Crystal structure of archaeal homolog of proteasome-assembly chaperone PbaA

Formation of the eukaryotic proteasome is not a spontaneous process but a highly ordered process assisted by several assembly chaperones. In contrast, archaeal proteasome subunits can spontaneously assemble into an active form. Recent bioinformatic analysis identified the proteasome-assembly chapero...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2014-10, Vol.453 (3), p.493-497
Main Authors: Sikdar, Arunima, Satoh, Tadashi, Kawasaki, Masato, Kato, Koichi
Format: Article
Language:English
Subjects:
Archaeal Proteins - chemistry
Crystallography, X-Ray
Models, Molecular
Molecular Chaperones - chemistry
Proteasome Endopeptidase Complex - chemistry
Protein Conformation
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Summary:Formation of the eukaryotic proteasome is not a spontaneous process but a highly ordered process assisted by several assembly chaperones. In contrast, archaeal proteasome subunits can spontaneously assemble into an active form. Recent bioinformatic analysis identified the proteasome-assembly chaperone-like proteins, PbaA and PbaB, in archaea. Our previous study showed that the PbaB homotetramer functions as a proteasome activator through its tentacle-like C-terminal segments. However, a functional role of the other homolog PbaA has remained elusive. Here we determined the 2.25-Å resolution structure of PbaA, illustrating its disparate tertiary and quaternary structures compared with PbaB. PbaA forms a homopentamer in which the C-terminal segments, with a putative proteasome-activating motif, are packed against the core. These findings offer deeper insights into the molecular evolution relationships between the proteasome-assembly chaperones and the proteasome activators.
ISSN:0006-291X
1090-2104
DOI:10.1016/j.bbrc.2014.09.114