Acquired Thermotolerance and Stressed-Phase Growth of the Extremely Thermoacidophilic Archaeon Metallosphaera sedula in Continuous Culture

Abstract

The response of an extremely thermoacidophilic archaeon, Metallosphaera sedula (growth temperature range, 50 to 79°C; optimum temperature, 74°C; optimum pH, 2.0), to thermal stress was investigated by using a 10-liter continuous cultivation system. M. sedula, growing at 74°C, pH 2.0, and a dilution rate of 0.04 hr ؊1 , was subjected to both abrupt and gradual temperature shifts in continuous culture to determine the responses of cell density levels and protein synthesis patterns. An abrupt temperature shift from 74 to 79°C resulted in little, if any, changes in cell density and a small increase in total protein per cell. When the culture temperature was shifted further to 80.5°C, cell density dropped to below 5 ؋ 10 6 cells/ml from 10 8 cells/ml, leading to washout of the culture. Operation at this temperature and slightly higher temperatures, however, could be achieved by exposing the culture to thermal stress more gradually (0.5°C increments). As a result, stable operation could be maintained at temperatures of up to 81°C, and the washout temperature could be increased to 82.5°C. Continuous culture operation at 81°C for 100 h (stressed phase) led to an approximately sevenfold lower steady-state cell density than that observed for operation at or below 79°C. However, sodium dodecyl sulfatepolyacrylamide gel electrophoresis analysis (both one and two dimensional) revealed significantly higher levels (sixfold increase) of a 66-kDa stress response protein (MseHSP60), immunologically related to Thermophilic Factor 55 from Sulfolobus shibatae (

Acquired Thermotolerance and Temperature-Induced Protein Accumulation in the Extremely Thermophilic Bacterium Rhodothermus obamensis

“…In the members of the order Sulfolobales, prominent heat shock proteins with subunit molecular masses of approximately 60 kDa have been reported (36). These major heat shock proteins are thermophilic factor 55 and its relatives and are similar to a eukaryotic protein family known as t-complex polypeptide 1 (13,21,27,34,35). It has also been suggested that these proteins are involved in the heat shock response and thermal acclimation in the thermoacidophilic archaea (11).…”

“…The amino acid sequence AVLEIRNLHARVEEKEILK GVNLTVNAG was the same in all three HSP35s, and the sequence of all three HGP30s was NAVDEYIPTPVRDKD-KPFLMPIEDV. Multi-isoelectric heat shock proteins were often observed in prokaryotic and eukaryotic cells based on 2-D polyacrylamide gel electrophoresis (13,20). The amino acid sequences of HSP35s and HGP30s were analyzed by using the basic local alignment search tool (1) to estimate the degree of similarity to other amino acid sequences (Fig.…”

“…These HSP35s and HGP30s consisted of multi-isoelectric isoforms. It has been reported that several stress proteins also had isoforms with different isoelectric points, which were due to posttranslational modification such as phosphorylation and adenylylation (13,20). In addition, the isoform compositions of the HSP35s of optimal-temperaturegrown and heat-shocked cells differed.…”

Untersuchung der Stressantwort von <i>Picrophilus torridus</i> mittels 2D-Gelelektrophorese und Charakterisierung ausgewählter Dehydrogenase

“…Die am besten charakterisierte Stressantwort ist die Hitzeschock-Antwort. Diese wurde schon an einer Vielzahl von Eukaryoten und Bakterien (Bardwell and Craig, 1984;Hebert et al, 1991;Hecker et al, 1996;VanBogelen et al, 1987a), aber auch an einigen Archaeen untersucht (Han et al, 1997;Hebert et al, 1991;Shockley et al, 2003;Tachdjian and Kelly, 2006;Trent et al, 1990).…”

Continuous growth and heat shock of thermoacidophilic Sulfolobus in a triple-stage chemostat for overexpression and isolation of chaperonin

“…The review focuses on the htpG heat shock gene as a response indicator, and states that expression is dependent on both rate and intensity of the stress, but is independent of growth rate. The work ofHan, Park, & Kelly (1997) is related to the work described here. A single stage continuous culture was used to investigate the heat shock response of Metallosphaera sedula, an organism in the same family (Sulfolobaceae) as genus Sulfolobus.…”