title: ClpXP degrades SsrA-tagged proteins in Streptococcus pneumoniae.
abstract: Bacterial proteins that are abnormally truncated due to incomplete mRNA or the presence of rare codons are extended by an SsrA tag during ribosome rescue in a trans-translation process important for maintaining protein quality. In Escherichia coli, the SsrA-tagged proteins become the target of the Tsp, Lon, FtsH, ClpXP, and ClpAP proteases. Here we show that degradation of model SsrA-tagged proteins in Streptococcus pneumoniae depends primarily or exclusively on ClpXP in vivo. In addition, we show the E. coli SsrA tag is also a target of S. pneumoniae ClpXP in vivo, even though the N-terminal portions of the tags differ significantly between the two species, suggesting there may be no adaptor protein for SsrA in S. pneumoniae.
authors.affiliation: LMB Room 4150, 900 South Ashland Ave., Chicago, IL 60607, USA.
authors.forename: Sarita
authors.initials: S
authors.lastname: Ahlawat
authors.forename: Donald A
authors.initials: DA
authors.lastname: Morrison
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D023061:Gene Order; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013296:Streptococcus pneumoniae / Q000201:enzymology* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; C096222:tmRNA; D010447:Peptide Hydrolases; C483573:ClpXP protease, E coli; D049071:Endopeptidase Clp