Biomedical subjects

E S Haas

Publications and source records attributed to E S Haas.

21 records · Page 2Linked to original sources

PubMed1989

Genes encoding 5S rRNA and tRNAs in the extremely thermophilic archaebacterium Methanothermus fervidus.

Methanothermus fervidus was shown to have two 5S rRNA-encoding genes linked in rRNA operons to 16S and 23S rRNA-encoding genes. Sequencing of a cloned 5S rRNA gene confirmed that M. fervidus is a member of the Methanobacteriales, although its 5S rRNA is also similar in both primary sequence and predicted secondary structure to the 5S rRNA of the non-methanogenic, but also extremely thermophilic archaebacterium, Thermococcus celer. Two clusters of tRNA genes have also been cloned and sequenced form M. fervidus. The smaller cluster, cloned in pET5401, is composed of 5'-tRNA(UGUThr)-tRNA(UGGPro)-tRNA(GUCAsp)-tRNA(UUUL ys)-3' and the larger cluster, cloned in pET5475, is composed of 5'-tRNA(GUUAsn)-tRNA(CAUMet)-tRNA(UUCGlu)-tRNA(UAGL eu)-tRNA(GUGHis)-3'. The encoded tRNAs, with the exception of the tRNA(Leu), translate abundant codons in M. fervidus. The tRNA genes do not contain introns or encode 3'-terminal CCA residues. Homologous clusters of tRNA genes have been sequenced from Methanococcus vannielii and Methanococcus voltae, so that comparisons of transcription signals, gene organizations and primary sequences can be made and features possibly related to thermostability identified. During evolution, a 5S rRNA gene appears to have been incorporated into the cluster of tRNA genes in the methanococci but not in M. fervidus.

Amino Acid Sequence↗

PubMed1986

Molecular cloning of virulence genes from Erwinia stewartii.

A library of Erwinia stewartii DNA was constructed in cosmid pVK100 and used to complement spontaneous and Mu pf7701-induced (designated by the prefix MU) avirulent mutants. Plasmid pES4507 restored water-soaking ability and extracellular polysaccharide (EPS) synthesis to mutants MU14110 and MU2B70 (group I); pES1044 restored water-soaking ability to MU43, MU51, MU136, MU141, and RDF6011 (group II); and pES2144 complemented four spontaneous EPS- mutants (group III). Hybridization of labeled plasmid DNA to Southern blots of genomic DNA from the mutants revealed that a Mu pf7701 insertion was associated with the respective cloned region in all mutants except MU2B70 and MU223. In these strains, the plasmid may be suppressing the avirulent phenotype rather than complementing the mutation.

Cloning, Molecular↗

PubMedDate not supplied

Ribonuclease P structure and function in Archaea.

An important approach to understanding RNA-based catalytic function by ribonuclease P is the investigation of its evolutionary diversity in structure and function. Because RNase P enzymes from all organisms are thought to share common ancestry, the fundamental features of structure and biochemistry should be conserved in all of its modern forms. In contrast to the bacterial enzyme, the RNase P enzymes from Eucarya, organelles, and Archaea are poorly understood. This review describes our nascent understanding of the structure and function of RNase P in Archaea, and how this enzyme compares to its homologs in the other evolutionary Domains.

Archaea↗