ID   TCMN_STRGA              Reviewed;         494 AA.
AC   P16559;
DT   01-AUG-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1995, sequence version 2.
DT   04-NOV-2026, entry version 111.
DE   RecName: Full=Tetracenomycin biosynthesis bifunctional cyclase/O-methyl transferase TcmN {ECO:0000305};
DE            EC=2.1.1.- {ECO:0000269|PubMed:8692863};
DE            EC=2.3.1.235 {ECO:0000269|PubMed:9609708};
DE   AltName: Full=Multifunctional cyclase-dehydratase-3-O-methyl transferase TcmN {ECO:0000303|PubMed:1548230};
DE   Includes:
DE     RecName: Full=Tetracenomycin polyketide synthase cyclase TcmN {ECO:0000305};
DE     AltName: Full=TCM PKS {ECO:0000305};
DE     AltName: Full=TcmN polyketide cyclase {ECO:0000303|PubMed:8692863};
DE     AltName: Full=Tetracenomycin aromatase/cyclase {ECO:0000303|PubMed:34139289};
DE              Short=Tcm ARO/CYC {ECO:0000303|PubMed:18388203};
DE              Short=Tetracenomycin ARO/CYC {ECO:0000303|PubMed:18388203};
DE   Includes:
DE     RecName: Full=Tcm D3 O-methyltransferase {ECO:0000303|PubMed:8692863};
GN   Name=tcmN {ECO:0000303|PubMed:1548230};
OS   Streptomyces glaucescens.
OC   Bacteria; Bacillati; Actinomycetota; Actinomycetes; Kitasatosporales;
OC   Streptomycetaceae; Streptomyces.
OX   NCBI_TaxID=1907;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, PATHWAY, AND DOMAIN.
RC   STRAIN=DSM 40716 / ETH 22794 / Tue 49;
RX   PubMed=1548230; DOI=10.1128/jb.174.6.1810-1820.1992;
RA   Summers R.G., Wendt-Pienkowski E., Motamedi H., Hutchinson C.R.;
RT   "Nucleotide sequence of the tcmII-tcmIV region of the tetracenomycin C
RT   biosynthetic gene cluster of Streptomyces glaucescens and evidence that the
RT   tcmN gene encodes a multifunctional cyclase-dehydratase-O-methyl
RT   transferase.";
RL   J. Bacteriol. 174:1810-1820(1992).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-17.
RC   STRAIN=DSM 40716 / ETH 22794 / Tue 49;
RX   PubMed=2684656; DOI=10.1002/j.1460-2075.1989.tb08414.x;
RA   Bibb M.J., Biro S., Motamedi H., Collins J.F., Hutchinson C.R.;
RT   "Analysis of the nucleotide sequence of the Streptomyces glaucescens tcmI
RT   genes provides key information about the enzymology of polyketide
RT   antibiotic biosynthesis.";
RL   EMBO J. 8:2727-2736(1989).
RN   [3]
RP   FUNCTION, AND SUBUNIT.
RC   STRAIN=DSM 40716 / ETH 22794 / Tue 49;
RX   PubMed=8248801; DOI=10.1126/science.8248801;
RA   Shen B., Hutchinson C.R.;
RT   "Enzymatic synthesis of a bacterial polyketide from acetyl and malonyl
RT   coenzyme A.";
RL   Science 262:1535-1540(1993).
RN   [4]
RP   PROTEIN SEQUENCE OF 2-23, FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES, SUBUNIT,
RP   DOMAIN, AND DISRUPTION PHENOTYPE.
RC   STRAIN=DSM 40716 / ETH 22794 / Tue 49;
RX   PubMed=8692863; DOI=10.1073/pnas.93.13.6600;
RA   Shen B., Hutchinson C.R.;
RT   "Deciphering the mechanism for the assembly of aromatic polyketides by a
RT   bacterial polyketide synthase.";
RL   Proc. Natl. Acad. Sci. U.S.A. 93:6600-6604(1996).
RN   [5]
RP   FUNCTION, CATALYTIC ACTIVITY, AND PATHWAY.
RC   STRAIN=DSM 40716 / ETH 22794 / Tue 49;
RX   PubMed=9609708; DOI=10.1021/bi980466i;
RA   Bao W., Wendt-Pienkowski E., Hutchinson C.R.;
RT   "Reconstitution of the iterative type II polyketide synthase for
RT   tetracenomycin F2 biosynthesis.";
RL   Biochemistry 37:8132-8138(1998).
RN   [6] {ECO:0007744|PDB:2RER, ECO:0007744|PDB:2RES, ECO:0007744|PDB:2REZ}
RP   X-RAY CRYSTALLOGRAPHY, FUNCTION, DOMAIN, ACTIVE SITE, AND MUTAGENESIS OF
RP   GLU-34; TYR-35; TRP-63; ARG-69; TRP-108; GLN-110 AND ASN-136.
RX   PubMed=18388203; DOI=10.1073/pnas.0709223105;
RA   Ames B.D., Korman T.P., Zhang W., Smith P., Vu T., Tang Y., Tsai S.C.;
RT   "Crystal structure and functional analysis of tetracenomycin ARO/CYC:
RT   implications for cyclization specificity of aromatic polyketides.";
RL   Proc. Natl. Acad. Sci. U.S.A. 105:5349-5354(2008).
RN   [7] {ECO:0007744|PDB:3TVQ}
RP   X-RAY CRYSTALLOGRAPHY IN COMPLEX WITH PLANT POLYKETIDE TAXIFOLIN, AND
RP   ACTIVE SITE.
RX   PubMed=22432862; DOI=10.1021/bi201705q;
RA   Lee M.Y., Ames B.D., Tsai S.C.;
RT   "Insight into the molecular basis of aromatic polyketide cyclization:
RT   crystal structure and in vitro characterization of WhiE-ORFVI.";
RL   Biochemistry 51:3079-3091(2012).
RN   [8]
RP   STRUCTURE BY NMR, MOLECULAR DYNAMICS SIMULATIONS, BIOPHYSICOCHEMICAL
RP   PROPERTIES, AND DOMAIN.
RX   PubMed=34139289; DOI=10.1016/j.bbagen.2021.129949;
RA   Valadares V.S., Martins L.C., Roman E.A., Valente A.P., Cino E.A.,
RA   Moraes A.H.;
RT   "Conformational dynamics of Tetracenomycin aromatase/cyclase regulate
RT   polyketide binding and enzyme aggregation propensity.";
RL   Biochim. Biophys. Acta 1865:129949-129949(2021).
CC   -!- FUNCTION: Involved in the biosynthesis of tetracenomycin C (TCM C)
CC       (PubMed:1548230, PubMed:9609708). Part of a type II polyketide synthase
CC       (PKS) that catalyzes the synthesis of tetracenomycin F2 (TCM F2), a
CC       precursor of TCM C, from malonyl-CoA (PubMed:8248801, PubMed:9609708).
CC       The TcmN N-terminal domain, when coupled with the other components of
CC       the PKS, catalyzes the cyclization and aromatization of the linear
CC       polyketide intermediate (PubMed:1548230, PubMed:18388203,
CC       PubMed:8248801, PubMed:8692863). Catalyzes the cyclization of the first
CC       and second rings (PubMed:18388203). In addition, the C-terminal domain
CC       acts as a methyltransferase (PubMed:1548230, PubMed:8692863). It
CC       catalyzes the specific O-methylation of tetracenomycin D3 (TCM D3) to
CC       TCM B3, using S-adenosyl-L-methionine as the methyl donor
CC       (PubMed:8692863). {ECO:0000269|PubMed:1548230,
CC       ECO:0000269|PubMed:18388203, ECO:0000269|PubMed:8248801,
CC       ECO:0000269|PubMed:8692863, ECO:0000269|PubMed:9609708}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=10 malonyl-CoA + 8 H(+) = tetracenomycin F2 + 10 CO2 + 10 CoA
CC         + 2 H2O; Xref=Rhea:RHEA:21348, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:16526, ChEBI:CHEBI:57287, ChEBI:CHEBI:57384,
CC         ChEBI:CHEBI:77982; EC=2.3.1.235;
CC         Evidence={ECO:0000269|PubMed:9609708};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:21349;
CC         Evidence={ECO:0000269|PubMed:9609708};
CC   -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC       pH dependence:
CC         Optimum pH is 8.0 for methyltransferase activity.
CC         {ECO:0000269|PubMed:8692863};
CC       Temperature dependence:
CC         Thermal resistance is enhanced at low protein and high salt
CC         concentrations, is pH-dependent and denaturation is irreversible.
CC         {ECO:0000269|PubMed:34139289};
CC   -!- PATHWAY: Antibiotic biosynthesis; tetracenomycin C biosynthesis.
CC       {ECO:0000269|PubMed:1548230, ECO:0000269|PubMed:9609708}.
CC   -!- SUBUNIT: The tetracenomycin polyketide synthase (TCM PKS) is composed
CC       of a ketosynthase complex (TcmKL), an acyl carrier protein (TcmM), a
CC       cyclase (TcmN) and a probable second cyclase (TcmJ) (PubMed:8248801,
CC       PubMed:8692863). TcmN is a homodimer in solution (PubMed:8692863).
CC       {ECO:0000269|PubMed:8248801, ECO:0000269|PubMed:8692863}.
CC   -!- DOMAIN: This multifunction enzyme is comprised of two structurally and
CC       functionally independent domains (PubMed:1548230, PubMed:8692863).
CC       Contains a highly conserved interior pocket (PubMed:18388203). The
CC       size, shape and composition of the pocket are important to orient and
CC       specifically fold the polyketide chain (PubMed:18388203). The
CC       accessibility of the hydrophobic cavity is regulated by a dynamic
CC       equilibrium between open and closed states (PubMed:34139289).
CC       {ECO:0000269|PubMed:1548230, ECO:0000269|PubMed:18388203,
CC       ECO:0000269|PubMed:34139289, ECO:0000269|PubMed:8692863}.
CC   -!- DISRUPTION PHENOTYPE: In the absence of TcmN, the linear polyketide
CC       intermediate formed by the minimal PKS consisting of the TcmJKLM
CC       proteins undergoes spontaneous cyclization to form some TCM F2 as well
CC       as SEK15 and many other aberrant shunt products.
CC       {ECO:0000269|PubMed:8692863}.
CC   -!- SIMILARITY: In the C-terminal section; belongs to the class I-like SAM-
CC       binding methyltransferase superfamily. Cation-independent O-
CC       methyltransferase family. {ECO:0000255|PROSITE-ProRule:PRU01020}.
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DR   EMBL; M80674; AAA67518.1; -; Genomic_DNA.
DR   EMBL; X15312; CAB38457.1; -; Genomic_DNA.
DR   PIR; B42276; S27696.
DR   RefSeq; WP_244315260.1; NZ_CP009438.1.
DR   PDB; 2RER; X-ray; 1.90 A; A=1-170.
DR   PDB; 2RES; X-ray; 2.20 A; A=1-170.
DR   PDB; 2REZ; X-ray; 1.95 A; A=1-154.
DR   PDB; 3TVQ; X-ray; 1.67 A; A=1-169.
DR   AlphaFoldDB; P16559; -.
DR   MDposit; P16559; -.
DR   SMR; P16559; -.
DR   STRING; 1907.SGLAU_26370; -.
DR   eggNOG; COG2226; Bacteria.
DR   eggNOG; COG2867; Bacteria.
DR   OMA; ACCACSF; -.
DR   BioCyc; MetaCyc:MONOMER-18604; -.
DR   BRENDA; 2.3.1.235; 6020.
DR   UniPathway; UPA00174; -.
DR   EvolutionaryTrace; P16559; -.
DR   GO; GO:0008171; F:O-methyltransferase activity; IEA:InterPro.
DR   GO; GO:0046983; F:protein dimerization activity; IEA:InterPro.
DR   CDD; cd02440; AdoMet_MTases; 1.
DR   CDD; cd08860; TcmN_ARO-CYC_like; 1.
DR   Gene3D; 1.10.287.1350; -; 1.
DR   Gene3D; 3.30.530.20; -; 1.
DR   Gene3D; 3.40.50.150; Vaccinia Virus protein VP39; 1.
DR   Gene3D; 1.10.10.10; Winged helix-like DNA-binding domain superfamily/Winged helix DNA-binding domain; 1.
DR   InterPro; IPR016461; COMT-like.
DR   InterPro; IPR012967; COMT-like_dimerisation.
DR   InterPro; IPR001077; COMT_C.
DR   InterPro; IPR005031; COQ10_START.
DR   InterPro; IPR029063; SAM-dependent_MTases_sf.
DR   InterPro; IPR023393; START-like_dom_sf.
DR   InterPro; IPR036388; WH-like_DNA-bd_sf.
DR   InterPro; IPR036390; WH_DNA-bd_sf.
DR   PANTHER; PTHR43712:SF2; O-METHYLTRANSFERASE CICE; 1.
DR   PANTHER; PTHR43712; PUTATIVE (AFU_ORTHOLOGUE AFUA_4G14580)-RELATED; 1.
DR   Pfam; PF08100; Dimerisation; 1.
DR   Pfam; PF00891; Methyltransf_2; 1.
DR   Pfam; PF03364; Polyketide_cyc; 1.
DR   SUPFAM; SSF55961; Bet v1-like; 1.
DR   SUPFAM; SSF53335; S-adenosyl-L-methionine-dependent methyltransferases; 1.
DR   SUPFAM; SSF46785; Winged helix' DNA-binding domain; 1.
DR   PROSITE; PS51683; SAM_OMT_II; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Antibiotic biosynthesis; Direct protein sequencing;
KW   Methyltransferase; Multifunctional enzyme; S-adenosyl-L-methionine;
KW   Transferase.
FT   INIT_MET        1
FT                   /note="Removed"
FT                   /evidence="ECO:0000269|PubMed:8692863"
FT   CHAIN           2..494
FT                   /note="Tetracenomycin biosynthesis bifunctional cyclase/O-
FT                   methyl transferase TcmN"
FT                   /id="PRO_0000072456"
FT   REGION          11..140
FT                   /note="Polyketide cyclase"
FT                   /evidence="ECO:0000305"
FT   REGION          169..494
FT                   /note="Methyltransferase"
FT                   /evidence="ECO:0000305"
FT   ACT_SITE        67
FT                   /note="Proton acceptor; for cyclase activity"
FT                   /evidence="ECO:0000305|PubMed:22432862"
FT   ACT_SITE        69
FT                   /note="Proton donor; for cyclase activity"
FT                   /evidence="ECO:0000305|PubMed:18388203,
FT                   ECO:0000305|PubMed:22432862"
FT   ACT_SITE        82
FT                   /note="Proton donor; for cyclase activity"
FT                   /evidence="ECO:0000305|PubMed:18388203,
FT                   ECO:0000305|PubMed:22432862"
FT   ACT_SITE        405
FT                   /note="Proton acceptor; for methyltransferase activity"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         358
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         384..386
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   MUTAGEN         34
FT                   /note="E->A,Q: Decrease in the production of the first
FT                   ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         35
FT                   /note="Y->A: Abolishes the production of the first ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         35
FT                   /note="Y->T: Strong decrease in the production of the first
FT                   ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         63
FT                   /note="W->N: Decrease in the production of the first ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         69
FT                   /note="R->A,D: Abolishes the production of the first ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         108
FT                   /note="W->A,L: Strong decrease in the production of the
FT                   first ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         110
FT                   /note="Q->H: Strong decrease in the production of the first
FT                   ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   MUTAGEN         136
FT                   /note="N->A: Decrease in the production of the first ring."
FT                   /evidence="ECO:0000269|PubMed:18388203"
FT   CONFLICT        15
FT                   /note="F -> E (in Ref. 4; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   STRAND          3..13
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   HELIX           15..22
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   HELIX           25..27
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   HELIX           28..31
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   STRAND          35..44
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   STRAND          47..54
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   STRAND          64..72
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   HELIX           73..75
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   STRAND          77..84
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   STRAND          88..100
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   STRAND          103..114
FT                   /evidence="ECO:0007829|PDB:3TVQ"
FT   HELIX           122..151
FT                   /evidence="ECO:0007829|PDB:3TVQ"
SQ   SEQUENCE   494 AA;  55930 MW;  6E153D32782F66B5 CRC64;
     MAARTDNSIV VNAPFELVWD VTNDIEAWPE LFSEYAEAEI LRQDGDGFDF RLKTRPDANG
     RVWEWVSHRV PDKGSRTVRA HRVETGPFAY MNLHWTYRAV AGGTEMRWVQ EFDMKPGAPF
     DNAHMTAHLN TTTRANMERI KKIIEDRHRE GQRTPASVLP TELHAQQLLL LAASGRLARI
     VHVLTELRIA DLLADGPRHV AELAKETDTH ELSLYRVLRS AASVGVFAEG PVRTFSATPL
     SDGLRTGNPD GVLPLVKYNN MELTRRPYDE IMHSVRTGEP AFRRVFGSSF FEHLEANPEA
     GEFFERFMAH WSRRLVLDGL ADQGMERFSR IADLGGGDGW FLAQILRRHP HATGLLMDLP
     RVAASAGPVL EEAKVADRVT VLPGDFFTDP VPTGYDAYLF KGVLHNWSDE RAVTVLRRVR
     EAIGDDDARL LIFDQVMAPE NEWDHAKLLD IDMLVLFGGR ERVLAEWRQL LLEADFDIVN
     TPSHTWTTLE CRPV
//