ID   XNI_SHIBS               Reviewed;         251 AA.
AC   Q31XJ2;
DT   21-AUG-2007, integrated into UniProtKB/Swiss-Prot.
DT   24-NOV-2009, sequence version 2.
DT   03-AUG-2022, entry version 85.
DE   RecName: Full=Flap endonuclease Xni {ECO:0000255|HAMAP-Rule:MF_01192};
DE            Short=FEN {ECO:0000255|HAMAP-Rule:MF_01192};
DE            EC=3.1.-.- {ECO:0000255|HAMAP-Rule:MF_01192};
GN   Name=xni {ECO:0000255|HAMAP-Rule:MF_01192};
GN   Synonyms=ygdG {ECO:0000255|HAMAP-Rule:MF_01192};
GN   OrderedLocusNames=SBO_2679;
OS   Shigella boydii serotype 4 (strain Sb227).
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Shigella.
OX   NCBI_TaxID=300268;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=Sb227;
RX   PubMed=16275786; DOI=10.1093/nar/gki954;
RA   Yang F., Yang J., Zhang X., Chen L., Jiang Y., Yan Y., Tang X., Wang J.,
RA   Xiong Z., Dong J., Xue Y., Zhu Y., Xu X., Sun L., Chen S., Nie H., Peng J.,
RA   Xu J., Wang Y., Yuan Z., Wen Y., Yao Z., Shen Y., Qiang B., Hou Y., Yu J.,
RA   Jin Q.;
RT   "Genome dynamics and diversity of Shigella species, the etiologic agents of
RT   bacillary dysentery.";
RL   Nucleic Acids Res. 33:6445-6458(2005).
CC   -!- FUNCTION: Has flap endonuclease activity. During DNA replication, flap
CC       endonucleases cleave the 5'-overhanging flap structure that is
CC       generated by displacement synthesis when DNA polymerase encounters the
CC       5'-end of a downstream Okazaki fragment. {ECO:0000255|HAMAP-
CC       Rule:MF_01192}.
CC   -!- COFACTOR:
CC       Name=Mg(2+); Xref=ChEBI:CHEBI:18420;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01192};
CC       Note=Binds 2 Mg(2+) per subunit. Only one magnesium ion has a direct
CC       interaction with the protein, the other interactions are indirect.
CC       {ECO:0000255|HAMAP-Rule:MF_01192};
CC   -!- COFACTOR:
CC       Name=K(+); Xref=ChEBI:CHEBI:29103;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01192};
CC       Note=Binds 1 K(+) per subunit. The potassium ion strongly increases the
CC       affinity for DNA. {ECO:0000255|HAMAP-Rule:MF_01192};
CC   -!- SIMILARITY: Belongs to the Xni family. {ECO:0000255|HAMAP-
CC       Rule:MF_01192}.
CC   -!- SEQUENCE CAUTION:
CC       Sequence=ABB67216.1; Type=Erroneous initiation; Note=Extended N-terminus.; Evidence={ECO:0000305};
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DR   EMBL; CP000036; ABB67216.1; ALT_INIT; Genomic_DNA.
DR   RefSeq; WP_000268232.1; NC_007613.1.
DR   AlphaFoldDB; Q31XJ2; -.
DR   SMR; Q31XJ2; -.
DR   EnsemblBacteria; ABB67216; ABB67216; SBO_2679.
DR   KEGG; sbo:SBO_2679; -.
DR   HOGENOM; CLU_004675_1_2_6; -.
DR   Proteomes; UP000007067; Chromosome.
DR   GO; GO:0017108; F:5'-flap endonuclease activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0000287; F:magnesium ion binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0030955; F:potassium ion binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0033567; P:DNA replication, Okazaki fragment processing; IEA:UniProtKB-UniRule.
DR   CDD; cd09898; H3TH_53EXO; 1.
DR   HAMAP; MF_01192; Xni; 1.
DR   InterPro; IPR020046; 5-3_exonucl_a-hlix_arch_N.
DR   InterPro; IPR002421; 5-3_exonuclease.
DR   InterPro; IPR036279; 5-3_exonuclease_C_sf.
DR   InterPro; IPR020045; DNA_polI_H3TH.
DR   InterPro; IPR038969; FEN.
DR   InterPro; IPR008918; HhH2.
DR   InterPro; IPR029060; PIN-like_dom_sf.
DR   InterPro; IPR022895; Xni.
DR   PANTHER; PTHR42646; PTHR42646; 1.
DR   Pfam; PF01367; 5_3_exonuc; 1.
DR   Pfam; PF02739; 5_3_exonuc_N; 1.
DR   SMART; SM00475; 53EXOc; 1.
DR   SMART; SM00279; HhH2; 1.
DR   SUPFAM; SSF47807; SSF47807; 1.
DR   SUPFAM; SSF88723; SSF88723; 1.
PE   3: Inferred from homology;
KW   DNA-binding; Endonuclease; Hydrolase; Magnesium; Metal-binding; Nuclease;
KW   Potassium.
FT   CHAIN           1..251
FT                   /note="Flap endonuclease Xni"
FT                   /id="PRO_0000297882"
FT   DOMAIN          160..249
FT                   /note="5'-3' exonuclease"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   REGION          184..189
FT                   /note="Interaction with DNA"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   BINDING         104
FT                   /ligand="Mg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:18420"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   BINDING         171
FT                   /ligand="K(+)"
FT                   /ligand_id="ChEBI:CHEBI:29103"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   BINDING         172
FT                   /ligand="K(+)"
FT                   /ligand_id="ChEBI:CHEBI:29103"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   BINDING         180
FT                   /ligand="K(+)"
FT                   /ligand_id="ChEBI:CHEBI:29103"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   BINDING         182
FT                   /ligand="K(+)"
FT                   /ligand_id="ChEBI:CHEBI:29103"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
FT   BINDING         185
FT                   /ligand="K(+)"
FT                   /ligand_id="ChEBI:CHEBI:29103"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01192"
SQ   SEQUENCE   251 AA;  28166 MW;  937A2CDCC58B03A5 CRC64;
     MAVHLLIVDA LNLIRRIHAV QGSPCVETCQ HALDQLIMHS QPTHAVAVFD DENRSSGWRH
     QRLPDYKAGR PPMPEELHDE MPALRAAFEQ RGVPCWSTSG NEADDLAATL AVKVTQAGHQ
     ATIVSTDKGY CQLLSPTLRI RDYFQKRWLD APFIDKEFGV QPQQLPDYWG LAGISSSKVP
     GVAGIGPKSA TQLLVEFQSL EGIYENLDAV AEKWRKKLET HKEMAFLCRD IARLQTDLHI
     DGNLQQLRLV R