Hyperthermophilic microorganisms

Stetter, Karl O.; Fiala, Gerhard; Huber, Gertrud; Huber, Robert; Segerer, Andreas H.

doi:10.1111/j.1574-6968.1990.tb04089.x

Cited by 364 publications

(124 citation statements)

References 37 publications

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“…During the 1980s, organisms were discovered that are capable of survival and growth at temperatures up to 110 mC [1]. Most biochemists accept that an integral feature of such extremely thermophilic organisms are enzymes that are stable in i o at these temperatures.…”

Section: Introductionmentioning

confidence: 99%

The denaturation and degradation of stable enzymes at high temperatures

Daniel

Dines

Petach³

1996

Biochemical Journal

263

174

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Now that enzymes are available that are stable above 100 mC it is possible to investigate conformational stability at this temperature, and also the effect of high-temperature degradative reactions in functioning enzymes and the inter-relationship between degradation and denaturation. The conformational stability of proteins depends upon stabilizing forces arising from a large number of weak interactions, which are opposed by an almost equally large destabilizing force due mostly to conformational entropy. The difference between these, the net free energy of stabilization, is relatively small, equivalent to a few interactions. The enhanced stability of very stable proteins can be achieved by an additional stabilizing force which is again equivalent to only a few stabilizing interactions. There is currently no strong evidence that any particular interaction (e.g. hydrogen bonds, hydrophobic interactions) plays a more important role in

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Section: Introductionmentioning

confidence: 99%

The denaturation and degradation of stable enzymes at high temperatures

Daniel

Dines

Petach³

1996

Biochemical Journal

263

174

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“…A variety of so-called hyperthermophilic microorganisms have been isolated in recent years (Stetter et al, 1990;Adams, 1990;Stetter, 1986) in the vicinity of both terrestrial and submarine hydrothermal vents. The majority of them are classified as Archaea (Woese et al, 1990) and thrive at temperatures up to 110 "C, the highest temperature known to be compatible with life.…”

mentioning

confidence: 99%

Response of Rubredoxin from Pyrococcus furiosus to Environmental Changes: Implications for the Origin of Hyperthermostability

Cavagnero¹,

Zhou²,

Adams³

et al. 1995

Biochemistry

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The bases of the hyperthennostability of rubredoxin from Py~ococcus furiosus (RdPf) have been probed by structural perturbations induced by solution pH and ionic strength changes. Comparison of the solution behavior at pH 7 and pH 2, as probed by far-and near-UV circular dichroism, Trp fluorescence emission, 1 -anilinonaphthalene-8-sulfonate (ANS) binding, and NMR spectroscopy, reveals the presence of only minimal structural variations at room temperature. At pH 2, the protein displays a surprising nearly native-like behavior at high ionic strength while, at low ionic strength, it is capable of strongly binding the hydrophobic probe ANS. All the secondary and tertiary structural features, including the environment of the hydrophobic core, appear to be intact regardless of pH and ionic strength. The apparent "melting" or denaturation temperature at pH 2, however, is 42 "C lower than at pH 7. This is attributed to the perturbation of many electrostatic interactions, including the disruption of all the ion pairs, which is complete at pH 2, as indicated by electrometric pH titrations. The implications of these findings for the origins of the hyperthennostability of rubredoxin are discussed.The existence of life forms that live at elevated temperature and pressure is an open manifestation of nature's ingenuity in managing to support life even under the most adverse conditions. A variety of so-called hyperthermophilic microorganisms have been isolated in recent years (Stetter et al., 1990;Adams, 1990;Stetter, 1986) in the vicinity of both terrestrial and submarine hydrothermal vents. The majority of them are classified as Archaea (Woese et al., 1990) and thrive at temperatures up to 110 "C, the highest temperature known to be compatible with life. They are also the most slowly evolving or "primitive" of known organisms. Little is known of the novel biochemistry that must be required to sustain life above 100 "C. However, the quest for biomolecules displaying unusual and interesting physicochemical properties has recently led to the discovery and isolation of specific enzymes from these hyperthermophilic organisms. Among those that have been purified so far are proteases (Eggen et al., 1990;Cowan et al., 1987), redox proteins (Aono et al., 1989;Blake et al., 1991), hydrogenases Juszczak et al., 1991;Pihl & Maier, 1991), dehydrogenases (Robb et al., 1992), ferredoxin-dependent oxidoreductases (Mukund & Adams, 1990), DNA polymerases (Lundberg et al., 1991), and enzymes involved in carbohydrate metabolism (Koch & Zablowski, 1990;Constantino et al., 1990). These enzymes are composed of the regular 20 amino acids and display a thermal stability unknown to their mesophilic counterparts. Yet, sequence comparisons reveal no apparent striking differences. At this juncture, the origin of protein hyperthermostability (Flam, * To whom correspondence should be addressed.

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“…Because of the frequent isolation of Archaea from these habitats it was assumed that Archaea dominate these communities (Stetter et al, 1990 ;Baross & Deming, 1995). The first cultivation-independent support for that hypothesis came from the analysis of lipids extracted from sulfide structures of a black smoker (Hedrick et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Relative abundance of Archaea and Bacteria along a thermal gradient of a shallow-water hydrothermal vent quantified by rRNA slot-blot hybridization

et al. 2000

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Slot-blot hybridization of rRNA with domain-specific oligonucleotide probes targeting the 16S rRNA of Archaea and Bacteria was utilized to assess the relative abundance of these domains along a thermal gradient at a shallow submarine hydrothermal vent near Milos Island (Greece). The highest prokaryotic rRNA concentrations (defined as the sum of bacterial and archaeal rRNA) were found in the uppermost sediment surface (0-20 mm), decreasing strongly with depth. This indicates that the microbial activity was mainly occurring in the surface layer of this hydrothermal vent. Furthermore, rRNA concentrations were higher in regions closer to the vent, suggesting that the hydrothermal activity stimulated microbial activity. Archaea seemed to be a minor component of the microbial community at this vent site, even in the zones with higher temperatures. Bacteria made up at least 78 % (mean 95 %) of the prokaryotic rRNA. However, along the steepest temperature gradient, the proportion of archaeal rRNA increased. Nevertheless, even in the hottest sediment layer where a quantification was possible (in situ temperature 82 SC) archaeal rRNA made up only 11 9 % of the prokaryotic rRNA. This suggests that Archaea were generally of minor importance at this vent site and were probably restricted to a narrow niche. The factors that allow Bacteria to dominate in a high temperature environment that was once believed to be the realm of Archaea remain elusive.

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Hyperthermophilic microorganisms

Cited by 364 publications

References 37 publications

The denaturation and degradation of stable enzymes at high temperatures

The denaturation and degradation of stable enzymes at high temperatures

Response of Rubredoxin from Pyrococcus furiosus to Environmental Changes: Implications for the Origin of Hyperthermostability

Relative abundance of Archaea and Bacteria along a thermal gradient of a shallow-water hydrothermal vent quantified by rRNA slot-blot hybridization

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