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PDBsum entry 5il9
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References listed in PDB file
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Key reference
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Title
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The crystal structure of deg9 reveals a novel octameric-Type htra protease.
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Authors
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M.Ouyang,
X.Li,
S.Zhao,
H.Pu,
J.Shen,
Z.Adam,
T.Clausen,
L.Zhang.
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Ref.
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Nat Plants, 2017,
3,
973-982.
[DOI no: ]
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PubMed id
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Abstract
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The high temperature requirement A (HtrA) proteases (also termed Deg proteases)
play important roles in diverse organisms by regulating protein quality and
quantity. One of the 16 Arabidopsis homologs, Deg9, is located in the nucleus
where it modulates cytokinin- and light-mediated signalling via degrading the
ARABIDOPSIS RESPONSE REGULATOR 4 (ARR4). To uncover the structural features
underlying the proteolytic activity of Deg9, we determined its crystal
structure. Unlike the well-established trimeric building block of HtrAs, Deg9
displays a novel octameric structure consisting of two tetrameric rings that
have distinct conformations. Based on the structural architecture, we generated
several mutant variants of Deg9, determined their structure and tested their
proteolytic activity towards ARR4. The results of the structural and biochemical
analyses allowed us to propose a model for a novel mechanism of substrate
recognition and activity regulation of Deg9. In this model, protease activation
of one tetramer is mediated by en-bloc reorientation of the protease domains to
open an entrance for the substrate in the opposite (inactive) tetramer. This
study provides the structural basis for understanding how the levels of nuclear
signal components are regulated by a plant protease.
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