Flexible linkers leash the substrate binding domain of SspB to a peptide module that stabilizes delivery complexes with the AAA+ ClpXP protease

Mol Cell. 2003 Aug;12(2):355-63. doi: 10.1016/s1097-2765(03)00272-7.

Abstract

SspB dimers bind proteins bearing the ssrA-degradation tag and stimulate their degradation by the ClpXP protease. Here, E. coli SspB is shown to contain a dimeric substrate binding domain of 110-120 N-terminal residues, which binds ssrA-tagged substrates but does not stimulate their degradation. The C-terminal 40-50 residues of SspB are unstructured but are required for SspB to form substrate-delivery complexes with ClpXP. A synthetic peptide containing the 10 C-terminal residues of SspB binds ClpX, stimulates its ATPase activity, and prevents SspB-mediated delivery of GFP-ssrA for ClpXP degradation. This tripartite structure--an ssrA-tag binding and dimerization domain, a flexible linker, and a short peptide module that docks with ClpX--allows SspB to deliver tagged substrates to ClpXP without interfering with their denaturation or degradation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATPases Associated with Diverse Cellular Activities
  • Adenosine Triphosphatases / chemistry*
  • Adenosine Triphosphate / metabolism
  • Adhesins, Bacterial / chemistry*
  • Adhesins, Bacterial / metabolism
  • Amino Acid Sequence
  • Bacterial Proteins / physiology
  • Binding Sites
  • Dimerization
  • Dose-Response Relationship, Drug
  • Endopeptidase Clp
  • Escherichia coli / metabolism
  • Escherichia coli Proteins*
  • Green Fluorescent Proteins
  • Hydrolysis
  • Luminescent Proteins / metabolism
  • Models, Biological
  • Molecular Chaperones
  • Molecular Sequence Data
  • Mutation
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA, Bacterial / metabolism
  • Sequence Homology, Amino Acid
  • Serine Endopeptidases / chemistry*
  • Substrate Specificity

Substances

  • Adhesins, Bacterial
  • Bacterial Proteins
  • Escherichia coli Proteins
  • Luminescent Proteins
  • Molecular Chaperones
  • RNA, Bacterial
  • tmRNA
  • salivary agglutinin receptor, Streptocococcus
  • Green Fluorescent Proteins
  • Adenosine Triphosphate
  • Serine Endopeptidases
  • ClpXP protease, E coli
  • Endopeptidase Clp
  • Adenosine Triphosphatases
  • ClpX protein, E coli
  • ATPases Associated with Diverse Cellular Activities