ID   NSAD_SPHXE              Reviewed;         195 AA.
AC   Q9X9Q7;
DT   24-JUL-2013, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1999, sequence version 1.
DT   03-AUG-2022, entry version 72.
DE   RecName: Full=2-hydroxychromene-2-carboxylate isomerase;
DE            Short=HCCA isomerase;
DE            EC=5.99.1.4;
GN   Name=nsaD;
OS   Sphingobium xenophagum.
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Sphingomonadales;
OC   Sphingomonadaceae; Sphingobium.
OX   NCBI_TaxID=121428;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, AND ACTIVITY REGULATION.
RC   STRAIN=DSM 6383 / KCTC 2978 / NBRC 107872 / BN6;
RX   PubMed=16804169; DOI=10.1099/mic.0.28783-0;
RA   Keck A., Conradt D., Mahler A., Stolz A., Mattes R., Klein J.;
RT   "Identification and functional analysis of the genes for
RT   naphthalenesulfonate catabolism by Sphingomonas xenophaga BN6.";
RL   Microbiology 152:1929-1940(2006).
RN   [2]
RP   FUNCTION, CATALYTIC ACTIVITY, AND SUBSTRATE SPECIFICITY.
RC   STRAIN=DSM 6383 / KCTC 2978 / NBRC 107872 / BN6;
RX   DOI=10.1007/BF00695117;
RA   Kuhm A.E., Knackmuss H.-J., Stolz A.;
RT   "2-Hydroxychromene-2-carboxylate isomerase from bacteria that degrade
RT   naphthalenesulfonates.";
RL   Biodegradation 4:155-162(1993).
CC   -!- FUNCTION: Involved in the naphthalene and naphthalenesulfonate
CC       catabolic pathway. Catalyzes the reversible glutathione-dependent
CC       isomerization of 2-hydroxychromene-2-carboxylate (HCCA) to trans-O-
CC       hydroxybenzylidenepyruvate (THBPA). It can also use 2-
CC       hydroxybenzo[g]chromene-2-carboxylate as substrate.
CC       {ECO:0000269|PubMed:16804169, ECO:0000269|Ref.2}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2-hydroxychromene-2-carboxylate = (3E)-4-(2-hydroxyphenyl)-2-
CC         oxobut-3-enoate; Xref=Rhea:RHEA:27401, ChEBI:CHEBI:59350,
CC         ChEBI:CHEBI:59353; EC=5.99.1.4; Evidence={ECO:0000269|Ref.2};
CC   -!- COFACTOR:
CC       Name=glutathione; Xref=ChEBI:CHEBI:57925;
CC       Note=Glutathione seems to stabilize the enzyme, which loses activity
CC       rapidly in the absence of this compound.;
CC   -!- ACTIVITY REGULATION: Activated by salicylate.
CC       {ECO:0000269|PubMed:16804169}.
CC   -!- SIMILARITY: Belongs to the GST superfamily. NadH family. {ECO:0000305}.
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DR   EMBL; U65001; AAD45416.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q9X9Q7; -.
DR   SMR; Q9X9Q7; -.
DR   PRIDE; Q9X9Q7; -.
DR   KEGG; ag:AAD45416; -.
DR   BRENDA; 5.99.1.4; 10830.
DR   GO; GO:0018845; F:2-hydroxychromene-2-carboxylate isomerase activity; IDA:UniProtKB.
DR   GO; GO:0016491; F:oxidoreductase activity; IEA:InterPro.
DR   GO; GO:1901170; P:naphthalene catabolic process; IMP:UniProtKB.
DR   CDD; cd03022; DsbA_HCCA_Iso; 1.
DR   InterPro; IPR001853; DSBA-like_thioredoxin_dom.
DR   InterPro; IPR014440; HCCAis_GSTk.
DR   InterPro; IPR044087; NahD-like.
DR   InterPro; IPR036249; Thioredoxin-like_sf.
DR   Pfam; PF01323; DSBA; 1.
DR   PIRSF; PIRSF006386; HCCAis_GSTk; 1.
DR   SUPFAM; SSF52833; SSF52833; 1.
PE   1: Evidence at protein level;
KW   Aromatic hydrocarbons catabolism; Isomerase.
FT   CHAIN           1..195
FT                   /note="2-hydroxychromene-2-carboxylate isomerase"
FT                   /id="PRO_0000423056"
FT   ACT_SITE        13
FT                   /note="Nucleophile"
FT                   /evidence="ECO:0000250"
FT   BINDING         13
FT                   /ligand="glutathione"
FT                   /ligand_id="ChEBI:CHEBI:57925"
FT                   /evidence="ECO:0000250"
FT   BINDING         45
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         55..56
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         181..184
FT                   /ligand="glutathione"
FT                   /ligand_id="ChEBI:CHEBI:57925"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   195 AA;  22064 MW;  7E6FBAC96B3C6316 CRC64;
     MTKTIDFYFD FISPFSYLAQ VKLPDLARRT GCVIEYRPID IPEAKIAAGN YGPSNREVVP
     KIKVMMADLE RWAAKYEVPL TFPASFACSD WNCAALYARG QDQAEAFVTA AYHRIWGIGI
     DPRDQNELRG CAEDVGLDAD ALCEFVRSPA GQGEYRKART QAYQRGVFGA PMMFVDDQIF
     WGNDRLDFLE SYLLD