Biology subjects

Clave, C.

Publications and source records attributed to Clave, C..

3 recordsLinked to original sources

bioRxiv2023

het-B allorecognition in Podospora anserina is determined by pseudo-allelic interaction of genes encoding a HET and lectin fold domain protein and a PII-like protein

Filamentous fungi display allorecognition genes that trigger regulated cell death (RCD) when strains of unlike genotype fuse. Podospora anserina is one of several model species for the study of this allorecognition process termed heterokaryon or vegetative incompatibility. Incompatibility restricts transmission of mycoviruses between isolates. In P. anserina, genetic analyses have identified nine incompatibility loci, termed het loci. Here we set out to clone the genes controlling het-B incompatibility. het-B displays two incompatible alleles, het-B1 and het-B2. We find that the het-B locus encompasses two adjacent genes, Bh and Bp that exist as highly divergent allelic variants (Bh1/Bh2 and Bp1/Bp2) in the incompatible haplotypes. Bh encodes a protein with an N-terminal HET domain, a cell death inducing domain bearing homology to Toll/interleukin-1 receptor (TIR) domains and a C-terminal domain with a predicted lectin fold. The Bp product is homologous to PII-like proteins, a family of small trimeric proteins acting as sensors of adenine nucleotides in bacteria. We show that although the het-B system appears genetically allelic, incompatibility is in fact determined by the non-allelic Bh1/Bp2 interaction while the reciprocal Bh2/Bp1 interaction plays no role in incompatibility. The highly divergent C-terminal lectin fold domain of BH determines recognition specificity. Population studies and genome analyses indicate that het-B is under balancing selection with trans-species polymorphism, highlighting the evolutionary significance of the two incompatible haplotypes. In addition to emphasizing anew the central role of TIR-like HET domains in fungal RCD, this study identifies novel players in fungal allorecognition and completes the characterization of the entire het gene set in that species. Author summaryMany cellular life forms display genetic systems that protect individuality and discriminate conspecific self from non-self. In filamentous fungi, cell fusion events between strains are under check by specific allorecognition genes that trigger regulated cell death upon detection of non-self. The role of incompatibility is to restrict mycovirus transmission and conspecific parasitism. Podospora anserina, a good model for the study of this form of allorecognition, harbors nine incompatibility het loci. Previous studies have revealed that these genes can be homologous to genes with immune functions in other phyla including bacteria, plants and animals. We have cloned het-B, the last of the nine het genes that remained to be identified and found that it is a complex locus comprising two adjacent genes Bh and Bp. BH displays an N-terminal HET domain (related to TIR domains) and a C-terminal domain with a predicted lectin fold. BP is homologous to PII-like proteins, known bacterial metabolite sensors. Intriguingly, despite apparent genetic allelism, incompatibility is dictated by the non-allelic Bh/Bp interaction. This study stresses the reoccurring involvement of HET domains in fungal RCD and signs completion of the characterization of the entire set of het loci in that species, enabling a comparative analysis of the different genetic architectures underlying allorecognition.

genetics↗

bioRxiv2021

Fungal gasdermin-like proteins are controlled by proteolytic cleavage

Gasdermins are a family of pore-forming proteins controlling an inflammatory cell death reaction in the mammalian immune system. The pore-forming ability of the gasdermin proteins is released by proteolytic cleavage with the removal of their inhibitory C-terminal domain. Recently, gasdermin-like proteins have been discovered in fungi and characterized as cell death-inducing toxins in the context of conspecific non-self discrimination (allorecognition). Although functional analogies have been established between mammalian and fungal gasdermins, the molecular pathways regulating gasdermin activity in fungi remain largely unknown. Here, we characterize a gasdermin-based cell death reaction, controlled by the het-Q allorecognition genes in the filamentous fungus Podospora anserina. We show that the cytotoxic activity of the HET-Q1 gasdermin is controlled by proteolysis. HET-Q1 loses a [~]5 kDa C-terminal fragment during the cell death reaction in presence of a subtilisin-like serine protease, termed HET-Q2. Mutational analyses and successful reconstitution of the cell death reaction in a heterologous host (Saccharomyces cerevisiae) suggest that HET-Q2 directly cleaves HET-Q1 to induce cell death. By analysing the genomic landscape of het-Q1 homologs in fungi, we uncovered that the vast majority of the gasdermin genes are clustered with protease-encoding genes. These HET-Q2-like proteins carry either subtilisin-like or caspase-related proteases, which in some cases correspond to the N-terminal effector domain of NOD-like receptor proteins (NLRs). This study thus reveals the proteolytic regulation of gasdermins in fungi and establishes evolutionary parallels between fungal and mammalian gasdermin-dependent cell death pathways. SignificanceThe recent discovery of gasdermin-like proteins in fungi have brought to light that this family of pore-forming proteins controls cell death in two of the major eukaryotic kingdoms, fungi and mammals. Yet, the regulation of cytotoxicity of the fungal gasdermins and their molecular pathways remain uncharacterized. Here, we describe the regulation through proteolytic cleavage of the fungal gasdermin HET-Q1 and uncover that majority of fungal gasdermins are genomically clustered with protease-encoding genes. Some of these genes encode proteins with caspase-related domains and/or are members of a family of immune receptors in mammals and plants. Overall, this work contributes towards our understanding of the evolution of gasdermin-dependent cell death, enlightening multiple evolutionary parallels between signaling pathways in mammals and fungi.

genetics↗

bioRxiv2019

Combinations of Spok genes create multiple meiotic drivers in Podospora

Meiotic drive is the preferential transmission of a particular allele at a given locus during sexual reproduction. The phenomenon is observed as spore killing in a variety of fungal lineages, including Podospora. In natural populations of Podospora anserina, seven spore killers (Psks) have been identified through classical genetic analyses. Here we show that the Spok gene family underlie the Psk spore killers. The combination of the various Spok genes at different chromosomal locations defines the spore killers and creates a killing hierarchy within the same population. We identify two novel Spok homologs that are located within a complex region (the Spok block) that reside in different chromosomal locations in given natural strains. We confirm that the individual SPOK proteins perform both the killing and resistance functions and show that these activities are dependent on distinct domains, a nuclease and a kinase domain respectively. Genomic data and phylogenetic analysis across ascomycetes suggest that the Spok genes disperse via cross-species transfer, and evolve by duplication and diversification within several lineages.

genetics↗