Bacterium Desulfovibrio Gigas Research Articles

The amino acid sequence of rubredoxin from the sulfate reducing bacterium, [formula omitted][formula omitted

Determination of the complete amino acid sequence of the rubredoxin isolated from the sulfate reducing bacterium Desulfovibrio gigas showed that the molecule consists of a single polypeptide chain of 52 residues. The sequence of the first 42 residues was determined using an automatic Protein Sequencer. Peptides derived from tryptic hydrolysis and from specific cleavage at tryptophan residue were used to construct the total sequence. Compared with the sequence of Desulfovibrio vulgaris rubredoxin, 37 positions are identical, and with the sequences of Clostridium pasteurianum , Peptostreptococcus elsdenii , Micrococcus aerogenes and D. vulgaris rubredoxins, 20 matching residues occur. A crystallographic study of the D. gigas rubredoxin is in progress.

Localized intracellular polyphosphate formation by Desulfovibrio gigas.

The dissimilatory sulphate-reducing bacterium Desulfovibrio gigas, frequently sub-cultured, often contained spherical granules which stained metachromatically with some basic dyes. The granules were examined in situ by transmission electron microscopy of whole organisms and thin sections. The granules were isolated from broken bacteria as a water-insoluble, non-crystalline, white material containing magnesium, phosphorus and organic carbon, but devoid of sulphur and nitrogen. The molar ratio of phosphorus to magnesium (1 to 17) was close to the proportions in magnesium tripolyphosphate. Infrared absorption spectra for the white material and magnesium tripolyphosphate were similar.

Purification and properties of thiosulfate reductase from Desulfovibrio gigas

Thiosulfate reductase of the dissimilatory sulfate-reducing bacterium Desulfovibrio gigas has been purified 415-fold and its properties investigated. The enzyme was unstable during the different steps of purification as well as during storage at - 15 degrees C. The molecular weight of thiosulfate reductase estimated from the chromatographic behaviour of the enzyme on Sephadex G-200 was close to 220000. The absorption spectrum of the purified enzyme exhibited a protein peak at 278 nm without characteristic features in the visible region. Thiosulfate reductase catalyzed the stoichiometric production of hydrogen sulfide and sulfite from thiosulfate, and exhibited tetrathionate reductase activity. It did not show sulfite reductase activity. The optimum pH of thiosulfate reduction occurred between pH 7.4 and 8.0 and its Km value for thiosulfate was calculated to be 5 - 10(-4)M. The sensitivity of thiosulfate reductase to sulfhydryl reagent and the reversal of the inhibition by cysteine indicated that one or more sulfhydryl groups were involved in the catalytic activity. The study of electron transport between hydrogenase and thiosulfate reductase showed that the most efficient coupling was obtained with a system containing cytochromes c3 (Mr = 13000) and c3 (Mr = 26000).

An iron tetrahydroporphyrin prosthetic group common to both assimilatory and dissimilatory sulfite reductases

The heme † † The terms “heme” and “porphin” are used as defined in Ref. 1 and 6. chromophore of the “assimilatory” E. coli sulfite reductase is an iron-octacarboxylic tetrahydroporphyrin of the isobacteriochlorin type (1). Although the two “dissimilatory” sulfite reductases, desulfoviridin and desulforubidin, from the sulfate reducing bacteria Desulfovibrio gigas and Desulfovibrio desulfuricans (Norway strain), have absorption spectra and reaction products which differ from those of E. coli sulfite reductase, the present studies indicate that they contain prosthetic groups with an organic structure closely similar or identical to that of the E. coli sulfite reductase heme. EPR spectra show high-spin ferriheme in all three enzymes. It is clear, however, that the prosthetic groups must reside in substantially different environments within their respective proteins.

Evidence for the presence of a b-type cytochrome in the sulfate-reducing bacterium Desulfovibrio gigas, and its role in the reduction of fumarate by molecular hydrogen

1. The H 2:fumarate reductase activities of particulate fractions prepared from Desulfovibrio gigas grown on various media (lactate-sulfate, fumarate or fumarate-sulfate) were measured. Activity was higher in the particulate fraction prepared from cells grown on fumarate or fumarate-sulfate media than in those prepared from cells cultivated on lactate-sulfate. 2. Various inhibitors were tested for their effect on fumarate reduction by H 2 in a particulate fraction of Desulfovibrio gigas. A strong inhibitory effect was observed with 2-hetyl-4-hydroxyquinoline- N-oxide and antimycin A. These compounds act as inhibitors of an intermediary electron carrier between hydrogenase and fumarate reductase. 3. The strict anaerobe Desulfovibrio gigas has been found to contain a b-type cytochrome linked to the particulate H 2:fumarate reductase activity. A protoheme obtained by extraction from the particulate fraction was characterized by its reduced pyridine hemochromogen.

Purification of the enzyme reducing bisulfite to trithionate from Desulfovibrio gigas and its identification as desulfoviridin

An enzyme which catalyzes the reductive formation of trithionate from sulfite is present in extracts of the sulfate reducing bacterium Desulfovibrio gigas and has been termed, bisulfite reductase. This activity has been purified and the enzyme identified as the green pigment, desulfoviridin, by gel electrophoresis and ultracentrifugation. The stoichiometry of the reduction of sulfite to trithionate is established and some physical properties of the enzyme reported.