Gabriela Pühler

The three-dimensional structure of proteasomes from Thermoplasma acidophilum as determined by electron microscopy using random conical tilting

The three‐dimensional structure of proteasomes from the archaebacterium Thermoplasma acidophilum has been determined to a resolution of approximately 2 nm from electron micrographs of negatively stained preparations using the method of random conical tilting. The particles turn out to be essentially cylinder‐shaped barrels, 15 nm long and 11 nm wide, enclosing a tripartite inner compartiment. An account is given of some of the present limitations which prevent to attain a higher resolution and possible ways to overcome these limitations are indicated.

Picrophilus oshimae and Picrophilus torridus fam. nov., gen. nov., sp. nov., two species of hyperacidophilic, thermophilic, heterotrophic, aerobic archaea

We describe two species of hyperacidophilic, thermophilic, heterotrophic, aerobic archaea that were isolated from solfataric hydrothermal areas in Hokkaido, Japan. These organisms, Picrophilus oshimae and Picrophilus torridus, represent a novel genus and a novel family, the Picrophilaceae, in the kingdom Euryarchaeota and the order Thermoplasmales. Both of these bacteria are more acidophilic than the genus Thermoplasma since they are able to grow at about pH 0.

Proteasomes: Multisubunit Proteinases common to Thermoplasma and Eukaryotes

Abstract We have examined a large number of archaea from all the major lineages and some bacteria with respect to the occurrence of proteasomes. Using three different assays for detection, the data we obtained suggest that proteasomes occur exclusively in the genus Thermoplasma . Albeit much simpler in subunit composition, the Thermoplasma proteasomes are remarkably similar in primary structure and subunit organization of the complex to proteasomes from higher eukaryotes. Our findings have some interesting implications. Firstly, they show that eukaryotic proteasomes have evolved from their evolutionary antecedents by multiple gene duplications of the two (α and β) subunits. Secondly, they indicate that ubiquitin-dependent proteolysis has developed rather early in evolution. Thirdly, they raise doubts about the present placement of Thermoplasma within the archaea.

Organisation and Nucleotide Sequence of a Gene Cluster Comprising the Translation Elongation Factor 1α from Sulfolobus acidocaldarius

Summary The gene encoding elongation factor EF-1α from Sulfolobus acidocaldarius was localised to a 4200 bp EcoRI fragment of plasmid pIN IIIA (Puhler, G. et al, 1989, Nucleic Acids Res. 17, 4517–4534). Sequence analysis of this DNA fragment revealed the existence of the genes for ribosomal protein S7, elongation factor EF-1α, ribosomal protein S10 and transfer RNASer (GGA). Analysis of transcripts derived from this chromosomal region showed that these genes are co-transcribed. Additional promoters, which are situated within this transcriptional unit, and several sites of putative transcriptional termination or processing were identified. The organisation of the genes is very similar to that of homologous genes comprising the “streptomycin operon” in Methanococcus vannielii and in Bacteria, apart from the fact that the gene for elongation factor EF-2 is not located in this transcriptional unit. A phylogenetic tree based on the comparison of EF-1α/Tu sequences from Archaea1, Bacteria and Eucarya supports the concept of the monophyletic origin of the archaeal kingdom and shows that Archaea have a smaller evolutionary distance to Eucarya than to Bacteria.

Phylogeny of DNA-Dependent RNA Polymerases: Testimony for the Origin of Eukaryotes

The organization of the genes for the large components of DNA-dependent RNA polymerase in archaebacteria resembles that in eubacteria.