ID   KHSE_BUCBP              Reviewed;         310 AA.
AC   P59568;
DT   11-APR-2003, integrated into UniProtKB/Swiss-Prot.
DT   11-APR-2003, sequence version 1.
DT   10-JUN-2026, entry version 128.
DE   RecName: Full=Homoserine kinase {ECO:0000255|HAMAP-Rule:MF_00384};
DE            Short=HK {ECO:0000255|HAMAP-Rule:MF_00384};
DE            Short=HSK {ECO:0000255|HAMAP-Rule:MF_00384};
DE            EC=2.7.1.39 {ECO:0000255|HAMAP-Rule:MF_00384};
GN   Name=thrB {ECO:0000255|HAMAP-Rule:MF_00384};
GN   OrderedLocusNames=bbp_182;
OS   Buchnera aphidicola subsp. Baizongia pistaciae (strain Bp).
OC   Bacteria; Pseudomonadati; Pseudomonadota; Gammaproteobacteria;
OC   Enterobacterales; Erwiniaceae; Buchnera.
OX   NCBI_TaxID=224915;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=Bp;
RX   PubMed=12522265; DOI=10.1073/pnas.0235981100;
RA   van Ham R.C.H.J., Kamerbeek J., Palacios C., Rausell C., Abascal F.,
RA   Bastolla U., Fernandez J.M., Jimenez L., Postigo M., Silva F.J.,
RA   Tamames J., Viguera E., Latorre A., Valencia A., Moran F., Moya A.;
RT   "Reductive genome evolution in Buchnera aphidicola.";
RL   Proc. Natl. Acad. Sci. U.S.A. 100:581-586(2003).
CC   -!- FUNCTION: Catalyzes the ATP-dependent phosphorylation of L-homoserine
CC       to L-homoserine phosphate. {ECO:0000255|HAMAP-Rule:MF_00384}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=L-homoserine + ATP = O-phospho-L-homoserine + ADP + H(+);
CC         Xref=Rhea:RHEA:13985, ChEBI:CHEBI:15378, ChEBI:CHEBI:30616,
CC         ChEBI:CHEBI:57476, ChEBI:CHEBI:57590, ChEBI:CHEBI:456216;
CC         EC=2.7.1.39; Evidence={ECO:0000255|HAMAP-Rule:MF_00384};
CC   -!- PATHWAY: Amino-acid biosynthesis; L-threonine biosynthesis; L-threonine
CC       from L-aspartate: step 4/5. {ECO:0000255|HAMAP-Rule:MF_00384}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000255|HAMAP-Rule:MF_00384}.
CC   -!- SIMILARITY: Belongs to the GHMP kinase family. Homoserine kinase
CC       subfamily. {ECO:0000255|HAMAP-Rule:MF_00384}.
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DR   EMBL; AE016826; AAO26914.1; -; Genomic_DNA.
DR   RefSeq; WP_011091315.1; NC_004545.1.
DR   AlphaFoldDB; P59568; -.
DR   SMR; P59568; -.
DR   STRING; 224915.bbp_182; -.
DR   KEGG; bab:bbp_182; -.
DR   eggNOG; COG0083; Bacteria.
DR   HOGENOM; CLU_041243_1_1_6; -.
DR   OrthoDB; 9769912at2; -.
DR   UniPathway; UPA00050; UER00064.
DR   Proteomes; UP000000601; Chromosome.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0005524; F:ATP binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0004413; F:homoserine kinase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0009088; P:L-threonine biosynthetic process; IEA:UniProtKB-UniRule.
DR   Gene3D; 3.30.230.10; -; 1.
DR   Gene3D; 3.30.70.890; GHMP kinase, C-terminal domain; 1.
DR   HAMAP; MF_00384; Homoser_kinase; 1.
DR   InterPro; IPR013750; GHMP_kinase_C_dom.
DR   InterPro; IPR036554; GHMP_kinase_C_sf.
DR   InterPro; IPR006204; GHMP_kinase_N_dom.
DR   InterPro; IPR006203; GHMP_knse_ATP-bd_CS.
DR   InterPro; IPR000870; Homoserine_kinase.
DR   InterPro; IPR020568; Ribosomal_Su5_D2-typ_SF.
DR   InterPro; IPR014721; Ribsml_uS5_D2-typ_fold_subgr.
DR   NCBIfam; NF002288; PRK01212.1-4; 1.
DR   NCBIfam; TIGR00191; thrB; 1.
DR   PANTHER; PTHR20861:SF1; HOMOSERINE KINASE; 1.
DR   PANTHER; PTHR20861; HOMOSERINE/4-DIPHOSPHOCYTIDYL-2-C-METHYL-D-ERYTHRITOL KINASE; 1.
DR   Pfam; PF08544; GHMP_kinases_C; 1.
DR   Pfam; PF00288; GHMP_kinases_N; 1.
DR   PIRSF; PIRSF000676; Homoser_kin; 1.
DR   PRINTS; PR00958; HOMSERKINASE.
DR   SUPFAM; SSF55060; GHMP Kinase, C-terminal domain; 1.
DR   SUPFAM; SSF54211; Ribosomal protein S5 domain 2-like; 1.
DR   PROSITE; PS00627; GHMP_KINASES_ATP; 1.
PE   3: Inferred from homology;
KW   Amino-acid biosynthesis; ATP-binding; Cytoplasm; Kinase;
KW   Nucleotide-binding; Reference proteome; Threonine biosynthesis;
KW   Transferase.
FT   CHAIN           1..310
FT                   /note="Homoserine kinase"
FT                   /id="PRO_0000156557"
FT   BINDING         91..101
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00384"
SQ   SEQUENCE   310 AA;  33953 MW;  D5650D9729131EAA CRC64;
     MIKIYAPASI GNVGVGFDVL GAAISPIDNS LLGDVITITS SKQFSLTSTG TFSNQLPKDI
     NKNIVKKCWT YFCKILKKNL PVSITLEKNM PIGSGLGSSA CSIVATVVAI NTFFNKPINN
     FELLKLMGKL EGKISGSVHY DNVAPSYLGG MQLIINKNDI VCQKISIFKN WLWVIAWPGI
     SISTEQARTL LPLQYSKKVC IQHSQNLAGF IHATYTHQSK LASMFMHDII AEPYRIKLLP
     YFLKTKQIII DMGAIACGIS GSGPAIFAVS DNLLTAKKIA TWLTNYYLTN DRGFVHICKI
     DTIGARKIGL
//