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PDBsum entry 1rjx
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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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Characterization of lys-698-To-Met substitution in human plasminogen catalytic domain.
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Authors
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S.Terzyan,
N.Wakeham,
P.Zhai,
K.Rodgers,
X.C.Zhang.
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Ref.
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Proteins, 2004,
56,
277-284.
[DOI no: ]
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PubMed id
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Abstract
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Streptokinase (SK) is a human plasminogen (Pg) activator secreted by
streptococci. The activation mechanism of SK differs from that of physiological
Pg activators in that SK is not a protease and cannot proteolytically activate
Pg. Instead, it forms a tight complex with Pg that proteolytically activates
other Pg molecules. The residue Lys-698 of human Pg was hypothesized to
participate in triggering activation in the SK-Pg complex. Here, we report a
study of the Lys-698 to Met substitution in the catalytic domain of Pg (microPg)
containing the proteolytic activation-resistant background (R561A). While it
remains competent in forming a complex with SK, maintaining a comparable
equilibration dissociation constant (K(D)), the recombinant protein shows a
nearly 60-fold reduction in amidolytic activity relative to its R561A background
when mixed with native SK. A 2.3 A crystal structure of this mutant microPg
confirmed the correct folding of this recombinant protein. Combined with other
biochemical data, these results support the premise that Lys-698 of human Pg
plays a functional role in the so-called N-terminal insertion activation
mechanism by SK.
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Figure 1.
Figure 1. Structural comparison of K698M mutant to other  Pg
( Pm)
crystal structures. In the middle, a ribbon diagram of K698M
structure is shown in stereo view, flanked by diagrams of
comparisons of local backbone traces. Fourteen previously
published Pg
( Pm)
crystal structures from six crystal forms are superimposed onto
the K698M structure by overlaying their C[  ]atoms
(using a 3-Å cutoff). The K698M structure (PDB file 1RJX)
is colored in blue, Pm
structures (1BML and 1BUI) in yellow, free Pg
(1DDJ and 1QRZ) in green, and other Pg
(1L4D and 1L4Z) in magenta. In the stereo diagram, positions of
the K698M mutation and the catalytic Ser-741(195) are marked
with yellow and green spheres, respectively.
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The above figure is
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2004,
56,
277-284)
copyright 2004.
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