Nils Birkeland

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Methanotrophs are ubiquitous bacteria that can use the greenhouse gas methane as a sole carbon and energy source for growth, thus playing major roles in global carbon cycles, and in particular, substantially reducing emissions of biologically generated methane to the atmosphere. Despite their importance, and in contrast to organisms that play roles in other(More)
With the aim of gaining insight into the molecular and phylogenetic relationships of isocitrate dehydrogenase (IDH) from hyperthermophiles, we carried out a comparative study of putative IDHs identified in the genomes of the eubacterium Thermotoga maritima and the archaea Aeropyrum pernix and Pyrococcus furiosus. An optimum for activity at 90 degrees C or(More)
Rod-shaped, thermophilic bacteria with a sheath-like outer structure (toga) were isolated from hot oilfield water of a North Sea oil reservoir. One of the isolates, designated SJ95(T), is an obligately anaerobic, sheathed, Gram-negative, fermentative bacterium capable of reducing elemental sulfur to hydrogen sulfide and tolerating high salt concentrations.(More)
Isocitrate dehydrogenase from Archaeoglobus fulgidus (AfIDH) has an apparent melting temperature (T m) of 98.5°C. To identify the structural features involved in thermal stabilization of AfIDH, the structure was solved to 2.5 Å resolution. AfIDH was strikingly similar to mesophilic IDH from Escherichia coli (EcIDH) and displayed almost the same number of(More)
The crystal structure of malate dehydrogenase from the hyperthermophilic archaeon Archeoglobus fulgidus, in complex with its cofactor NAD, was solved at 2.9A resolution. The crystal structure shows a compact homodimer with one coenzyme bound per subunit. The substrate binding site is occupied by a sulphate ion. In order to gain insight into adaptation(More)
Hydrolytic deamination of DNA-cytosines into uracils is a major source of spontaneously induced mutations, and at elevated temperatures the rate of cytosine deamination is increased. Uracil lesions are repaired by the base excision repair pathway, which is initiated by a specific uracil DNA glycosylase enzyme (UDG). The hyperthermophilic archaeon(More)
An integration vector system based on the site-specific integration apparatus of the temperate lactococcal bacteriophage phiLC3 was developed. A 1.6-kb recombinogenic DNA cassette, containing the phiLC3 integrase gene (int) and the phage attachment site (attP), mediated site-specific integration of a single marker-gene, as well as of a(More)
The genes encoding the lysis proteins of Lactococcus lactis bacteriophage phi LC3 were cloned, sequenced, and expressed in Escherichia coli. The phi LC3 lysis genes, lysA and lysB, encode a membrane-disrupting protein (LysA) of 88 amino acids, and a cell wall degrading protein (LysB) of 429 amino acids, which shares significant sequence similarity with(More)
NADP(+)-specific isocitrate dehydrogenase (EC 1.1.1.42) was purified to homogeneity from the sulfate-reducing bacterium Desulfobacter vibrioformis, and shown to be a monomeric protein with a molecular mass of 80 kDa. The pH and temperature optima were 8.5 and 45 degrees C, respectively. The N-terminal amino acid sequence (Thr, Glu, Thr, Ile, Arg, Trp, Thr,(More)
L-Malate (MalDH) and L-lactate (LDH) dehydrogenases belong to the same family of NAD-dependent enzymes. To gain insight into molecular relationships within this family, we studied two hyperthermophilic (LDH-like) L-MalDH (proteins with LDH-like structure and MalDH enzymatic activity) from the archaea Archaeoglobus fulgidus (Af) and Methanococcus jannaschii(More)