Selective contribution of eukaryotic prefoldin subunits to actin and tubulin binding.
Eukaryotic prefoldin (PFD) is a heterohexameric chaperone with a jellyfish-like structure whose function is to deliver nonnative target proteins, principally actins and tubulins, to the eukaryotic cytosolic chaperonin for facilitated folding. Here we demonstrate that functional PFD can spontaneously assemble from its six constituent individual subunits (PFD1-PFD6), each expressed as a recombinant protein. Using engineered forms of PFD assembled in vitro, we show that the tips of the PFD tentacles are required to form binary complexes with authentic target proteins. We show that PFD uses the distal ends of different but overlapping sets of subunits to form stable binary complexes with different target proteins, namely actin and alpha- and beta-tubulin. We also present data that suggest a model for the order of these six subunits within the hexamer. Our data are consistent with the hypothesis that PFD, like the eukaryotic cytosolic chaperonin, has co-evolved specifically to facilitate the folding of its target proteins.
Simons
C Torrey
CT
Department of Biochemistry, New York University Medical Center, New York, New York 10016, USA.
Staes
An
A
Rommelaere
Heidi
H
Ampe
Christophe
C
Lewis
Sally A
SA
Cowan
Nicholas J
NJ
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
D000199:Actins; D018832:Molecular Chaperones; D021122:Protein Subunits; D011994:Recombinant Proteins; D014404:Tubulin; C112806:prefoldin