Resistance to protein synthesis inhibitors in Coprinus cinereus

Traynor, John David (1983) Resistance to protein synthesis inhibitors in Coprinus cinereus. Doctoral thesis, City of London Polytechnic.


Cycloheximide, a potent eukaryotic protein synthesis inhibitor (Sisler and Siegel, 1967) was used in a biochemical and genetical investigation of the beisidiomycete fungus, Coprinus cinereus.

An optimised polyuridylic acid dependant cell-free polyphenylalanine synthesising system was developed for Coprinus cinereus, in order to identify the cellular component conferring cycloheximide-resistance in two cycloheximide-resistant mutant strains, CY 8.2 and CY9.23 In both of these strains, resistance to cycloheximide was found to be associated with the cytoplasmic ribosome fraction. It was not possible to Identify the particular cytoplasmic ribosomal subunit which conferred cycloheximide-resistance.

Analysis of cytoplasmic ribosomal proteins by two-dimensional gel electrophoresis did not reveaú. any difference between the small subunit proteins of CY 8 and CY 8.2. There were a considerable number of differences between the proteins extracted from the large subunit of CY 8 and CY 8.2, and CY 9 and CY9.23. There wan no conclusive evidence to identify a cytoplasmic ribosomal protein associated with cycloheximide resistance although several candidates were proposed. An analysis using carboxymethyl-cellulose chromotography did not Identify any cytoplasmic ribosomal proteins conferring cycloheximide resistance.

CY 8.2 was one of 174 cycloheximide-resistant mutant strains produced by the ultraviolet mutagenesis of cycloheximide-sensitive strains, according to a method modified from North (1982). Cycloheximide- resistance in each mutant strain was considered to be conferred a single gene, which in those strains examined, was recessive in heterozygous cycloheximide-resistant dikaryons and diploids . The cycloheximide-resistance mutation in all strains examined belonged to the cy-2 complementation group (North, 1982) and hence were allelic with the resistance gene carried by CY 9.23. A classification of the cycloheximide-resistant mutants was proposed on the basis of their growth responses to cycloheximide.

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