ID   RISB_CHLTB              Reviewed;         157 AA.
AC   B0BAI7;
DT   24-MAR-2009, integrated into UniProtKB/Swiss-Prot.
DT   26-FEB-2008, sequence version 1.
DT   10-JUN-2026, entry version 89.
DE   RecName: Full=6,7-dimethyl-8-ribityllumazine synthase {ECO:0000255|HAMAP-Rule:MF_00178};
DE            Short=DMRL synthase {ECO:0000255|HAMAP-Rule:MF_00178};
DE            Short=LS {ECO:0000255|HAMAP-Rule:MF_00178};
DE            Short=Lumazine synthase {ECO:0000255|HAMAP-Rule:MF_00178};
DE            EC=2.5.1.78 {ECO:0000255|HAMAP-Rule:MF_00178};
GN   Name=ribH {ECO:0000255|HAMAP-Rule:MF_00178};
GN   OrderedLocusNames=CTLon_0101;
OS   Chlamydia trachomatis serovar L2b (strain UCH-1/proctitis).
OC   Bacteria; Pseudomonadati; Chlamydiota; Chlamydiia; Chlamydiales;
OC   Chlamydiaceae; Chlamydia/Chlamydophila group; Chlamydia.
OX   NCBI_TaxID=471473;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=UCH-1/proctitis;
RX   PubMed=18032721; DOI=10.1101/gr.7020108;
RA   Thomson N.R., Holden M.T.G., Carder C., Lennard N., Lockey S.J., Marsh P.,
RA   Skipp P., O'Connor C.D., Goodhead I., Norbertzcak H., Harris B., Ormond D.,
RA   Rance R., Quail M.A., Parkhill J., Stephens R.S., Clarke I.N.;
RT   "Chlamydia trachomatis: genome sequence analysis of lymphogranuloma
RT   venereum isolates.";
RL   Genome Res. 18:161-171(2008).
CC   -!- FUNCTION: Catalyzes the formation of 6,7-dimethyl-8-ribityllumazine by
CC       condensation of 5-amino-6-(D-ribitylamino)uracil with 3,4-dihydroxy-2-
CC       butanone 4-phosphate. This is the penultimate step in the biosynthesis
CC       of riboflavin. {ECO:0000255|HAMAP-Rule:MF_00178}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=(2S)-2-hydroxy-3-oxobutyl phosphate + 5-amino-6-(D-
CC         ribitylamino)uracil = 6,7-dimethyl-8-(1-D-ribityl)lumazine +
CC         phosphate + 2 H2O + H(+); Xref=Rhea:RHEA:26152, ChEBI:CHEBI:15377,
CC         ChEBI:CHEBI:15378, ChEBI:CHEBI:15934, ChEBI:CHEBI:43474,
CC         ChEBI:CHEBI:58201, ChEBI:CHEBI:58830; EC=2.5.1.78;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_00178};
CC   -!- PATHWAY: Cofactor biosynthesis; riboflavin biosynthesis; riboflavin
CC       from 2-hydroxy-3-oxobutyl phosphate and 5-amino-6-(D-
CC       ribitylamino)uracil: step 1/2. {ECO:0000255|HAMAP-Rule:MF_00178}.
CC   -!- SIMILARITY: Belongs to the DMRL synthase family. {ECO:0000255|HAMAP-
CC       Rule:MF_00178}.
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DR   EMBL; AM884177; CAP06499.1; -; Genomic_DNA.
DR   RefSeq; WP_009872109.1; NC_010280.2.
DR   AlphaFoldDB; B0BAI7; -.
DR   SMR; B0BAI7; -.
DR   KEGG; ctl:CTLon_0101; -.
DR   HOGENOM; CLU_089358_1_1_0; -.
DR   UniPathway; UPA00275; UER00404.
DR   GO; GO:0005829; C:cytosol; IEA:TreeGrafter.
DR   GO; GO:0009349; C:riboflavin synthase complex; IEA:InterPro.
DR   GO; GO:0000906; F:6,7-dimethyl-8-ribityllumazine synthase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0009231; P:riboflavin biosynthetic process; IEA:UniProtKB-UniRule.
DR   CDD; cd09209; Lumazine_synthase-I; 1.
DR   Gene3D; 3.40.50.960; Lumazine/riboflavin synthase; 1.
DR   HAMAP; MF_00178; Lumazine_synth; 1.
DR   InterPro; IPR034964; LS.
DR   InterPro; IPR002180; LS/RS.
DR   InterPro; IPR036467; LS/RS_sf.
DR   NCBIfam; TIGR00114; lumazine-synth; 1.
DR   PANTHER; PTHR21058:SF0; 6,7-DIMETHYL-8-RIBITYLLUMAZINE SYNTHASE; 1.
DR   PANTHER; PTHR21058; 6,7-DIMETHYL-8-RIBITYLLUMAZINE SYNTHASE DMRL SYNTHASE LUMAZINE SYNTHASE; 1.
DR   Pfam; PF00885; DMRL_synthase; 1.
DR   SUPFAM; SSF52121; Lumazine synthase; 1.
PE   3: Inferred from homology;
KW   Riboflavin biosynthesis; Transferase.
FT   CHAIN           1..157
FT                   /note="6,7-dimethyl-8-ribityllumazine synthase"
FT                   /id="PRO_1000098175"
FT   ACT_SITE        89
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
FT   BINDING         22
FT                   /ligand="5-amino-6-(D-ribitylamino)uracil"
FT                   /ligand_id="ChEBI:CHEBI:15934"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
FT   BINDING         56..58
FT                   /ligand="5-amino-6-(D-ribitylamino)uracil"
FT                   /ligand_id="ChEBI:CHEBI:15934"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
FT   BINDING         81..83
FT                   /ligand="5-amino-6-(D-ribitylamino)uracil"
FT                   /ligand_id="ChEBI:CHEBI:15934"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
FT   BINDING         86..87
FT                   /ligand="(2S)-2-hydroxy-3-oxobutyl phosphate"
FT                   /ligand_id="ChEBI:CHEBI:58830"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
FT   BINDING         114
FT                   /ligand="5-amino-6-(D-ribitylamino)uracil"
FT                   /ligand_id="ChEBI:CHEBI:15934"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
FT   BINDING         128
FT                   /ligand="(2S)-2-hydroxy-3-oxobutyl phosphate"
FT                   /ligand_id="ChEBI:CHEBI:58830"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00178"
SQ   SEQUENCE   157 AA;  16412 MW;  00135FC75A7E3E0C CRC64;
     MKPLKGCPVA KDVRVAIVGS CFNSPIADRL VAGAQETFFD FGGDPSSLTI VRVPGAFEIP
     CAIKKLLSTS GQFHAVVACG VLIQGETSHY EHIADSVAAG VSRLSLDFCL PITFSVITAP
     NMEAAWERAG IKGPNLGASG MKTALEMASL FSLIGKE
//