%0 
%0 Journal Article
%A Glaeser, Jens; Zobawa, Monica; Lottspeich, Friedrich & Klug, Gabriele
%D 2007
%T Protein synthesis patterns reveal a complex regulatory response to singlet oxygen in Rhodobacter
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%B Journal of proteome research
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%I 
%V 6
%6
%N 
%P 2460-71
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%Y 
%S 
%7
%8 July
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%@ 15353893
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%F glaeser_protein_2007
%K Bacterial Bacterial_Proteins Catalase Cations Divalent Electrophoresis Gel Gene_Expression_Regulation Host_Factor_1_Protein Hydrogen_Peroxide IFZ Light Messenger Mutation Protein_Biosynthesis Proteome RNA Reactive_Oxygen_Species Rhodobacter_sphaeroides Sigma_Factor Singlet_Oxygen Transcription_Factors Two-Dimensional 
%X Singlet oxygen (1O2) is a stress factor and signal in the facultative phototrophic bacterium Rhodobacter sphaeroides. In vivo protein labeling with L-[35S]-methionine and analysis by two-dimensional gel electrophoresis revealed that the synthesis of 61 proteins was changed in response to 1O2. After 1O2 treatment, protein synthesis patterns were distinct from those after H2O2 treatment but similar to those after high light exposure. This indicates regulatory mechanisms selective for different reactive oxygen species (ROS) and a response to light partly mediated by 1O2. Analysis of mutant strains support that the response to 1O2 is regulated mainly by rpoE (sigma E), but also a modulation of the sigma E dependent response by other factors and the existence of sigma E independent responses. The involvement of the RNA chaperon Hfq in the 1O2 response implies a role of small regulatory RNAs.
%Z PMID: 17536848
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%0 
%0 Journal Article
%A Hundt, Sonja; Zaigler, Alexander; Lange, Christian; Soppa, Jörg & Klug, Gabriele
%D 2007
%T Global analysis of mRNA decay in Halobacterium salinarum NRC-1 at single-gene resolution using DNA microarrays
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%B Journal of bacteriology
%C 
%I 
%V 189
%6
%N 
%P 6936-44
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%Y 
%S 
%7
%8 October
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%@ 00219193
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%F hundt_global_2007
%K Archaeal Blotting Dactinomycin Genetic Genome Half-Life Halobacterium_salinarum IFZ Messenger Northern Oligonucleotide_Array_Sequence_Analysis RNA RNA_Stability Transcription 
%X RNA degradation is an important factor in the regulation of gene expression. It allows organisms to quickly respond to changing environmental conditions by adapting the expression of individual genes. The stability of individual mRNAs within an organism varies considerably, contributing to differential amounts of proteins expressed. In this study we used DNA microarrays to analyze mRNA degradation in exponentially growing cultures of the extremely halophilic euryarchaeon Halobacterium salinarum NRC-1 on a global level. We determined mRNA half-lives for 1,717 open reading frames, 620 of which are part of known or predicted operons. Under the tested conditions transcript stabilities ranged from 5 min to more than 18 min, with 79\% of the evaluated mRNAs showing half-lives between 8 and 12 min. The overall mean half-life was 10 min, which is considerably longer than the ones found in the other prokaryotes investigated thus far. As previously observed in Escherichia coli and Saccharomyces cerevisiae, we could not detect a significant correlation between transcript length and transcript stability, but there was a relationship between gene function and transcript stability. Genes that are known or predicted to be transcribed in operons exhibited similar mRNA half-lives. These results provide initial insights into mRNA turnover in a euryarchaeon. Moreover, our model organism, H. salinarum NRC-1, is one of just two archaea sequenced to date that are missing the core subunits of the archaeal exosome. This complex orthologous to the RNA degrading exosome of eukarya is found in all other archaeal genomes sequenced thus far.
%Z PMID: 17644597
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%0 
%0 Journal Article
%A Wagner, Steffen & Klug, Gabriele
%D 2007
%T An archaeal protein with homology to the eukaryotic translation initiation factor 5A shows ribonucleolytic activity
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%B The Journal of biological chemistry
%C 
%I 
%V 282
%6
%N 
%P 13966-76
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%Y 
%S 
%7
%8 May
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%@ 00219258
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%F wagner_archaeal_2007
%K Amino_Acid_Sequence Archaeal Archaeal_Proteins Base_Sequence Cells Cultured Eukaryotic_Cells Genetic_Vectors Halobacterium IFZ Ligands Lysine Messenger Molecular_Sequence_Data Nucleic_Acid Nucleic_Acid_Conformation Peptide_Initiation_Factors Post-Translational Protein_Processing RNA RNA-Binding_Proteins Ribonucleases Sequence_Homology 
%X To identify proteins that are involved in RNA degradation and processing in Halobacterium sp. NRC-1, we purified proteins with RNA-degrading activity by classical biochemical techniques. One of these proteins showed strong homology to the eukaryotic initiation factor 5A (eIF-5A) and was accordingly named archaeal initiation factor 5A (aIF-5A). Eukaryotic IF-5A is known to be involved in mRNA turnover and to bind RNA. Hypusination of eIF-5A is required for sequence-specific binding of RNA. This unique post-translational modification is restricted to Eukarya and Archaea. The exact function of eIF-5A in RNA turnover remained obscure. Here we show for the first time that aIF-5A from Halobacterium sp. NRC-1 exhibits RNA cleavage activity, preferentially cleaving adjacent to A nucleotides. Detectable RNA binding could be shown for aIF-5A purified from Halobacterium sp. NRC-1 but not from Escherichia coli, while both proteins possess RNA cleavage activity, indicating that hypusination of aIF-5A is required for RNA binding but not for its RNA cleavage activity. Furthermore, we show that the hypusinated form of eIF-5A also shows RNase activity while the unmodified protein does not. Charged amino acids in the N-terminal domain of aIF-5A as well as in the C-terminal domain, which is highly similar to the cold shock protein A (CspA), an RNA chaperone of E. coli, are important for RNA cleavage activity. Moreover our results reveal that activity of aIF-5A depends on its oligomeric state.
%Z PMID: 17369252
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