Physico-chemical Properties of Ribosomal RNA from Thermophilic Fungi

Abstract

<p>Thermophilic fungi have the highest maximum growth temperature (60ºC) of any eukayotic organism. It might, therefore, be expected that its cellular components would have unusual physico-chemical properties resulting in increased thermostability. To investigate this, ribosomes and ribosomal DNA from Chaetomium thermophilic var. coprophile were compared to those of rat liver. Chaetomium cytosol ribosomes were observed to be more thermostable than rat liver ribosomes. However, the opposite relationship was found for their component ribosomal RNAs. These findings suggest that the thermostability of the Chaetomium ribosome results from unique RNA-protein interactions rather than from novel characteristics of its ribosomal RNAs.</p> <p>An examination of Chaetomium mitochondrial ribosomal RNA revealed that in terms of sedimentation properties and electrophoretic mobilities, the two high molecular weight species resembled their cytosol counterparts. However, their G+C contents were intermediate between those of the cytosol RNA's and those of previously studied mitochondrial RNAs from mesophilic fungi. These observations represent the first demonstration in ascomycetes and animal, of mitochondrial ribosomal RNA with properties similar to those of its homologous cytosol immuniites.</p>