HACB_METTH
ID HACB_METTH Reviewed; 170 AA.
AC O26917;
DT 15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT 01-JAN-1998, sequence version 1.
DT 25-MAY-2022, entry version 127.
DE RecName: Full=Methanogen homoaconitase small subunit;
DE Short=HACN;
DE EC=4.2.1.114 {ECO:0000250|UniProtKB:Q58667};
DE AltName: Full=Homoaconitate hydratase;
GN Name=hacB; OrderedLocusNames=MTH_829;
OS Methanothermobacter thermautotrophicus (strain ATCC 29096 / DSM 1053 / JCM
OS 10044 / NBRC 100330 / Delta H) (Methanobacterium thermoautotrophicum).
OC Archaea; Euryarchaeota; Methanomada group; Methanobacteria;
OC Methanobacteriales; Methanobacteriaceae; Methanothermobacter.
OX NCBI_TaxID=187420;
RN [1]
RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC STRAIN=ATCC 29096 / DSM 1053 / JCM 10044 / NBRC 100330 / Delta H;
RX PubMed=9371463; DOI=10.1128/jb.179.22.7135-7155.1997;
RA Smith D.R., Doucette-Stamm L.A., Deloughery C., Lee H.-M., Dubois J.,
RA Aldredge T., Bashirzadeh R., Blakely D., Cook R., Gilbert K., Harrison D.,
RA Hoang L., Keagle P., Lumm W., Pothier B., Qiu D., Spadafora R., Vicare R.,
RA Wang Y., Wierzbowski J., Gibson R., Jiwani N., Caruso A., Bush D.,
RA Safer H., Patwell D., Prabhakar S., McDougall S., Shimer G., Goyal A.,
RA Pietrovski S., Church G.M., Daniels C.J., Mao J.-I., Rice P., Noelling J.,
RA Reeve J.N.;
RT "Complete genome sequence of Methanobacterium thermoautotrophicum deltaH:
RT functional analysis and comparative genomics.";
RL J. Bacteriol. 179:7135-7155(1997).
CC -!- FUNCTION: Component of a hydro-lyase with broad substrate specificity
CC for cis-unsaturated tricarboxylic acids. Catalyzes both the reversible
CC dehydration of (R)-homocitrate ((R)-2-hydroxybutane-1,2,4-
CC tricarboxylate) to produce cis-homoaconitate ((Z)-but-1-ene-1,2,4-
CC tricarboxylate), and its hydration to homoisocitrate ((1R,2S)-1-
CC hydroxybutane-1,2,4-tricarboxylate). Is also able to hydrate the
CC analogous longer chain substrates cis-homo(2)-aconitate, cis-homo(3)-
CC aconitate. These reactions are part of the biosynthesis pathway of
CC coenzyme B. {ECO:0000250|UniProtKB:Q58667}.
CC -!- CATALYTIC ACTIVITY:
CC Reaction=(2R)-homocitrate = (2R,3S)-homoisocitrate;
CC Xref=Rhea:RHEA:32303, ChEBI:CHEBI:15404, ChEBI:CHEBI:58884;
CC EC=4.2.1.114; Evidence={ECO:0000250|UniProtKB:Q58667};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:32304;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=(2R)-homocitrate = cis-homoaconitate + H2O;
CC Xref=Rhea:RHEA:26101, ChEBI:CHEBI:15377, ChEBI:CHEBI:58174,
CC ChEBI:CHEBI:58884; Evidence={ECO:0000250|UniProtKB:Q58667};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:26102;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=(2R,3S)-homoisocitrate = cis-homoaconitate + H2O;
CC Xref=Rhea:RHEA:15485, ChEBI:CHEBI:15377, ChEBI:CHEBI:15404,
CC ChEBI:CHEBI:58174; Evidence={ECO:0000250|UniProtKB:Q58667};
CC PhysiologicalDirection=right-to-left; Xref=Rhea:RHEA:15487;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=cis-(homo)2aconitate + H2O = (2R,3S)-iso(homo)2citrate;
CC Xref=Rhea:RHEA:68416, ChEBI:CHEBI:15377, ChEBI:CHEBI:72710,
CC ChEBI:CHEBI:72722; EC=4.2.1.114;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:68417;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=cis-(homo)3aconitate + H2O = (2R,3S)-iso(homo)3citrate;
CC Xref=Rhea:RHEA:68420, ChEBI:CHEBI:15377, ChEBI:CHEBI:72712,
CC ChEBI:CHEBI:177881; EC=4.2.1.114;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:68421;
CC Evidence={ECO:0000250|UniProtKB:Q58667};
CC -!- PATHWAY: Organic acid metabolism; 2-oxosuberate biosynthesis.
CC {ECO:0000250|UniProtKB:Q58667}.
CC -!- SUBUNIT: Heterotetramer of 2 HacA and 2 HacB proteins.
CC {ECO:0000250|UniProtKB:Q58667}.
CC -!- SIMILARITY: Belongs to the LeuD family. LeuD type 2 subfamily.
CC {ECO:0000305}.
CC -!- CAUTION: Functional assignment as methanogen HACN has been made based
CC on the presence of the YLRT motif involved in substrate specificity as
CC discussed in PubMed:20170198. {ECO:0000305}.
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DR EMBL; AE000666; AAB85327.1; -; Genomic_DNA.
DR PIR; E69210; E69210.
DR RefSeq; WP_010876462.1; NC_000916.1.
DR AlphaFoldDB; O26917; -.
DR SMR; O26917; -.
DR STRING; 187420.MTH_829; -.
DR PRIDE; O26917; -.
DR EnsemblBacteria; AAB85327; AAB85327; MTH_829.
DR GeneID; 1471237; -.
DR KEGG; mth:MTH_829; -.
DR PATRIC; fig|187420.15.peg.812; -.
DR HOGENOM; CLU_081378_1_1_2; -.
DR OMA; DDVNTDY; -.
DR UniPathway; UPA00919; -.
DR Proteomes; UP000005223; Chromosome.
DR GO; GO:0004409; F:homoaconitate hydratase activity; IEA:UniProtKB-UniRule.
DR GO; GO:0019298; P:coenzyme B biosynthetic process; IEA:UniProtKB-UniRule.
DR CDD; cd01577; IPMI_Swivel; 1.
DR Gene3D; 3.20.19.10; -; 1.
DR HAMAP; MF_01032; LeuD_type2; 1.
DR InterPro; IPR015928; Aconitase/3IPM_dehydase_swvl.
DR InterPro; IPR000573; AconitaseA/IPMdHydase_ssu_swvl.
DR InterPro; IPR033940; IPMI_Swivel.
DR InterPro; IPR011827; LeuD_type2/HacB/DmdB.
DR Pfam; PF00694; Aconitase_C; 1.
DR TIGRFAMs; TIGR02087; LEUD_arch; 1.
PE 3: Inferred from homology;
KW Lyase; Reference proteome.
FT CHAIN 1..170
FT /note="Methanogen homoaconitase small subunit"
FT /id="PRO_0000141942"
FT MOTIF 26..29
FT /note="YLRT"
FT SITE 28
FT /note="Critical for substrate specificity"
FT /evidence="ECO:0000250"
SQ SEQUENCE 170 AA; 18651 MW; BC07146AF7585215 CRC64;
MEGIIRGRVW RFGDNVDTDM IIPGRYLRTF SLDELASHVM EGARPEFASQ VRKGDIIVAG
RNFGCGSSRE QAPVALKHAG VVAIIAESFA RIFYRNAINI GLPVIMAKVD ADDGDEVSID
LRSGQIRNLT AGSEYRMKPF NDYMLSILED GGLVNHYLKT IDTGISGDEG
