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PDBsum entry 5vso
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References listed in PDB file
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Key reference
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Title
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Broadening the functionality of a j-Protein/hsp70 molecular chaperone system.
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Authors
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B.A.Schilke,
S.J.Ciesielski,
T.Ziegelhoffer,
E.Kamiya,
M.Tonelli,
W.Lee,
G.Cornilescu,
J.K.Hines,
J.L.Markley,
E.A.Craig.
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Ref.
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PLoS Genet, 2017,
13,
e1007084.
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PubMed id
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Abstract
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By binding to a multitude of polypeptide substrates, Hsp70-based molecular
chaperone systems perform a range of cellular functions. All J-protein
co-chaperones play the essential role, via action of their J-domains, of
stimulating the ATPase activity of Hsp70, thereby stabilizing its interaction
with substrate. In addition, J-proteins drive the functional diversity of Hsp70
chaperone systems through action of regions outside their J-domains. Targeting
to specific locations within a cellular compartment and binding of specific
substrates for delivery to Hsp70 have been identified as modes of J-protein
specialization. To better understand J-protein specialization, we concentrated
on Saccharomyces cerevisiae SIS1, which encodes an essential J-protein of the
cytosol/nucleus. We selected suppressors that allowed cells lacking SIS1 to form
colonies. Substitutions changing single residues in Ydj1, a J-protein, which,
like Sis1, partners with Hsp70 Ssa1, were isolated. These gain-of-function
substitutions were located at the end of the J-domain, suggesting that
suppression was connected to interaction with its partner Hsp70, rather than
substrate binding or subcellular localization. Reasoning that, if YDJ1
suppressors affect Ssa1 function, substitutions in Hsp70 itself might also be
able to overcome the cellular requirement for Sis1, we carried out a selection
for SSA1 suppressor mutations. Suppressing substitutions were isolated that
altered sites in Ssa1 affecting the cycle of substrate interaction. Together,
our results point to a third, additional means by which J-proteins can drive
Hsp70's ability to function in a wide range of cellular processes-modulating the
Hsp70-substrate interaction cycle.
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