ID   SSRP_LACLA              Reviewed;         155 AA.
AC   Q9CEW2;
DT   27-APR-2001, integrated into UniProtKB/Swiss-Prot.
DT   27-APR-2001, sequence version 1.
DT   25-MAY-2022, entry version 108.
DE   RecName: Full=SsrA-binding protein {ECO:0000255|HAMAP-Rule:MF_00023};
DE   AltName: Full=Small protein B {ECO:0000255|HAMAP-Rule:MF_00023};
GN   Name=smpB {ECO:0000255|HAMAP-Rule:MF_00023}; OrderedLocusNames=LL1722;
GN   ORFNames=L160560;
OS   Lactococcus lactis subsp. lactis (strain IL1403) (Streptococcus lactis).
OC   Bacteria; Firmicutes; Bacilli; Lactobacillales; Streptococcaceae;
OC   Lactococcus.
OX   NCBI_TaxID=272623;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=IL1403;
RX   PubMed=11337471; DOI=10.1101/gr.gr-1697r;
RA   Bolotin A., Wincker P., Mauger S., Jaillon O., Malarme K., Weissenbach J.,
RA   Ehrlich S.D., Sorokin A.;
RT   "The complete genome sequence of the lactic acid bacterium Lactococcus
RT   lactis ssp. lactis IL1403.";
RL   Genome Res. 11:731-753(2001).
CC   -!- FUNCTION: Required for rescue of stalled ribosomes mediated by trans-
CC       translation. Binds to transfer-messenger RNA (tmRNA), required for
CC       stable association of tmRNA with ribosomes. tmRNA and SmpB together
CC       mimic tRNA shape, replacing the anticodon stem-loop with SmpB. tmRNA is
CC       encoded by the ssrA gene; the 2 termini fold to resemble tRNA(Ala) and
CC       it encodes a 'tag peptide', a short internal open reading frame. During
CC       trans-translation Ala-aminoacylated tmRNA acts like a tRNA, entering
CC       the A-site of stalled ribosomes, displacing the stalled mRNA. The
CC       ribosome then switches to translate the ORF on the tmRNA; the nascent
CC       peptide is terminated with the 'tag peptide' encoded by the tmRNA and
CC       targeted for degradation. The ribosome is freed to recommence
CC       translation, which seems to be the essential function of trans-
CC       translation. {ECO:0000255|HAMAP-Rule:MF_00023}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000255|HAMAP-Rule:MF_00023}.
CC       Note=The tmRNA-SmpB complex associates with stalled 70S ribosomes.
CC       {ECO:0000255|HAMAP-Rule:MF_00023}.
CC   -!- SIMILARITY: Belongs to the SmpB family. {ECO:0000255|HAMAP-
CC       Rule:MF_00023}.
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DR   EMBL; AE005176; AAK05820.1; -; Genomic_DNA.
DR   PIR; B86840; B86840.
DR   RefSeq; NP_267878.1; NC_002662.1.
DR   RefSeq; WP_003130878.1; NC_002662.1.
DR   AlphaFoldDB; Q9CEW2; -.
DR   SMR; Q9CEW2; -.
DR   STRING; 272623.L160560; -.
DR   PaxDb; Q9CEW2; -.
DR   EnsemblBacteria; AAK05820; AAK05820; L160560.
DR   GeneID; 66442709; -.
DR   KEGG; lla:L160560; -.
DR   PATRIC; fig|272623.7.peg.1847; -.
DR   eggNOG; COG0691; Bacteria.
DR   HOGENOM; CLU_108953_0_1_9; -.
DR   OMA; WTNHSAR; -.
DR   Proteomes; UP000002196; Chromosome.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0003723; F:RNA binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0070929; P:trans-translation; IEA:UniProtKB-UniRule.
DR   CDD; cd09294; SmpB; 1.
DR   Gene3D; 2.40.280.10; -; 1.
DR   HAMAP; MF_00023; SmpB; 1.
DR   InterPro; IPR023620; SmpB.
DR   InterPro; IPR000037; SsrA-bd_prot.
DR   InterPro; IPR020081; SsrA-bd_prot_CS.
DR   PANTHER; PTHR30308; PTHR30308; 1.
DR   Pfam; PF01668; SmpB; 1.
DR   SUPFAM; SSF74982; SSF74982; 1.
DR   TIGRFAMs; TIGR00086; smpB; 1.
DR   PROSITE; PS01317; SSRP; 1.
PE   3: Inferred from homology;
KW   Cytoplasm; Reference proteome; RNA-binding.
FT   CHAIN           1..155
FT                   /note="SsrA-binding protein"
FT                   /id="PRO_0000102965"
SQ   SEQUENCE   155 AA;  17948 MW;  316D6BB762BE1AF8 CRC64;
     MVKNTEDKPL AQNKKARHDY EIYETFEAGI VLTGTEIKSV RQAKIQLKDG FARVRNGEVW
     LSNVHIAPFE QGNIFNVEEL RTRKLLLNKK EIAKIDKELS GTGITFIPLK VYLKNGFAKV
     LMGLARGKKD YDKRETLKRK EQNRDIARQI KAYNR