Genetic Analysis of Four Sexual Differentiation Process Proteins (isp4/SDPs) in Chaetomium thermophilum and Thermomyces lanuginosus Reveals Their Distinct Roles in Development

Abstract

Fungal sexual development requires the involvement of a large number of functional genes. Fungal genes encoding sexual differentiation process proteins (SDPs), isps, have been known for decades. isp4/SDP and its homologs function as oligopeptide transporters (OPTs), yet their roles in reproduction are unknown. Here, we genetically analyzed all four isp4/SDP homologs in the sexual species Chaetomium thermophilum and asexual species Thermomyces lanuginosus. Using single gene deletion mutants, we found that T. lanuginosus SDP (TlSDP) participated in asexual sporulation, whereas the other homologs participated in sexual morphogenesis. In complementary tests, C. thermophilum SDPs (CtSDP1-3) restored sporulation defects in TlSDP deletion strains (TlSDP), and their translated proteins, which were localized onto the cytomembrane, possessed OPT activity. Interestingly, CtSDP2 accumulated at the top of the hyphae played a distinct role in determining the sexual cycle, glutathione transport, and lifespan shortening. A unique 72nt-insertion fragment (72INS) was discovered in CtSDP2. Biological analysis of the 72INS deletion and DsRED-tagged fusion strains implied the involvement of 72INS in fungal growth and development. In contrast to TlSDP, which only contributes to conidial production, the three CtSDPs play important roles in sexual and asexual reproduction, and CtSDP2 harbors a unique functional 72INS that initiates sexual morphogenesis.

Insights into the cellulose degradation mechanism of the thermophilic fungus Chaetomium thermophilum based on integrated functional omics

“…T. lanuginosus could absorb arabinose well for growth and degrade xylan efficiently but could not utilize cellulose [41,59,60] while C. thermophilum could degrade cellulose well, showing a partial complementary in their ability to degrade lignocellulose. What's more, a study had shown that the thermophilic fungi C. thermophilum and T. lanuginosus coexisted in the same habitats, which had relatively high temperatures and lignocellulose-rich composts [61]. So we suppose that C. thermophilum may be symbiotic with T. lanuginosus, which needs more effort for further study.…”

Responses of the Mushroom Pleurotus ostreatus under Different CO2 Concentration by Comparative Proteomic Analyses

“…As we can see from the results, the expression of the sexual differentiation process protein Isp4 (A0A067N4P4) was significantly down-regulated in the HCO group. Sexual differentiation process proteins have been studied in Schizosaccharomyces pombe and some other fungi [ 31 , 32 ], and isp4 has been found to be up-regulated by nitrogen-starvation-induced meiosis. A0A067N4P4, which might be involved in meiosis and reproduction in P. ostreatus , has 53.0% amino-acid sequence identity with Isp4 in S. pombe (NP_595653).…”

A Homologous Recombination System to Generate Epitope-Tagged Target Genes in Chaetomium thermophilum: A Genetic Approach to Investigate Native Thermostable Proteins

“…Disadvantageous to all of the aforementioned methods is, however, that only ectopic chromosomal integrations without any knowledge of the gene locus, number of integration events or expression levels were possible in the past. Although deletion mutants have already been created in C. thermophilum wild-type mycelia, the procedure appeared to be inefficient and imperfect (e.g., some desired strains were impossible to obtain despite screening thousands of candidate transformants) [ 21 ]. To circumvent these difficulties, we aimed to develop a homologous recombination (HR)-compatible C. thermophilum strain to conceive precise gene modification/replacement experiments, as HR allows efficient incorporation, expression control, and modification of desired target genes, respectively.…”