ID   SPPA_SYNY3              Reviewed;         610 AA.
AC   P73689;
DT   01-NOV-1997, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1997, sequence version 1.
DT   25-MAY-2022, entry version 132.
DE   RecName: Full=Protease 4;
DE            EC=3.4.21.-;
DE   AltName: Full=Endopeptidase IV;
DE   AltName: Full=Protease IV homolog;
DE   AltName: Full=Signal peptide peptidase;
GN   Name=sppA; OrderedLocusNames=sll1703;
OS   Synechocystis sp. (strain PCC 6803 / Kazusa).
OC   Bacteria; Cyanobacteria; Synechococcales; Merismopediaceae; Synechocystis;
OC   unclassified Synechocystis.
OX   NCBI_TaxID=1111708;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=PCC 6803 / Kazusa;
RX   PubMed=8905231; DOI=10.1093/dnares/3.3.109;
RA   Kaneko T., Sato S., Kotani H., Tanaka A., Asamizu E., Nakamura Y.,
RA   Miyajima N., Hirosawa M., Sugiura M., Sasamoto S., Kimura T., Hosouchi T.,
RA   Matsuno A., Muraki A., Nakazaki N., Naruo K., Okumura S., Shimpo S.,
RA   Takeuchi C., Wada T., Watanabe A., Yamada M., Yasuda M., Tabata S.;
RT   "Sequence analysis of the genome of the unicellular cyanobacterium
RT   Synechocystis sp. strain PCC6803. II. Sequence determination of the entire
RT   genome and assignment of potential protein-coding regions.";
RL   DNA Res. 3:109-136(1996).
CC   -!- FUNCTION: Digests cleaved signal peptides in vitro, its in vivo
CC       function is unknown. This activity is necessary to maintain proper
CC       secretion of mature proteins across the membrane (By similarity).
CC       {ECO:0000250}.
CC   -!- SUBUNIT: Homotetramer. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cell inner membrane {ECO:0000250}; Single-pass
CC       membrane protein {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the peptidase S49 family. {ECO:0000305}.
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DR   EMBL; BA000022; BAA17735.1; -; Genomic_DNA.
DR   PIR; S77177; S77177.
DR   AlphaFoldDB; P73689; -.
DR   SMR; P73689; -.
DR   IntAct; P73689; 2.
DR   STRING; 1148.1652816; -.
DR   PaxDb; P73689; -.
DR   EnsemblBacteria; BAA17735; BAA17735; BAA17735.
DR   KEGG; syn:sll1703; -.
DR   eggNOG; COG0616; Bacteria.
DR   InParanoid; P73689; -.
DR   OMA; DPKGQYL; -.
DR   PhylomeDB; P73689; -.
DR   Proteomes; UP000001425; Chromosome.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0005886; C:plasma membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0008236; F:serine-type peptidase activity; IEA:UniProtKB-KW.
DR   GO; GO:0006465; P:signal peptide processing; IEA:InterPro.
DR   CDD; cd07023; S49_Sppa_N_C; 1.
DR   InterPro; IPR029045; ClpP/crotonase-like_dom_sf.
DR   InterPro; IPR004634; Pept_S49_pIV.
DR   InterPro; IPR004635; Pept_S49_SppA.
DR   InterPro; IPR002142; Peptidase_S49.
DR   Pfam; PF01343; Peptidase_S49; 2.
DR   PIRSF; PIRSF001217; Protease_4_SppA; 1.
DR   SUPFAM; SSF52096; SSF52096; 2.
DR   TIGRFAMs; TIGR00705; SppA_67K; 1.
DR   TIGRFAMs; TIGR00706; SppA_dom; 1.
PE   3: Inferred from homology;
KW   Cell inner membrane; Cell membrane; Hydrolase; Membrane; Protease;
KW   Reference proteome; Serine protease; Transmembrane; Transmembrane helix.
FT   CHAIN           1..610
FT                   /note="Protease 4"
FT                   /id="PRO_0000171440"
FT   TOPO_DOM        1..16
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        17..37
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        38..610
FT                   /note="Periplasmic"
FT                   /evidence="ECO:0000255"
FT   ACT_SITE        195
FT                   /note="Proton donor/acceptor"
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        401
FT                   /note="Nucleophile"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   610 AA;  67212 MW;  7DE5DA3CD4389C05 CRC64;
     MKNFFQQMVA SFFGTLAAIV VLLSLGATGL VLLFILVSAE ADPVLEEKTA LILDLAIPIQ
     DTSPTLSLQQ SLLGNQEEIL PLRTVVNAIE KAAEDDRIVA LLIDGRRSNQ VDGYANLSEV
     QQALIKFKQS GKKIVAYGLN YSELGYYLAA TADTILINPM GGVEINGLGA QPIFFTGALA
     KAGIGVQTLR VGSYKGAVEP YTRENLSPEN RQQQQLLLNQ IWQIYLTSVA NNRSLTVPQL
     QAIASDQGLL FADIALREKL VDKVTYWDEV LAELKQAGVW INDPEKIEEQ EEDKEFRKIS
     LAEYHRLQNW ETENHDQDPK IAIVYLEGSI VNGRGTWENI GGDRYGELLR TIRQDDDIKA
     VVLRINSPGG SASAADIIWR EVELLQAQKP VIISMGNVAA SGGYWIATAG EKIVAQPNTV
     TGSIGVFSIL FNVENLGDRL GLNWDEVATG ELANVGSSIK PKTELELAIF QRSVDQVYEI
     FLDKVGRARN LSPTALDSVA QGRVWTGLAA QKVGLVDQLG GLQTAVNLAA AQAELGEQWQ
     VKEYPTPRGL NSLLWNNLIH GLTETNSVVL PPFLRTNWQQ LEREWAELAQ FNDPQGIYAR
     LPFSWHFLNP