ID   LACB_STRMU              Reviewed;         171 AA.
AC   P26424;
DT   01-AUG-1992, integrated into UniProtKB/Swiss-Prot.
DT   28-NOV-2002, sequence version 2.
DT   25-MAY-2022, entry version 125.
DE   RecName: Full=Galactose-6-phosphate isomerase subunit LacB {ECO:0000255|HAMAP-Rule:MF_01556};
DE            EC=5.3.1.26 {ECO:0000255|HAMAP-Rule:MF_01556};
GN   Name=lacB {ECO:0000255|HAMAP-Rule:MF_01556}; OrderedLocusNames=SMU_1495;
OS   Streptococcus mutans serotype c (strain ATCC 700610 / UA159).
OC   Bacteria; Firmicutes; Bacilli; Lactobacillales; Streptococcaceae;
OC   Streptococcus.
OX   NCBI_TaxID=210007;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=1400164; DOI=10.1128/jb.174.19.6159-6170.1992;
RA   Rosey E.L., Stewart G.C.;
RT   "Nucleotide and deduced amino acid sequences of the lacR, lacABCD, and
RT   lacFE genes encoding the repressor, tagatose 6-phosphate gene cluster, and
RT   sugar-specific phosphotransferase system components of the lactose operon
RT   of Streptococcus mutans.";
RL   J. Bacteriol. 174:6159-6170(1992).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC 700610 / UA159;
RX   PubMed=12397186; DOI=10.1073/pnas.172501299;
RA   Ajdic D.J., McShan W.M., McLaughlin R.E., Savic G., Chang J., Carson M.B.,
RA   Primeaux C., Tian R., Kenton S., Jia H.G., Lin S.P., Qian Y., Li S.,
RA   Zhu H., Najar F.Z., Lai H., White J., Roe B.A., Ferretti J.J.;
RT   "Genome sequence of Streptococcus mutans UA159, a cariogenic dental
RT   pathogen.";
RL   Proc. Natl. Acad. Sci. U.S.A. 99:14434-14439(2002).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=aldehydo-D-galactose 6-phosphate = keto-D-tagatose 6-
CC         phosphate; Xref=Rhea:RHEA:13033, ChEBI:CHEBI:58255,
CC         ChEBI:CHEBI:134283; EC=5.3.1.26; Evidence={ECO:0000255|HAMAP-
CC         Rule:MF_01556};
CC   -!- PATHWAY: Carbohydrate metabolism; D-galactose 6-phosphate degradation;
CC       D-tagatose 6-phosphate from D-galactose 6-phosphate: step 1/1.
CC       {ECO:0000255|HAMAP-Rule:MF_01556}.
CC   -!- SUBUNIT: Heteromultimeric protein consisting of LacA and LacB.
CC       {ECO:0000255|HAMAP-Rule:MF_01556}.
CC   -!- SIMILARITY: Belongs to the LacAB/RpiB family. {ECO:0000255|HAMAP-
CC       Rule:MF_01556}.
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DR   EMBL; M80797; AAA26905.1; -; Genomic_DNA.
DR   EMBL; AE014133; AAN59149.1; -; Genomic_DNA.
DR   PIR; D43258; D43258.
DR   PIR; S27702; S27702.
DR   RefSeq; NP_721843.1; NC_004350.2.
DR   RefSeq; WP_002262464.1; NC_004350.2.
DR   AlphaFoldDB; P26424; -.
DR   SMR; P26424; -.
DR   STRING; 210007.SMU_1495; -.
DR   PRIDE; P26424; -.
DR   EnsemblBacteria; AAN59149; AAN59149; SMU_1495.
DR   GeneID; 66819105; -.
DR   KEGG; smu:SMU_1495; -.
DR   PATRIC; fig|210007.7.peg.1331; -.
DR   eggNOG; COG0698; Bacteria.
DR   HOGENOM; CLU_091396_2_0_9; -.
DR   OMA; ETHHANQ; -.
DR   PhylomeDB; P26424; -.
DR   UniPathway; UPA00702; UER00714.
DR   Proteomes; UP000002512; Chromosome.
DR   GO; GO:0050044; F:galactose-6-phosphate isomerase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0019388; P:galactose catabolic process; IEA:UniProtKB-UniPathway.
DR   GO; GO:0019512; P:lactose catabolic process via tagatose-6-phosphate; IEA:UniProtKB-UniRule.
DR   Gene3D; 3.40.1400.10; -; 1.
DR   HAMAP; MF_01556; LacB; 1.
DR   InterPro; IPR004784; LacB.
DR   InterPro; IPR003500; RpiB_LacA_LacB.
DR   InterPro; IPR036569; RpiB_LacA_LacB_sf.
DR   PANTHER; PTHR30345; PTHR30345; 1.
DR   Pfam; PF02502; LacAB_rpiB; 1.
DR   PIRSF; PIRSF005384; RpiB_LacA_B; 1.
DR   SUPFAM; SSF89623; SSF89623; 1.
DR   TIGRFAMs; TIGR01119; lacB; 1.
DR   TIGRFAMs; TIGR00689; rpiB_lacA_lacB; 1.
PE   3: Inferred from homology;
KW   Isomerase; Lactose metabolism; Reference proteome.
FT   CHAIN           1..171
FT                   /note="Galactose-6-phosphate isomerase subunit LacB"
FT                   /id="PRO_0000208150"
FT   CONFLICT        11
FT                   /note="V -> W (in Ref. 1; AAA26905)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        22
FT                   /note="L -> I (in Ref. 1; AAA26905)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   171 AA;  18950 MW;  61B99C48360506D6 CRC64;
     MKIAIGCDHI VTDVKMELSK HLKEEGYEVL DVGTYDFTRT HYPIFGKKVG EAVSSGEADL
     GVCMCGTGVG ISNAANKVPG VRTALVRDMT SALYSKEELN ANVVSFGGAI IGKLLLFDIV
     DAFIKAQYKP TEENKKLIAK IKHLEAHNDK QADPHFFDEF LEKWNRGDYH D