Project description:Two c-type cytochromes from the soluble fraction of a deep-sea moderately piezophilic bacterium, Shewanella violacea, were purified and characterized, and the genes coding for these cytochromes were cloned and sequenced. One of the cytochromes, designated cytochrome c(A), was found to have a molecular mass of approximately 8.3 kDa, and it contained one heme c per molecule. The other, designated cytochrome c(B), was found to have a molecular mass of approximately 23 kDa, and it contained two heme c molecules per protein molecule. The amount of cytochrome c(B) expressed in cells grown at high hydrostatic pressure (50 MPa) was less than that in cells grown at atmospheric pressure, whereas cytochrome c(A) was constitutively expressed under all pressure conditions examined. The results of Northern blotting analysis were consistent with the above-mentioned observations and suggested that the pressure regulation of cytochrome c(B) gene expression occurred at the transcriptional level. These results suggest that the components of the respiratory chain of moderately piezophilic S. violacea could be exchanged according to the growth pressure conditions.
Project description:Barophilic growth of the hyperthermophilic methanarchaeon Methanocaldococcus jannaschii occurred when gas-substrate availability did not limit growth. In contrast, when growth was limited by gas transfer, no enhancement of growth was evident and a stress response was exhibited at both high and low pressure. A pressure-induced transcriptional response was evident, regardless of whether growth was enhanced by pressure. High-pressure adaptation of a barophilic organism can thus occur at the transcriptional level, even though the cells are stressed by low substrate availability and do not exhibit accelerated growth. Keywords: stress response, gas substrate limitation, bioreactor volume, high pressure
