Wood is a major pool of organic carbon that is highly resistant to decay, owing largely to the presence of lignin. The only organisms capable of substantial lignin decay are white rot fungi in the Agaricomycetes, which also contains non-lignin-degrading brown rot and ectomycorrhizal species. Comparative analyses of 31 fungal genomes (12 generated for this study) suggest that lignin-degrading peroxidases expanded in the lineage leading to the ancestor of the Agaricomycetes, which is reconstructed as a white rot species, and then contracted in parallel lineages leading to brown rot and mycorrhizal species. Molecular clock analyses suggest that the origin of lignin degradation might have coincided with the sharp decrease in the rate of organic carbon burial around the end of the Carboniferous period.

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The paleozoic origin of enzymatic lignin decomposition reconstructed from 31 fungal genomes

The present review offers an overview of nonclassical (e.g., with no pre- or in situ activation of a carboxylic acid partner) approaches for the construction of amide bonds. The review aims to comprehensively discuss relevant work, which was mainly done in the field in the last 20 years. Organization of the data follows a subdivision according to substrate classes: catalytic direct formation of amides from carboxylic and amines (section 2); the use of carboxylic acid surrogates (section 3); and the use of amine surrogates (section 4). The ligation strategies (NCL, Staudinger, KAHA, KATs, etc.) that could involve both carboxylic acid and amine surrogates are treated separately in section 5.

Nonclassical Routes for Amide Bond Formation

Various compatible solutes enable plants to tolerate abiotic stress, and glycinebetaine (GB) is one of the most-studied among such solutes. Early research on GB focused on the maintenance of cellular osmotic potential in plant cells. Subsequent genetically engineered synthesis of GB-biosynthetic enzymes and studies of transgenic plants demonstrated that accumulation of GB increases tolerance of plants to various abiotic stresses at all stages of their life cycle. Such GB-accumulating plants exhibit various advantageous traits, such as enlarged fruits and flowers and/or increased seed number under non-stress conditions. However, levels of GB in transgenic GB-accumulating plants are relatively low being, generally, in the millimolar range. Nonetheless, these low levels of GB confer considerable tolerance to various stresses, without necessarily contributing significantly to cellular osmotic potential. Moreover, low levels of GB, applied exogenously or generated by transgenes for GB biosynthesis, can induce the expression of certain stress-responsive genes, including those for enzymes that scavenge reactive oxygen species. Thus, transgenic approaches that increase tolerance to abiotic stress have enhanced our understanding of mechanisms that protect plants against such stress.

Glycinebetaine protects plants against abiotic stress: mechanisms and biotechnological applications.

SUMMARY Basidiomycete fungi subsist on various types of plant material in diverse environments, from living and dead trees and forest litter to crops and grasses and to decaying plant matter in soils. Due to the variation in their natural carbon sources, basidiomycetes have highly varied plant-polysaccharide-degrading capabilities. This topic is not as well studied for basidiomycetes as for ascomycete fungi, which are the main sources of knowledge on fungal plant polysaccharide degradation. Research on plant-biomass-decaying fungi has focused on isolating enzymes for current and future applications, such as for the production of fuels, the food industry, and waste treatment. More recently, genomic studies of basidiomycete fungi have provided a profound view of the plant-biomass-degrading potential of wood-rotting, litter-decomposing, plant-pathogenic, and ectomycorrhizal (ECM) basidiomycetes. This review summarizes the current knowledge on plant polysaccharide depolymerization by basidiomycete species from diverse habitats. In addition, these data are compared to those for the most broadly studied ascomycete genus, Aspergillus, to provide insight into specific features of basidiomycetes with respect to plant polysaccharide degradation.

Plant-Polysaccharide-Degrading Enzymes from Basidiomycetes

The native chemical ligation reaction (NCL) involves reacting a C-terminal peptide thioester with an N-terminal cysteinyl peptide to produce a native peptide bond between the two fragments. This reaction has considerably extended the size of polypeptides and proteins that can be produced by total synthesis and has also numerous applications in bioconjugation, polymer synthesis, material science, and micro- and nanotechnology research. The aim of the present review is to provide a thorough mechanistic overview of NCL and extended methods. The most relevant properties of peptide thioesters, Cys peptides, and common solvents, reagents, additives, and catalysts used for these ligations are presented. Mechanisms, selectivity and reactivity are, whenever possible, discussed through the insights of computational and physical chemistry studies. The inherent limitations of NCL are discussed with insights from the mechanistic standpoint. This review also presents a palette of O, S-, N, S-, or N, Se-acyl shift systems as thioester or selenoester surrogates and discusses the special molecular features that govern reactivity in each case. Finally, the various thiol-based auxiliaries and thiol or selenol amino acid surrogates that have been developed so far are discussed with a special focus on the mechanism of long-range N, S-acyl migrations and selective dechalcogenation reactions.

Native Chemical Ligation and Extended Methods: Mechanisms, Catalysis, Scope, and Limitations

Betaine aldehyde dehydrogenase (BADH; EC 1.2.1.8) is an important enzyme that catalyzes the last step in the synthesis of glycine betaine, a compatible solute accumulated by many plants under various abiotic stresses. In barley (Hordeum vulgare L.), we reported previously the existence of two BADH genes (BBD1 and BBD2) and their corresponding proteins, peroxisomal BADH (BBD1) and cytosolic BADH (BBD2). To investigate their enzymatic properties, we expressed them in Escherichia coli and purified both proteins. Enzymatic analysis indicated that the affinity of BBD2 for betaine aldehyde was reasonable as other plant BADHs, but BBD1 showed extremely low affinity for betaine aldehyde with apparent K(m) of 18.9 microM and 19.9 mM, respectively. In addition, V(max)/K(m) with betaine aldehyde of BBD2 was about 2000-fold higher than that of BBD1, suggesting that BBD2 plays a main role in glycine betaine synthesis in barley plants. However, BBD1 catalyzed the oxidation of omega-aminoaldehydes such as 4-aminobutyraldehyde and 3-aminopropionaldehyde as efficiently as BBD2. We also found that both BBDs oxidized 4-N-trimethylaminobutyraldehyde and 3-N-trimethylaminopropionaldehyde.

Enzymatic characterization of peroxisomal and cytosolic betaine aldehyde dehydrogenases in barley

In the current studies, we sequenced and characterized the genomic and complementary deoxyribonucleic acid clones encoding the cellobiohydrolase encoding genes cel1 and cel2 of Polyporus arcularius. The predicted amino acid sequences of Cel1 and Cel2 are similar to glycosyl hydrolase family 7 and 6 proteins, respectively. The expression of cel1 and cel2 was induced by microcrystalline cellulose (Avicel) and cellopentaose but repressed by glucose, cellobiose, cellotriose, and cellotetraose. There was a very low level of cel1 and cel2 transcription regardless of the carbon source. These results suggest that P. arcularius cells constitutively express a very low level of cellulase that can degrade insoluble crystalline cellulose and that the transcription of cel1 and cel2 in the cells is induced by products produced by these endoglucanases such as cellooligosaccharides.

Transcriptional regulation of two cellobiohydrolase encoding genes (cel1 and cel2) from the wood-degrading basidiomycete Polyporus arcularius

Synthesis of mucin-type glycopeptide (β hCG 130–145) by on-resin fragment condensation of the glycopeptide segments carrying unmasked oligosaccharides

Volatiles produced by mycelia of mushrooms with aromatic odour were investigated for their antifungal activity against plant-pathogenic fungi. The results of the screening of 23 species of basidiomycetes revealed that volatile substances from mycelia of Mycoleptodonoides aitchisonii (TUFC10099), an edible mushroom, strongly inhibited the mycelial growth, spore germination and lesion formation on host leaves of some plant-pathogenic fungi including Alternaria alternata, A. brassicicola, A. brassicae, Colletotrichum orbiculare and Corynespora cassiicola. The volatile compounds were isolated from the culture filtrate of M. aitchisonii, and 1-phenyl-3-pentanone was identified as a major antifungal volatile. The compound had significantly inhibitory activity against plant-pathogenic fungi at 35 ppm. This is the first report that the volatile compound produced by mycelia of M. aitchisonii has antifungal activity against plant-pathogenic fungi.

Tsuyoshi Ichiyanagi

Papers

Enzymatic characterization of peroxisomal and cytosolic betaine aldehyde dehydrogenases in barley

Transcriptional regulation of two cellobiohydrolase encoding genes (cel1 and cel2) from the wood-degrading basidiomycete Polyporus arcularius

Synthesis of mucin-type glycopeptide (β hCG 130–145) by on-resin fragment condensation of the glycopeptide segments carrying unmasked oligosaccharides

1‐Phenyl‐3‐pentanone, a Volatile Compound from the Edible Mushroom Mycoleptodonoides aitchisonii Active Against Some Phytopathogenic Fungi

Gymnopilins, a product of a hallucinogenic mushroom, inhibit the nicotinic acetylcholine receptor.