3a3o
Crystal structure of complex between SA-subtilisin and Tk-propeptide with deletion of the five C-terminal residues
Structural highlights
FunctionTKSU_THEKO Has a broad substrate specificity with a slight preference to large hydrophobic amino acid residues at the P1 position. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTk-subtilisin requires Ca(2+) for folding. This folding is accelerated by the chaperone function of its propeptide (Tkpro). Several Tkpro and Tk-subtilisin derivatives were constructed to examine whether the interactions between the C-terminal extended region of Tkpro and Tk-subtilisin and Glu61/Asp63- and Glu201-mediated hydrogen bonds at the domain interface are important for the chaperone function of Tkpro. The Tkpro derivatives with a series of C-terminal truncations and double mutations at Glu61 and Asp63 exhibited weaker chaperone functions than Tkpro for SA-subtilisin (active-site mutant of Tk-subtilisin). Good correlation was observed between their chaperone functions and binding abilities to the folded SA-subtilisin protein. These results suggest that the C-terminal extended region, Glu61, and Asp63 of Tkpro are not critical for folding of Tk-subtilisin but accelerate it by binding to a folding intermediate of Tk-subtilisin with a native-like structure at their binding sites. In contrast, Tkpro exhibited little chaperone function for E201A/SA-subtilisin. It could bind to the folded E201A/SA-subtilisin protein with a lower association constant than that for SA-subtilisin. These results suggest a loop of Tkpro, which interacts with Glu201 of Tk-subtilisin through hydrogen bonds and is required for folding of Tk-subtilisin by binding to a folding intermediate of Tk-subtilisin with a nonnative structure. Because this loop is fairly hydrophobic and tightly packs to the surface parallel helices of the central alphabetaalpha substructure of Tk-subtilisin, binding of this loop to Glu201 may induce association of these two helices and thereby formation of the alphabetaalpha substructure. We propose that Glu201-mediated interactions are critical for initiation of Tkpro-catalyzed folding of Tk-subtilisin. Identification of the interactions critical for propeptide-catalyzed folding of Tk-subtilisin.,Tanaka S, Matsumura H, Koga Y, Takano K, Kanaya S J Mol Biol. 2009 Nov 27;394(2):306-19. doi: 10.1016/j.jmb.2009.09.028. Epub 2009 , Sep 18. PMID:19766655[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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