Isolation and characterization of a gene coding for chitin deacetylase specifically expressed during fruiting body development in the basidiomyceteFlammulina velutipesand its expression in the yeastPichia pastoris

Fruiting bodies of mushroom-forming fungi (Agaricomycetes) are among the most complex structures produced by fungi. Unlike vegetative hyphae, fruiting bodies grow determinately and follow a genetically encoded developmental program that orchestrates tissue differentiation, growth and sexual sporulation. In spite of more than a century of research, our understanding of the molecular details of fruiting body morphogenesis is limited and a general synthesis on the genetics of this complex process is lacking. In this paper, we aim to comprehensively identify conserved genes related to fruiting body morphogenesis and distill novel functional hypotheses for functionally poorly characterized genes. As a result of this analysis, we report 921 conserved developmentally expressed gene families, only a few dozens of which have previously been reported in fruiting body development. Based on literature data, conserved expression patterns and functional annotations, we provide informed hypotheses on the potential role of these gene families in fruiting body development, yielding the most complete description of molecular processes in fruiting body morphogenesis to date. We discuss genes related to the initiation of fruiting, differentiation, growth, cell surface and cell wall, defense, transcriptional regulation as well as signal transduction. Based on these data we derive a general model of fruiting body development, which includes an early, proliferative phase that is mostly concerned with laying out the mushroom body plan (via cell division and differentiation), and a second phase of growth via cell expansion as well as meiotic events and sporulation. Altogether, our discussions cover 1480 genes of Coprinopsis cinerea, and their orthologs in Agaricus bisporus, Cyclocybe aegerita, Armillaria ostoyae, Auriculariopsis ampla, Laccaria bicolor, Lentinula edodes, Lentinus tigrinus, Mycena kentingensis, Phanerochaete chrysosporium, Pleurotus ostreatus, and Schizophyllum commune, providing functional hypotheses for ~10% of genes in the genomes of these species. Although experimental evidence for the role of these genes will need to be established in the future, our data provide a roadmap for guiding functional analyses of fruiting related genes in the Agaricomycetes. We anticipate that the gene compendium presented here, combined with developments in functional genomics approaches will contribute to uncovering the genetic bases of one of the most spectacular multicellular developmental processes in fungi. Key words: functional annotation; comparative genomics; cell wall remodeling; development; fruiting body morphogenesis; mushroom; transcriptome

Download Full-text

Isolation and Characterization of the Gene Coding for the Amidinotransferase Involved in the Biosynthesis of Phaseolotoxin in Pseudomonas syringae pv. phaseolicola

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2001.14.4.545 ◽

2001 ◽

Vol 14 (4) ◽

pp. 545-554 ◽

Cited By ~ 37

Author(s):

Gustavo Hernández-Guzmán ◽

Ariel Alvarez-Morales

Keyword(s):

Aspartic Acid ◽

Pseudomonas Syringae ◽

Sequence Similarity ◽

Insertion Mutant ◽

Halo Blight ◽

Streptomyces Spp ◽

Isolation And Characterization ◽

Gene Coding ◽

Blight Disease

Pseudomonas syringae pv. phaseolicola is the causal agent of the “halo blight” disease of beans. A key component in the development of the disease is a nonhost-specific toxin, Nδ-(N'-sulphodiaminophosphinyl)-ornithyl-alanyl-homoarginine, known as phaseolotoxin. The homoarginine residue in this molecule has been suggested to be the product of Larginine:lysine amidinotransferase activity, previously detected in extracts of P. syringae pv. phaseolicola grown under conditions of phaseolotoxin production. We report the isolation and characterization of an amidinotransferase gene (amtA) from P. syringae pv. phaseolicola coding for a polypeptide of 362 residues (41.36 kDa) and showing approximately 40% sequence similarity to Larginine:inosamine-phosphate amidinotransferase from three species of Streptomyces spp. and 50.4% with an Larginine:glycine amidinotransferase from human mitochondria. The cysteine, histidine, and aspartic acid residues involved in substrate binding are conserved. Furthermore, expression of the amtA and argK genes and phaseolotoxin production occurs at 18°C but not at 28°C. An amidinotransferase insertion mutant was obtained that lost the capacity to synthesize homoarginine and phaseolotoxin. These results show that the amtA gene isolated is responsible for the amidinotransferase activity detected previously and that phaseolotoxin production depends upon the activity of this gene.

Download Full-text