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Cellular and Molecular Life Sciences CMLS

, Volume 59, Issue 10, pp 1607–1616 | Cite as

Protein folding and degradation in bacteria:¶To degrade or not to degrade? That is the question

  • D. A. Dougan
  • A. Mogk
  • B. Bukau

Abstract.

In Escherichia coli protein quality control is carried out by a protein network, comprising chaperones and proteases. Central to this network are two protein families, the AAA+ and the Hsp70 family. The major Hsp70 chaperone, DnaK, efficiently prevents protein aggregation and supports the refolding of damaged proteins. In a special case, DnaK, together with the assistance of the AAA+ protein ClpB, can also refold aggregated proteins. Other Hsp70 systems have more specialized functions in the cell, for instance HscA appears to be involved in the assembly of Fe/S proteins. In contrast to ClpB, many AAA+ proteins associate with a peptidase to form proteolytic machines which remove irreversibly damaged proteins from the cellular pool. The AAA+ component of these proteolytic machines drives protein degradation. They are required not only for recognition of the substrate but also for substrate unfolding and translocation into the proteolytic chamber. In many cases, specific adaptor proteins modify the substrate binding properties of AAA+ proteins. While chaperones and proteases do not appear to directly cooperate with each other, both systems appear to be necessary for proper functioning of the cell and can, at least in part, substitute for one another.

Key words. Chaperone; protease; folding; degradation; AAA+ superfamily; Hsp70; adaptor proteins. 

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Copyright information

© Birkhäuser Verlag, 2002

Authors and Affiliations

  • D. A. Dougan
    • 1
  • A. Mogk
    • 1
  • B. Bukau
    • 1
  1. 1.Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Str. 7, Freiburg 79104 (Germany), e-mail: bukau@zmbh.uni-heidelberg.deDE

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