The axial channel of the proteasome core particle is gated by the Rpt2 ATPase and controls both substrate entry and product release.
Substrates enter the proteasome core particle (CP) through a channel that opens upon association with the regulatory particle (RP). Using yeast mutants, we show that channel opening is mediated by the ATPase domain of Rpt2, one of six ATPases in the RP. To test whether degradation products exit through this channel, we analyzed their size distribution. Their median length from an open-channel CP mutant was 40% greater than that from the wild-type. Thus, channel opening may enhance the yield of peptides long enough to function in antigen presentation. These experiments demonstrate that gating of the RP channel controls both substrate entry and product release, and is specifically regulated by an ATPase in the base of the RP.
Köhler
A
A
Department of Cell Biology, Harvard Medical School, 02115, Boston, MA, USA.
Cascio
P
P
Leggett
D S
DS
Woo
K M
KM
Goldberg
A L
AL
Finley
D
D
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D017951:Antigen Presentation / Q000502:physiology; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D015221:Potassium Channels / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D020836:Protein Structure, Quaternary; D013379:Substrate Specificity; D015003:Yeasts
D005656:Fungal Proteins; D009097:Multienzyme Complexes; D015221:Potassium Channels; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000251:Adenosine Triphosphatases