The Combinatorial PP1-Binding Consensus Motif (R/K)x (0,1)V/IxFxx(R/K)x(R/K) Is a New Apoptotic Signature

Abstract

BackgroundPrevious studies established that PP1 is a target for Bcl-2 proteins and an important regulator of apoptosis. The two distinct functional PP1 consensus docking motifs, R/Kx(0,1)V/IxF and FxxR/KxR/K, involved in PP1 binding and cell death were previously characterized in the BH1 and BH3 domains of some Bcl-2 proteins.Principal FindingsIn this study, we demonstrate that DPT-AIF1, a peptide containing the AIF562–571 sequence located in a c-terminal domain of AIF, is a new PP1 interacting and cell penetrating molecule. We also showed that DPT-AIF1 provoked apoptosis in several human cell lines. Furthermore, DPT-APAF1 a bi-partite cell penetrating peptide containing APAF-1122–131, a non penetrating sequence from APAF-1 protein, linked to our previously described DPT-sh1 peptide shuttle, is also a PP1-interacting death molecule. Both AIF562–571 and APAF-1122–131 sequences contain a common R/Kx(0,1)V/IxFxxR/KxR/K motif, shared by several proteins involved in control of cell survival pathways. This motif combines the two distinct PP1c consensus docking motifs initially identified in some Bcl-2 proteins. Interestingly DPT-AIF2 and DPT-APAF2 that carry a F to A mutation within this combinatorial motif, no longer exhibited any PP1c binding or apoptotic effects. Moreover the F to A mutation in DPT-AIF2 also suppressed cell penetration.ConclusionThese results indicate that the combinatorial PP1c docking motif R/Kx(0,1)V/IxFxxR/KxR/K, deduced from AIF562–571 and APAF-1122–131 sequences, is a new PP1c-dependent Apoptotic Signature. This motif is also a new tool for drug design that could be used to characterize potential anti-tumour molecules.

Protein phosphatase 1 is a key player in nuclear events

“…The PP1c residues comprising the binding RVxF motif are conserved in all isoforms [16,17]. Several definitions for the RVxF motif has been proposed: [23,24], respectively.…”

TCTEX1D4 Interactome in Human Testis: Unraveling the Function of Dynein Light Chain in Spermatozoa

“…More than half the interactors present a PPP1BM, which may indicate a putative formation of trimers. In fact, a PPP1BM was also identified in TCTEX1D2, which is usually present in apoptotic proteins, such Bcl-2 and Bad, and confers an apoptotic signature (Godet et al, 2010).…”

Serine/threonine protein phosphatases in DNA damage response

“…PP1 has been reported to interact with various subunits through its N terminus. Sequence analysis of all the interacting partners has revealed that most of these proteins contain a consensus PP1-binding motif: (R/K)×1(V/I)×2(F/W), where ×1 may be absent or any residue apart from the large hydrophobic residues, and ×2 denotes any amino acid except large hydrophobic residues, phosphoserine and probably aspartic acid [49,50]. More than 180 conserved mammalian proteins have been identified as potential binding partners of PP1.…”