ID   RBS_PROHO               Reviewed;         109 AA.
AC   P27569;
DT   01-AUG-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1992, sequence version 1.
DT   25-MAY-2022, entry version 80.
DE   RecName: Full=Ribulose bisphosphate carboxylase small subunit {ECO:0000255|HAMAP-Rule:MF_00859};
DE            Short=RuBisCO small subunit {ECO:0000255|HAMAP-Rule:MF_00859};
GN   Name=cbbS {ECO:0000255|HAMAP-Rule:MF_00859};
GN   Synonyms=rbcS {ECO:0000255|HAMAP-Rule:MF_00859};
OS   Prochlorothrix hollandica.
OC   Bacteria; Cyanobacteria; Pseudanabaenales; Prochlorotrichaceae;
OC   Prochlorothrix.
OX   NCBI_TaxID=1223;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=1904095; DOI=10.1007/bf02101278;
RA   Morden C.W., Golden S.S.;
RT   "Sequence analysis and phylogenetic reconstruction of the genes encoding
RT   the large and small subunits of ribulose-1,5-bisphosphate
RT   carboxylase/oxygenase from the chlorophyll b-containing prokaryote
RT   Prochlorothrix hollandica.";
RL   J. Mol. Evol. 32:379-395(1991).
CC   -!- FUNCTION: RuBisCO catalyzes two reactions: the carboxylation of D-
CC       ribulose 1,5-bisphosphate, the primary event in carbon dioxide
CC       fixation, as well as the oxidative fragmentation of the pentose
CC       substrate in the photorespiration process. Both reactions occur
CC       simultaneously and in competition at the same active site. Although the
CC       small subunit is not catalytic it is essential for maximal activity.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- SUBUNIT: Heterohexadecamer of 8 large and 8 small subunits.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- SUBCELLULAR LOCATION: Carboxysome {ECO:0000250|UniProtKB:Q31NB2,
CC       ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- MISCELLANEOUS: The basic functional RuBisCO is composed of a large
CC       chain homodimer in a 'head-to-tail' conformation. In form I RuBisCO
CC       this homodimer is arranged in a barrel-like tetramer with the small
CC       subunits forming a tetrameric 'cap' on each end of the 'barrel'.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- SIMILARITY: Belongs to the RuBisCO small chain family.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
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DR   EMBL; X57359; CAA40633.1; -; Genomic_DNA.
DR   PIR; S16437; S16437.
DR   AlphaFoldDB; P27569; -.
DR   SMR; P27569; -.
DR   GO; GO:0031470; C:carboxysome; IEA:UniProtKB-SubCell.
DR   GO; GO:0009853; P:photorespiration; IEA:UniProtKB-KW.
DR   GO; GO:0019253; P:reductive pentose-phosphate cycle; IEA:UniProtKB-KW.
DR   CDD; cd03527; RuBisCO_small; 1.
DR   Gene3D; 3.30.190.10; -; 1.
DR   HAMAP; MF_00859; RuBisCO_S_bact; 1.
DR   InterPro; IPR024681; RuBisCO_ssu.
DR   InterPro; IPR000894; RuBisCO_ssu_dom.
DR   InterPro; IPR036385; RuBisCO_ssu_sf.
DR   PANTHER; PTHR31262; PTHR31262; 1.
DR   Pfam; PF00101; RuBisCO_small; 1.
DR   PRINTS; PR00152; RUBISCOSMALL.
DR   SMART; SM00961; RuBisCO_small; 1.
DR   SUPFAM; SSF55239; SSF55239; 1.
PE   3: Inferred from homology;
KW   Bacterial microcompartment; Calvin cycle; Carbon dioxide fixation;
KW   Carboxysome; Photorespiration; Photosynthesis.
FT   CHAIN           1..109
FT                   /note="Ribulose bisphosphate carboxylase small subunit"
FT                   /id="PRO_0000198617"
SQ   SEQUENCE   109 AA;  12963 MW;  9A17AE63AACDD5BE CRC64;
     MKTLPKERRY ETLSYLPPLS DQQIARQIEY MVREGYIPAV EFNEDSDATT CYWTMWKLPL
     FHATSTQEVL GEVRECRTEY PNCYIRVVGF DNIKQCQSVS FIVHKPNRY