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PDBsum entry 3tb7
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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 analysis of group b streptococcus sortase c1: a model for the "lid" movement upon substrate binding.
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Authors
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B.Khare,
Z.Q.Fu,
I.H.Huang,
H.Ton-That,
S.V.Narayana.
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Ref.
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J Mol Biol, 2011,
414,
563-577.
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PubMed id
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Abstract
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A unique feature of the class-C-type sortases, enzymes essential for
Gram-positive pilus biogenesis, is the presence of a flexible "lid"
anchored in the active site. However, the mechanistic details of the
"lid" displacement, suggested to be a critical prelude for enzyme
catalysis, are not yet known. This is partly due to the absence of
enzyme-substrate and enzyme-inhibitor complex crystal structures. We have
recently described the crystal structures of the Streptococcus agalactiae
SAG2603 V/R sortase SrtC1 in two space groups (type II and type III) and that of
its "lid" mutant and proposed a role of the "lid" as a
protector of the active-site hydrophobic environment. Here, we report the
crystal structures of SAG2603 V/R sortase C1 in a different space group (type I)
and that of its complex with a small-molecule cysteine protease inhibitor. We
observe that the catalytic Cys residue is covalently linked to the
small-molecule inhibitor without lid displacement. However, the type I structure
provides a view of the sortase SrtC1 lid displacement while having structural
elements similar to a substrate sorting motif suitably positioned in the active
site. We propose that these major conformational changes seen in the presence of
a substrate mimic in the active site may represent universal features of class C
sortase substrate recognition and enzyme activation.
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