Iron-sulfur cluster biosynthesis. Molecular chaperone DnaK promotes IscU-bound [2Fe-2S] cluster stability and inhibits cluster transfer activity

Shu-Pao Wu, Sheref S. Mansy, J. A. Cowan*

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

IscU functions as a scaffold for Fe-S cluster assembly and transfer, and is known to be a substrate protein for molecular chaperones. Kinetic studies of Fe-S cluster transfer from holo IscU to apo Fd in the presence of chaperone DnaK demonstrate an inhibitory effect on the rate of Fe-S cluster transfer from IscU. Binding of DnaK reduces the rate of formation of the IscU-Fd complex (greater than 8-fold), but has little influence on the intrinsic rate of iron-sulfur cluster transfer to apo Fd. Apparently the molecular chaperone DnaK does not facilitate the process of Fe-S cluster transfer from IscU. Rather, DnaK has a modest influence on the stability of the IscU-bound Fe-S cluster that may reflect a more important role in promoting cluster assembly. In accord with prior observations the cochaperone DnaJ stimulates the ATPase activity of DnaK, but has a minimal influence on IscU cluster transfer activity, either alone or in concert with DnaK.

Original languageEnglish
Pages (from-to)4284-4293
Number of pages10
JournalBiochemistry
Volume44
Issue number11
DOIs
StatePublished - 22 Mar 2005

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