Dataset Information

YPXL/I is a protein interaction motif recognized by aspergillus PalA and its human homologue, AIP1/Alix.

ABSTRACT: The zinc finger transcription factor PacC undergoes two-step proteolytic activation in response to alkaline ambient pH. PalA is a component of the fungal ambient pH signal transduction pathway. Its mammalian homologue AIP1/Alix interacts with the apoptosis-linked protein ALG-2. We show that both PalA and AIP1/Alix recognize a protein-protein binding motif that we denote YPXL/I, where Tyr, Pro, and Leu/Ile are crucial for its interactive properties. Two such motifs flanking the signaling protease cleavage site mediate direct binding of PalA to PacC, required for the first and only pH-regulated cleavage of this transcription factor. PalA can bind the "closed" (i.e., wild-type full-length) conformer of PacC, suggesting that PalA binding constitutes the first stage in the two-step proteolytic cascade, recruiting or facilitating access of the signaling protease, presumably PalB. In addition to recognizing YPXL/I motifs, both PalA and AIP1/Alix interact with the Aspergillus class E Vps protein Vps32 homologue, a member of a protein complex involved in the early steps of the multivesicular body pathway, suggesting that this interaction is an additional feature of proteins of the PalA/AIP1/Alix family.

SUBMITTER: Vincent O

PROVIDER: S-EPMC151718 | biostudies-literature | 2003 Mar

REPOSITORIES: biostudies-literature

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YPXL/I is a protein interaction motif recognized by aspergillus PalA and its human homologue, AIP1/Alix.

Vincent Olivier O Rainbow Lynne L Tilburn Joan J Arst Herbert N HN Peñalva Miguel A MA

Molecular and cellular biology 20030301 5

The zinc finger transcription factor PacC undergoes two-step proteolytic activation in response to alkaline ambient pH. PalA is a component of the fungal ambient pH signal transduction pathway. Its mammalian homologue AIP1/Alix interacts with the apoptosis-linked protein ALG-2. We show that both PalA and AIP1/Alix recognize a protein-protein binding motif that we denote YPXL/I, where Tyr, Pro, and Leu/Ile are crucial for its interactive properties. Two such motifs flanking the signaling protease ...[more]

PMID: 12588984

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Project description:Fungal pathogens kill more people per year globally than malaria or tuberculosis and threaten international food security through crop destruction. New sophisticated strategies to inhibit fungal growth are thus urgently needed. Among the potential candidate molecules that strongly inhibit fungal spore germination are small cationic, cysteine-stabilized proteins of the AFP family secreted by a group of filamentous Ascomycetes. Its founding member, AFP from Aspergillus giganteus, is of particular interest since it selectively inhibits the growth of filamentous fungi without affecting the viability of mammalian, plant, or bacterial cells. AFPs are also characterized by their high efficacy and stability. Thus, AFP can serve as a lead compound for the development of novel antifungals. Notably, all members of the AFP family comprise a ?-core motif which is conserved in all antimicrobial proteins from pro- and eukaryotes and known to interfere with the integrity of cytoplasmic plasma membranes. In this study, we used classical molecular dynamics simulations combined with wet laboratory experiments and nuclear magnetic resonance (NMR) spectroscopy to characterize the structure and dynamical behavior of AFP isomers in solution and their interaction with fungal model membranes. We demonstrate that the ?-core motif of structurally conserved AFP is the key for its membrane interaction, thus verifying for the first time that the conserved ?-core motif of antimicrobial proteins is directly involved in protein-membrane interactions. Furthermore, molecular dynamic simulations suggested that AFP does not destroy the fungal membrane by pore formation but covers its surface in a well-defined manner, using a multistep mechanism to destroy the membranes integrity.IMPORTANCE Fungal pathogens pose a serious danger to human welfare since they kill more people per year than malaria or tuberculosis and are responsible for crop losses worldwide. The treatment of fungal infections is becoming more complicated as fungi develop resistances against commonly used fungicides. Therefore, discovery and development of novel antifungal agents are of utmost importance.

Project description:Sendai virus (SeV), belonging to the Respirovirus genus of the family Paramyxoviridae, harbors an accessory protein, named C protein, which facilitates viral pathogenicity in mice. In addition, the C protein is known to stimulate the budding of virus-like particles by binding to the host ALG-2 interacting protein X (Alix), a component of the endosomal sorting complexes required for transport (ESCRT) machinery. However, small interfering RNA (siRNA)-mediated gene knockdown studies suggested that neither Alix nor C protein is related to SeV budding. In the present study, we determined the crystal structure of a complex comprising the C-terminal half of the C protein (Y3) and the Bro1 domain of Alix at a resolution of 2.2 Å to investigate the role of the complex in SeV budding. The structure revealed that a novel consensus sequence, LXXW, which is conserved among Respirovirus C proteins, is important for Alix binding. SeV possessing a mutated C protein with reduced Alix-binding affinity showed impaired virus production, which correlated with the binding affinity. Infectivity analysis showed a 160-fold reduction at 12 h postinfection compared with nonmutated virus, while C protein competes with CHMP4, one subunit of the ESCRT-III complex, for binding to Alix. All together, these results highlight the critical role of C protein in SeV budding. IMPORTANCE Human parainfluenza virus type I (hPIV1) is a respiratory pathogen affecting young children, immunocompromised patients, and the elderly, with no available vaccines or antiviral drugs. Sendai virus (SeV), a murine counterpart of hPIV1, has been studied extensively to determine the molecular and biological properties of hPIV1. These viruses possess a multifunctional accessory protein, C protein, which is essential for stimulating viral reproduction, but its role in budding remains controversial. In the present study, the crystal structure of the C-terminal half of the SeV C protein associated with the Bro1 domain of Alix, a component of cell membrane modulating machinery ESCRT, was elucidated. Based on the structure, we designed mutant C proteins with different binding affinities to Alix and showed that the interaction between C and Alix is vital for viral budding. These findings provide new insights into the development of new antiviral drugs against hPIV1.

Dataset Information

YPXL/I is a protein interaction motif recognized by aspergillus PalA and its human homologue, AIP1/Alix.

Publications

YPXL/I is a protein interaction motif recognized by aspergillus PalA and its human homologue, AIP1/Alix.

Similar Datasets

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