Molecular basis for ATPase-powered substrate translocation by the Lon AAA+ protease

J Biol Chem. 2021 Oct;297(4):101239. doi: 10.1016/j.jbc.2021.101239. Epub 2021 Sep 24.


The Lon AAA+ (adenosine triphosphatases associated with diverse cellular activities) protease (LonA) converts ATP-fuelled conformational changes into sufficient mechanical force to drive translocation of a substrate into a hexameric proteolytic chamber. To understand the structural basis for the substrate translocation process, we determined the cryo-electron microscopy (cryo-EM) structure of Meiothermus taiwanensis LonA (MtaLonA) in a substrate-engaged state at 3.6 Å resolution. Our data indicate that substrate interactions are mediated by the dual pore loops of the ATPase domains, organized in spiral staircase arrangement from four consecutive protomers in different ATP-binding and hydrolysis states. However, a closed AAA+ ring is maintained by two disengaged ADP-bound protomers transiting between the lowest and highest position. This structure reveals a processive rotary translocation mechanism mediated by LonA-specific nucleotide-dependent allosteric coordination among the ATPase domains, which is induced by substrate binding.

Keywords: AAA+ protease; ATP hydrolysis; Lon; structure; substrate translocation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / chemistry*
  • Adenosine Triphosphatases / genetics
  • Bacteria / enzymology*
  • Bacteria / genetics
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Crystallography, X-Ray
  • Protease La / chemistry*
  • Protease La / genetics
  • Protein Structure, Secondary


  • Bacterial Proteins
  • Protease La
  • Adenosine Triphosphatases