The ssrA-Tag Facilitated Degradation of an Integral Membrane Protein

Biochemistry. 2016 Apr 26;55(16):2301-4. doi: 10.1021/acs.biochem.6b00038. Epub 2016 Apr 18.

Abstract

ATP-dependent degradation plays a critical role in the quality control and recycling of proteins in cells. However, complete degradation of membrane proteins by ATP-dependent proteases in bacteria is not well-studied. We discovered that the degradation of a multidomain and multispan integral membrane protein AcrB could be facilitated by the introduction of a ssrA-tag at the C-terminus of the protein sequence and demonstrated that the cytoplasmic unfoldase-protease complex ClpXP was involved in the degradation. This is the first report to our knowledge to reveal that the ClpXP complex is capable of degrading integral membrane proteins. The chaperone SspB also played a role in the degradation. Using purified proteins, we demonstrated that the addition of the ssrA-tag did not drastically affect the structure of AcrB, and the degradation of detergent solubilized AcrB by purified ClpXP could be observed in vitro.

MeSH terms

  • Amino Acid Sequence
  • Endopeptidase Clp / metabolism*
  • Escherichia coli / chemistry
  • Escherichia coli / metabolism*
  • Escherichia coli Infections / microbiology
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / metabolism*
  • Humans
  • Models, Molecular
  • Multidrug Resistance-Associated Proteins / chemistry
  • Multidrug Resistance-Associated Proteins / metabolism*
  • Protein Conformation
  • Proteolysis

Substances

  • AcrB protein, E coli
  • Escherichia coli Proteins
  • Multidrug Resistance-Associated Proteins
  • ClpXP protease, E coli
  • Endopeptidase Clp