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Title
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Proteome-wide substrate analysis indicates substrate exclusion as a mechanism to generate caspase-7 versus caspase-3 specificity
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Author
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Abstract
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| Caspase-3 and -7 are considered functionally redundant proteases with similar proteolytic specificities. We performed a proteome-wide screen on a mouse macrophage lysate using the N-terminal combined fractional diagonal chromatography technology and identified 46 shared, three caspase-3-specific, and six caspase-7-specific cleavage sites. Further analysis of these cleavage sites and substitution mutation experiments revealed that for certain cleavage sites a lysine at the P5 position contributes to the discrimination between caspase-7 and -3 specificity. One of the caspase-7-specific substrates, the 40 S ribosomal protein S18, was studied in detail. The RPS18-derived P6-P5' undecapeptide retained complete specificity for caspase-7. The corresponding P6-P1 hexapeptide still displayed caspase-7 preference but lost strict specificity, suggesting that P' residues are additionally required for caspase-7-specific cleavage. Analysis of truncated peptide mutants revealed that in the case of RPS18 the P4-P1 residues constitute the core cleavage site but that P6, P5, P2', and P3' residues critically contribute to caspase-7 specificity. Interestingly, specific cleavage by caspase-7 relies on excluding recognition by caspase-3 and not on increasing binding for caspase-7. Molecular & Cellular Proteomics 8:2700-2714, 2009. |
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Language
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English
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Source (journal)
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Molecular and cellular proteomics. - Birmingham, Ala
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Publication
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Birmingham, Ala
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2009
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ISSN
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1535-9476
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DOI
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10.1074/MCP.M900310-MCP200
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Volume/pages
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8
:12
(2009)
, p. 2700-2714
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ISI
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000272711800008
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Full text (Publisher's DOI)
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