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PDBsum entry 1m4y
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Isolation and characterization of the prokaryotic proteasome homolog hslvu (clpqy) from thermotoga maritima and the crystal structure of hslv.
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Authors
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H.K.Song,
M.Bochtler,
M.K.Azim,
C.Hartmann,
R.Huber,
R.Ramachandran.
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Ref.
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Biophys Chem, 2003,
100,
437-452.
[DOI no: ]
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PubMed id
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Abstract
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Heat-shock locus VU (HslVU) is an ATP-dependent proteolytic system and a
prokaryotic homolog of the proteasome. It consists of HslV, the protease, and
HslU, the ATPase and chaperone. We have cloned, sequenced and expressed both
protein components from the hyperthermophile Thermotoga maritima. T. maritima
HslU hydrolyzes a variety of nucleotides in a temperature-dependent manner, with
the optimum lying between 75 and 80 degrees C. It is also nucleotide-unspecific
for activation of HslV against amidolytic and caseinolytic activity. The
Escherichia coli and T. maritima HslU proteins mutually stimulate HslV proteins
from both sources, suggesting a conserved activation mechanism. The crystal
structure of T. maritima HslV was determined and refined to 2.1-A resolution.
The structure of the dodecameric enzyme is well conserved compared to those from
E. coli and Haemophilus influenzae. A comparison of known HslV structures
confirms the presence of a cation-binding site, although its exact role in the
proteolytic mechanism of HslV remains unclear. Amongst factors responsible for
the thermostability of T. maritima HslV, extensive ionic
interactions/salt-bridge networks, which occur specifically in the T. maritima
enzyme in comparison to its mesophilic counterparts, seem to play an important
role.
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