ID   ILVH_BUCAI              Reviewed;         158 AA.
AC   P57320;
DT   01-DEC-2000, integrated into UniProtKB/Swiss-Prot.
DT   01-DEC-2000, sequence version 1.
DT   03-AUG-2022, entry version 107.
DE   RecName: Full=Acetolactate synthase small subunit;
DE            EC=2.2.1.6;
DE   AltName: Full=Acetohydroxy-acid synthase small subunit;
DE            Short=AHAS;
DE            Short=ALS;
GN   Name=ilvH; OrderedLocusNames=BU225;
OS   Buchnera aphidicola subsp. Acyrthosiphon pisum (strain APS) (Acyrthosiphon
OS   pisum symbiotic bacterium).
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Erwiniaceae; Buchnera.
OX   NCBI_TaxID=107806;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=APS;
RX   PubMed=10993077; DOI=10.1038/35024074;
RA   Shigenobu S., Watanabe H., Hattori M., Sakaki Y., Ishikawa H.;
RT   "Genome sequence of the endocellular bacterial symbiont of aphids Buchnera
RT   sp. APS.";
RL   Nature 407:81-86(2000).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H(+) + 2 pyruvate = (2S)-2-acetolactate + CO2;
CC         Xref=Rhea:RHEA:25249, ChEBI:CHEBI:15361, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:16526, ChEBI:CHEBI:58476; EC=2.2.1.6;
CC   -!- PATHWAY: Amino-acid biosynthesis; L-isoleucine biosynthesis; L-
CC       isoleucine from 2-oxobutanoate: step 1/4.
CC   -!- PATHWAY: Amino-acid biosynthesis; L-valine biosynthesis; L-valine from
CC       pyruvate: step 1/4.
CC   -!- SUBUNIT: Dimer of large and small chains. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the acetolactate synthase small subunit family.
CC       {ECO:0000305}.
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DR   EMBL; BA000003; BAB12941.1; -; Genomic_DNA.
DR   RefSeq; NP_240055.1; NC_002528.1.
DR   RefSeq; WP_010896015.1; NC_002528.1.
DR   AlphaFoldDB; P57320; -.
DR   SMR; P57320; -.
DR   STRING; 107806.10038906; -.
DR   EnsemblBacteria; BAB12941; BAB12941; BAB12941.
DR   KEGG; buc:BU225; -.
DR   PATRIC; fig|107806.10.peg.238; -.
DR   eggNOG; COG0440; Bacteria.
DR   HOGENOM; CLU_055003_1_3_6; -.
DR   OMA; EPYGIKE; -.
DR   UniPathway; UPA00047; UER00055.
DR   UniPathway; UPA00049; UER00059.
DR   Proteomes; UP000001806; Chromosome.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProt.
DR   GO; GO:0003984; F:acetolactate synthase activity; IEA:UniProtKB-EC.
DR   GO; GO:1990610; F:acetolactate synthase regulator activity; IEA:InterPro.
DR   GO; GO:0009097; P:isoleucine biosynthetic process; IEA:UniProtKB-UniPathway.
DR   GO; GO:0009099; P:valine biosynthetic process; IEA:UniProtKB-UniPathway.
DR   CDD; cd04878; ACT_AHAS; 1.
DR   Gene3D; 3.30.70.1150; -; 1.
DR   InterPro; IPR004789; Acetalactate_synth_ssu.
DR   InterPro; IPR027271; Acetolactate_synth/TF_NikR_C.
DR   InterPro; IPR019455; Acetolactate_synth_ssu_C.
DR   InterPro; IPR045865; ACT-like_dom_sf.
DR   InterPro; IPR002912; ACT_dom.
DR   InterPro; IPR039557; AHAS_ACT.
DR   PANTHER; PTHR30239; PTHR30239; 1.
DR   Pfam; PF10369; ALS_ss_C; 1.
DR   SUPFAM; SSF55021; SSF55021; 2.
DR   TIGRFAMs; TIGR00119; acolac_sm; 1.
DR   PROSITE; PS51671; ACT; 1.
PE   3: Inferred from homology;
KW   Amino-acid biosynthesis; Branched-chain amino acid biosynthesis;
KW   Reference proteome; Transferase.
FT   CHAIN           1..158
FT                   /note="Acetolactate synthase small subunit"
FT                   /id="PRO_0000151407"
FT   DOMAIN          4..78
FT                   /note="ACT"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01007"
SQ   SEQUENCE   158 AA;  17845 MW;  74E4EC378D5B6C6B CRC64;
     MRRILSILLE NESGALSRVI GLFSQRGYNI ETITLAPTED PTLSKMTIQT VGNEKAIEQI
     EKQLHKLIDV LRVVQIGQSS HIEREIVLLK VQINNHRRDD IKHITEVFRG QIVDITSATY
     ILQLSGTTKK IDAFLKIIRN FSEIIEVTRS GIVGISRG