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Title
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Sequence and structure of Clp P, the proteolytic component of the ATP-dependent Clp protease of Escherichia coli.
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Authors
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M.R.Maurizi,
W.P.Clark,
Y.Katayama,
S.Rudikoff,
J.Pumphrey,
B.Bowers,
S.Gottesman.
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Ref.
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J Biol Chem, 1990,
265,
12536-12545.
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PubMed id
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Abstract
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The ATP-dependent Clp protease of Escherichia coli contains two dissimilar
components: the Clp A regulatory polypeptide, with two ATP binding sites and
intrinsic ATPase activity, and the Clp P subunit, which contains the proteolytic
active site. The DNA sequence of the clpP gene predicts a protein of 207 amino
acids (Mr 21,679), which is in close agreement with the size determined by
sodium dodecyl sulfate-gel electrophoresis of purified Clp P. Clp P has a native
Mr of approximately 240,000, and electron micrographs of the protein show
superimposed disk-like structures with a central cavity, similar in appearance
to purified proteasomes from eukaryotic cells. Clp P is synthesized with a
14-amino acid leader which is rapidly cleaved in vivo to yield the 193-amino
acid protein which has activity in vitro. The clpP gene is at 10 min on the E.
coli map, close to that for the ATP-dependent Lon protease of E. coli and far
from the gene for clpA. Primer extension experiments indicate that transcription
initiates immediately upstream of the coding region for Clp P, with a major
transcription start at 120 bases in front of the start of translation. Insertion
mutations in clpP have been isolated and transferred to the chromosome; strains
devoid of Clp P are viable in the presence or absence of Lon protease. Mutations
in clpP stabilize the same Clp A-beta-galactosidase fusion protein specifically
stabilized by clpA mutations, providing the first genetic evidence that Clp A
and Clp P act together in vivo.
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