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Figure 5.
Fig. 5. The structural basis of AvrPphB substrate
specificity. (A) Sequence comparison of AvrPphB cleavage sites
in its precursor and substrate PBS1 protein. A common
Gly-Asp-Lys motif preceding the cleavage sites is highlighted in
red, and the arrow indicates the cleavage sites. (B and C)
Active site clefts of papain-like enzyme and AvrPphB.
Orientation is the same as in Fig. 4A. B shows the molecular
surface of cruzain (PDB ID code 2aim [PDB]
), and C shows that of AvrPphB. The structure of cruzain was
determined with the inhibitor benzoyl-Arg-Ala-fluoromethyl
ketone, which occupies the S3, S2, and S1 sites and is shown in
B Left as a CPK representation. C Right is a zoom-in view of the
proposed active site of AvrPphB. The proposed S2 site residue
(Arg-205) and four catalytically important residues are drawn
underneath the molecular surface. Note the positive character of
S2 and shallowness of S3 at the substrate-binding site. All
surfaces are colored based on the electrostatic potential of the
molecule (ranging from -23 to +23 kT). Images were prepared with
the program GRASP (53).
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