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The functional and biological significance of selected CASP13 targets are described by the authors of the structures. The structural biologists discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP13 experiment.

Basidiomycota (basidiomycetes) make up 32percent of the described fungi and include most wood decaying species, as well as pathogens and mutualistic symbionts. Wood-decaying basidiomycetes have typically been classified as either white rot or brown rot, based on the ability (in white rot only) to degrade lignin along with cellulose and hemicellulose. Prior genomic comparisons suggested that the two decay modes can be distinguished based on the presence or absence of ligninolytic class II peroxidases (PODs), as well as the abundance of enzymes acting directly on crystalline cellulose (reduced in brown rot). To assess the generality of the white rot/brown rot classification paradigm we compared the genomes of 33 basidiomycetes, including four newly sequenced wood decayers, and performed phylogenetically-informed Principal Components Analysis (PCA) of a broad range of gene families encoding plant biomass-degrading enzymes. The newly sequenced Botryobasidium botryosum and Jaapia argillacea genomes lack PODs, but possess diverse enzymes acting on crystalline cellulose, and they group close to the model white rot species Phanerochaete chrysosporium in the PCA. Furthermore, laboratory assays showed that both B. botryosum and J. argillacea can degrade all polymeric components of woody plant cell walls, a characteristic of white rot. We also found expansions in reducing polyketide synthase genes specific to the brown rot fungi. Our results suggest a continuum rather than a dichotomy between the white rot and brown rot modes of wooddecay. A more nuanced categorization of rot types is needed, based on an improved understanding of the genomics and biochemistry of wood decay.

Results reveal that Cochliobolus carbonum produces two types of histone deacetylases, a toxin-resistant and other toxin-sensitive forms. Data indicate that inhibitor-resistant activity is displayed by the toxin-producing form.

Research has been conducted on the posttranslational core histone acetylation. The identification of two maize histone deacetylase forms by purification and cDNA cloning is described.

Results reveal that TOXF gene has a role in the HC-toxin production and pathogenicity of Cochliobolus carbonum. The amino acid sequence data show homology to branched-chain-amino-acid transaminases from other species.

A study was conducted to analyze a novel eukaryotic beta-xylosidase (Xyp1) gene from the phytopathogenic fungus Cochliobolus carbonum. cDNA and genomic DNA encoding Xyp1 were determined using polymerase chain reaction primers based on peptide sequences from the purified protein. Results indicated that the mutation of the XYP1 by targeted gene replacement led to the loss of the major beta-xylosidase activity correlated with the product of XYP1.

Research was conducted to examine the targeted mutants of Cochliobolus carbonum lacking the two major extracellular polygalacturonases (exoPG). The purification of the exoPG activity of C carbonum and the cloning of its gene, PGX1, was also performed. Double pgn1/pgx1 mutant strain was developed by crossing. The continued growth of the pgn1/pgx1 mutant strain on pectin could be attributed to one or more of PG residual activities.

Mixed-linked glucanases (MLGases) or extracellular enzymes that degrade beta-glucan from the fungus Cochliobolus carbonum were identified and characterized. Three peaks of MLGase activity, named Mlg1a, Mlg1b and Mlg2, were resolved by hydrophobic-interaction high performance liquid chromatography and cation-exchange. Results showed that the N-terminal amino acid sequences of Mlg1a and Mlg1b were identical. Mlg1a was glycosylated while Mlg1b was not. Mlg1a and Mlg1b hydrolyzed beta1,3-glucan while Mlg2 did not.

The filamentous fungi Cochliobolus carbonum contains three cationic xylanases, XYL1, XYL2 and XYL3 that encode for the extracellular 22-kDa family of G xylanases. XYL1 and XYL3 mRNA's are present in infected plants. XYL2 and XYL3 have no contribution towards the extracellular xylanase activity. Multiple xylanase disruptions are produced by crossing single xylanase mutants. The triple mutant is still pathogenic on maize as evident from its lesion size, morphology and rate of lesion development.

The TOXA gene of the plant-pathogen fungus, Cochliobolus carbonum, encodes an HC-toxin efflux pump which plays a role in self-protection against HC-toxin. The gene is present only in the fungal isolates that make HC-toxin, and it occurs as two linked copies. TOXA occurs close to HTS1, the gene found in HC-toxin making fungal isolates, that codes for the enzyme necessary for the synthesis of HC-toxin. The amino acid sequence of TOXA gene is discussed.

Cochliobolus carbonum, the phytopathogenic fungus, generates an enzyme that degrades beta1,3-glucanase, and the purified enzyme is used to isolate the gene EXGI from genomic DNA. EXG1 mutant growth is normal on oat bran and sucrase, but reveals a 65% decrease on pure beta1, 3-glucan. EXG1 mutant has been found to be pathogenic to maize.