
CC   -!- DISRUPTION PHENOTYPE: No methylation of 5'-GGTAAG-3' in chromosomal
CC       DNA, BREX no longer confers phage resistance.
CC       {ECO:0000269|PubMed:30418590}.
CC   -!- SIMILARITY: Belongs to the methyltransferase superfamily. PglX adenine
CC       methyltransferase family. {ECO:0000305}.
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DR   EMBL; CP000802; ABV04727.1; -; Genomic_DNA.
DR   RefSeq; WP_001095585.1; NC_009800.1.
DR   AlphaFoldDB; P0DUF9; -.
DR   KEGG; ecx:EcHS_A0339; -.
DR   OMA; RIIAIRF; -.
DR   Proteomes; UP000001123; Chromosome.
DR   GO; GO:0003677; F:DNA binding; IEA:InterPro.
DR   GO; GO:0008170; F:N-methyltransferase activity; IEA:InterPro.
DR   GO; GO:0009007; F:site-specific DNA-methyltransferase (adenine-specific) activity; IEA:UniProtKB-EC.
DR   GO; GO:0051607; P:defense response to virus; IEA:UniProtKB-KW.
DR   Gene3D; 3.40.50.150; -; 1.
DR   InterPro; IPR003356; DNA_methylase_A-5.
DR   InterPro; IPR002052; DNA_methylase_N6_adenine_CS.
DR   InterPro; IPR029063; SAM-dependent_MTases_sf.
DR   Pfam; PF02384; N6_Mtase; 1.
DR   SUPFAM; SSF53335; SSF53335; 1.
DR   PROSITE; PS00092; N6_MTASE; 1.
DR   PROSITE; PS00589; PTS_HPR_SER; 1.
PE   1: Evidence at protein level;
KW   Antiviral defense; Methyltransferase; S-adenosyl-L-methionine; Transferase.
FT   CHAIN           1..1205
FT                   /note="Adenine-specific methyltransferase BrxX"
FT                   /id="PRO_0000452163"
SQ   SEQUENCE   1205 AA;  137965 MW;  22E426D20634029C CRC64;
     MNTNNIKKYA PQARNDFRDA VIQKLTTLGI AADKKGNLQI AEAETIGETV RYGQFDYPLS
     TLPRRERLVK RAREQGFEVL VEHCAYTWFN RLCAIRYMEL HGYLDHGFRM LSHPETPTAF
     EVLDHVPEVA EALLPESKAQ LVEMKLSGNQ DEALYRELLL GQCHALHHAM PFLFEAVDDE
     AELLLPDNLT RTDSILRGLV DDIPEEDWEQ VEVIGWLYQF YISEKKDAVI GKVVKSEDIP
     AATQLFTPNW IVQYLVQNSV GRQWLQTYPD SPLKDKMEYY IEPAEQTPEV QAQLAAITPA
     SIEPESIKVL DPACGSGHIL TEAYNVLKAI YEERGYRTRD IPQLILENNI FGLDIDDRAA
     QLSGFAMLML ARQDDRRILG RGVRLNIVSL QESKLDIAEV WTKLNFHQHM QRGSMGDMFT
     QGTALANTDS AEYKLLMRTL ALFTSAKTLG SLIQVPQEDE AALKAFLERL YRLAVEGDIQ
     QKEAAAELIP YIQQAWILAQ RYDAVVANPP YMGGKGMNGD LKEFAKKQFP DSKSDLFAMF
     MQHAFSLLKE NGFNAQVNMQ SWMFLSSYEA LRGWLLDNKT FITMAHLGAR AFGQISGEVV
     QTTAWVIKNN HSGFYKPVFF RLVDDNEEHK KNNLLNRMNC FKNTLQNDFK KIPGSPIAYW
     ATLAFINSFL KLPALGTRAV KGLDTNGSID VFLRRWPEVS INSFDALGKG NSKWFPIAKG
     GELRKWFGNH EYIINYENDG IELRKNKANL RNKDMYFQEG GTWTVVSTTG FSMRYMPKGF
     LFDQGGSAVF CENNDELSIY NILACMNSKY INYSASLICP TLNFTTGDVR KFPVIKNNHL
     EDLAKKAIEI SKADWNQFET SWEFSKNKLI EHKGNVAYSY ASYCNFQDKL YEQLVNIEKN
     INNIIEEILG FKIETTENSE LITLNSNKIY RYGQSETNDT FLNRHRSDTI SELISYSVGC
     QMGRYSLDRE GLVYAHEGNK GFAELAAEGA YKTFPADNDG ILPLMDDEWF EDDVTSRVKE
     FVRTVWGEEH LQENLEFIAE SLCLYAIKPK KGESALETIR RYLSTQFWKD HMKMYKKRPI
     YWLFSSGKEK AFECLVYLHR YNDATLSRMR TEYVVPLLAR YQANIDRLND QLDEASGGEA
     TRLKRERDSL IKKFSELRSY DDRLRHYADM RISIDLDDGV KVNYGKFGDL LADVKAITGN
     APEAI