Age dependent changes in fungi: ribosomes and protein synthesis in Rhizoctonia solani mycelium

The interaction pattern between a homology model of 40S ribosomal S9 protein of Rhizoctonia solani and 1-hydroxyphenaize by docking study

1-Hydroxyphenazine (1-OH-PHZ), a natural product from Pseudomonas aeruginosa strain SD12, was earlier reported to have potent antifungal activity against Rhizoctonia solani. In the present work, the antifungal activity of 1-OH-PHZ on 40S ribosomal S9 protein was validated by molecular docking approach. 1-OH-PHZ showed interaction with two polar contacts with residues, Arg69 and Phe19, which inhibits the synthesis of fungal protein. Our study reveals that 1-OH-PHZ can be a potent inhibitor of 40S ribosomal S9 protein of R. solani that may be a promising approach for the management of fungal diseases.

Changes in ribonuclease with age in the fungus Rhizoctonia solani

The enzyme ribonuclease (RNase) which was isolated from Rhizoctonia solani Kuehn degraded ribonucleic acid from both Torula yeast and from Rhizoctonia solani mycelia. As the Rhizoctonia mycelia aged, there was an increase in both the total and the specific activities of the RNase present in the mycelia. This change is discussed in relation to the age dependent decrease in protein synthesis in this fungus.

Age-related changes associated with the induction of o-pyrocatechuic acid carboxylase in Aspergillus ornatus

Mycelial mats of Aspergillus ornatus grown on cellulose xanthate membranes placed on a defined agar medium showed o-pyrocatechuic acid carboxyalse activity which could be induced to over six times its basal level by the addition of 0.1% L-tryptophan to the medium. Exposure of mature mycelial mats to cyclohexamide prior to induction indicated that de novo protein synthesis was required for this induction to occur. The effect of age of this enzyme adaptation process was investigated by transferring membranes and mats of variuos ages from defined medium to fresh defined medium plus 0.1% L-tryptophan With increasing mycelial age, the basal enzyme activity level remained relatively unchanged while the level to which the enzyme could be induced decreased significantly. This decrease was linear when plotted against the mean cell age of mycelium, conforming to a general model of age-dependent modifications of the enzyme adaptation process proposed by Adelman. Several possible explanations of this phenomenon are discussed.