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Subunit‐specific degradation of the UmuD/D′ heterodimer by the ClpXP protease: the role of trans recognition in UmuD′ stability
Author(s) -
Gonzalez Martín,
Rasulova Fatima,
Maurizi Michael R.,
Woodgate Roger
Publication year - 2000
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/19.19.5251
Subject(s) - biology , protein subunit , sos response , protease , escherichia coli , proteolysis , biochemistry , biophysics , microbiology and biotechnology , dna , dna damage , enzyme , gene
The Escherichia coli UmuD′ protein is a subunit of the recently described error‐prone DNA polymerase, pol V. UmuD′ is initially synthesized as an unstable and mutagenically inactive pro‐protein, UmuD. Upon processing, UmuD′ assumes a relatively stable conformation and becomes mutagenically active. While UmuD and UmuD′ by themselves exist in vivo as homodimers, when together they preferentially interact to form heterodimers. Quite strikingly, it is in this context that UmuD′ becomes susceptible to ClpXP‐mediated proteolysis. Here we report a novel targeting mechanism designed for degrading the mutagenically active UmuD′ subunit of the UmuD/D′ heterodimer complex, while leaving the UmuD protein intact. Surprisingly, a signal that is essential and sufficient for targeting UmuD′ for degradation was found to reside on UmuD not UmuD′. UmuD was also shown to be capable of channeling an excess of UmuD′ to ClpXP for degradation, thereby providing a mechanism whereby cells can limit error‐prone DNA replication.