Thermoplasma acidophilum (T. acidophilum), an obligatory acidophilic and thermophilic organism contains one of the smallest genomes (1.5 Mbp). Due to its simplicity, it is an excellent model for studying its proteins and for the comparison with corresponding proteins of higher organisms. The sequencing of its entire genome has provided an enormous amount of information: 55% of its chromosomal coding sequences have similarity to known proteins from all domains of life (archaea, bacteria, and eukarya), 29% have similarity to proteins of unknown function, and the remaining 16% contain no assignable information. Within the 29% of coding sequences without a known function, a set of proteins from the superfamily of ATPases associated with various activities (AAA+ family) was found. AAA+ proteins are a family of enzymatic machines involved in diverse cellular functions ranging from DNA repair and replication to organelle biogenesis, membrane trafficking, transcriptional regulation, and protein quality control. The T. acidophilum genome is lacking the presence of the AAA-regulatory particle of the 26S proteasome of eukaryotes, or the archaeal PAN in Methanococcus jannaschii, which are needed to unfold and disaggregate protein substrates and to facilitate their entry into the chamber which harbors the proteolytic active sites in proteasomes. Therefore, it was of particular interest to find out if one of the AAA+ proteins (VAT, Lon-2, and/or TAA43) found in T. acidophilum could participate directly or indirectly in the ATP- and proteasome-dependent protein degradation pathway. The T. acidophilum ORF 1175 (namely TAA43) was selected for such investigation. In vitro and in vivo interaction analyses provide a hint of AAA+ TAA43 protein as associated with proteins found in two major molecular machineries of the cell, the transcription and the translation apparatus, thus discarding the hypothesis proposed above. Analysis of the gene organization of T. acidophilum indicates the taa43 ORF to be in close proximity to genetic elements resembling a superoperon (a cluster of genes composed by ribosomal proteins, a DNA-directed RNA polymerase subunit, and transfer RNAs, among others).     «

Thermoplasma acidophilum (T. acidophilum), an obligatory acidophilic and thermophilic organism contains one of the smallest genomes (1.5 Mbp). Due to its simplicity, it is an excellent model for studying its proteins and for the comparison with corresponding proteins of higher organisms. The sequencing of its entire genome has provided an enormous amount of information: 55% of its chromosomal coding sequences have similarity to known proteins from all domains of life (archaea, bacteria, and euka...     »

Der in dieser Arbeit bei der Sequenzierung des Genoms von Thermoplasma acidophilum identifizierte ORF 1175 kodiert für ein Protein, TAA43, das ein Mitglied der AAA ATPase Familie ist. Da der kanonische archaebakterielle AAA ATPase Aktivator des Proteasoms in Thermoplasma nicht gefunden wurde, kam TAA43 als potentieller Aktivator des Proteasoms in Betracht. In vitro Rekonstitutionsversuche und Immunoprezipitationsstudien zeigten jedoch, dass TAA43 keine Funktion im ATP- und Proteasomen-abhängigen Proteinabbauweg hat. Dagegen weisen in vitro und in vivo Interaktionsstudien darauf hin, dass TAA43 mit Proteinen des Transkriptions- bzw. Translationsapparates interagiert.     «

Der in dieser Arbeit bei der Sequenzierung des Genoms von Thermoplasma acidophilum identifizierte ORF 1175 kodiert für ein Protein, TAA43, das ein Mitglied der AAA ATPase Familie ist. Da der kanonische archaebakterielle AAA ATPase Aktivator des Proteasoms in Thermoplasma nicht gefunden wurde, kam TAA43 als potentieller Aktivator des Proteasoms in Betracht. In vitro Rekonstitutionsversuche und Immunoprezipitationsstudien zeigten jedoch, dass TAA43 keine Funktion im ATP- und Proteasomen-abhängigen...     »