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PDBsum entry 4mm3
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Signaling protein/hydrolase
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PDB id
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4mm3
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References listed in PDB file
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Key reference
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Title
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Structural basis for the ubiquitin-Linkage specificity and deisgylating activity of sars-Cov papain-Like protease.
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Authors
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K.Ratia,
A.Kilianski,
Y.M.Baez-Santos,
S.C.Baker,
A.Mesecar.
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Ref.
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Plos Pathog, 2014,
10,
e1004113.
[DOI no: ]
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PubMed id
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Abstract
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Severe acute respiratory syndrome coronavirus (SARS-CoV) encodes a papain-like
protease (PLpro) with both deubiquitinating (DUB) and deISGylating activities
that are proposed to counteract the post-translational modification of signaling
molecules that activate the innate immune response. Here we examine the
structural basis for PLpro's ubiquitin chain and interferon stimulated gene 15
(ISG15) specificity. We present the X-ray crystal structure of PLpro in complex
with ubiquitin-aldehyde and model the interaction of PLpro with other
ubiquitin-chain and ISG15 substrates. We show that PLpro greatly prefers K48- to
K63-linked ubiquitin chains, and ISG15-based substrates to those that are
mono-ubiquitinated. We propose that PLpro's higher affinity for K48-linked
ubiquitin chains and ISG15 stems from a bivalent mechanism of binding, where two
ubiquitin-like domains prefer to bind in the palm domain of PLpro with the most
distal ubiquitin domain interacting with a "ridge" region of the thumb
domain. Mutagenesis of residues within this ridge region revealed that these
mutants retain viral protease activity and the ability to catalyze hydrolysis of
mono-ubiquitin. However, a select number of these mutants have a significantly
reduced ability to hydrolyze the substrate ISG15-AMC, or be inhibited by
K48-linked diubuiquitin. For these latter residues, we found that PLpro
antagonism of the nuclear factor kappa-light-chain-enhancer of activated B-cells
(NFκB) signaling pathway is abrogated. This identification of key and unique
sites in PLpro required for recognition and processing of diubiquitin and ISG15
versus mono-ubiquitin and protease activity provides new insight into
ubiquitin-chain and ISG15 recognition and highlights a role for PLpro DUB and
deISGylase activity in antagonism of the innate immune response.
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