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PDBsum entry 2as9
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References listed in PDB file
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Key reference
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Title
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Functional and structural characterization of spl proteases from staphylococcus aureus.
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Authors
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G.M.Popowicz,
G.Dubin,
J.Stec-Niemczyk,
A.Czarny,
A.Dubin,
J.Potempa,
T.A.Holak.
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Ref.
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J Mol Biol, 2006,
358,
270-279.
[DOI no: ]
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PubMed id
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Abstract
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Staphylococcus aureus is the major cause of nosocomial infections world-wide,
with increasing prevalence of community-acquired diseases. The recent dramatic
increase in multi-antibiotic resistance, including resistance to the last-resort
drug, vancomycin, together with the lack of an effective vaccine highlight the
need for better understanding of S.aureus pathogenicity. Comparative analysis of
available bacterial genomes allows for the identification of previously
uncharacterized S.aureus genes with potential roles in pathogenicity. A good
example is a cluster of six serine protease-like (spl) genes encompassed in one
operon, which encode for putative proteases with similarity to staphylococcal
glutamylendopeptidase (V8 protease). Here, we describe an efficient expression
system for the production of recombinant SplB and SplC proteases in Escherichia
coli, together with structural and functional characterization of the purified
enzymes. A unique mechanism of cytoplasm protection against activity of
misdirected SplB was uncovered. Apparently, the co-translated signal peptide
maintains protease latency until it is cleaved by the signal peptidase during
protein secretion. Furthermore, the crystal structure of the SplC protease
revealed a fold resembling that of the V8 protease and epidermolytic toxins.
Arrangement of the active site cleft and substrate-binding pocket of SplC
explains the mechanism of enzyme latency and suggests that some Spl proteases
possess restricted substrate specificity similar to that of the V8 protease and
epidermolytic toxins.
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Figure 2.
Figure 2. Surface representation of the SplC molecule. The
catalytic triad (yellow) is blocked by Gly175–Gly176 and the
whole Tyr174–Tyr184 loop region interferes with enzymatic
activity. The specificity region built by Val119, Phe149, Ile153
and Val173 enables binding of a medium-sized hydrophobic residue.
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Figure 4.
Figure 4. Structure of SplC (red) superimposed on the V8
protease (blue). (a) An overall view of the whole model showing
a high degree of structural similarity. (b) The detailed view of
the active site and specificity region. The structures appear to
be almost identical, except for the Tyr174–Tyr184 loop, which
is β-structured in V8 while flexible in SplC. The “locked”
state of the catalytic His40 is evident.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
358,
270-279)
copyright 2006.
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