Metabolism of halophilic archaea

Falb, Michaela; Müller, Kerstin; Königsmaier, Lisa; Oberwinkler, Tanja; Horn, Patrick; Gronau, Susanne von; Gonzalez, Orland; Pfeiffer, Friedhelm; Bornberg‐Bauer, Erich; Oesterhelt, Dieter

doi:10.1007/s00792-008-0138-x

Cited by 209 publications

(230 citation statements)

References 111 publications

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“…Interestingly, the representatives of the genus Halobacterium possess only glutamate mutase and methylaspartate ammonia lyase genes, although the genes for other key enzymes of the methylaspartate cycle are missing. They probably use the corresponding enzymes for the utilization of glutamate (Falb et al, 2008). The genome analysis suggests that the usage of the methylaspartate cycle often correlates with the capability to synthesize polyhydroxyalkanoates, whereas the haloarchaea using the glyoxylate cycle are often incapable to synthesize this storage material ( Figure 6).…”

Section: Discussionmentioning

confidence: 99%

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

et al. 2015

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Haloarchaea (class Halobacteria) live in extremely halophilic conditions and evolved many unique metabolic features, which help them to adapt to their environment. The methylaspartate cycle, an anaplerotic acetate assimilation pathway recently proposed for Haloarcula marismortui, is one of these special adaptations. In this cycle, acetyl-CoA is oxidized to glyoxylate via methylaspartate as a characteristic intermediate. The following glyoxylate condensation with another molecule of acetylCoA yields malate, a starting substrate for anabolism. The proposal of the functioning of the cycle was based mainly on in vitro data, leaving several open questions concerning the enzymology involved and the occurrence of the cycle in halophilic archaea. Using gene deletion mutants of H. hispanica, enzyme assays and metabolite analysis, we now close these gaps by unambiguous identification of the genes encoding all characteristic enzymes of the cycle. Based on these results, we were able to perform a solid study of the distribution of the methylaspartate cycle and the alternative acetate assimilation strategy, the glyoxylate cycle, among haloarchaea. We found that both of these cycles are evenly distributed in haloarchaea. Interestingly, 83% of the species using the methylaspartate cycle possess also the genes for polyhydroxyalkanoate biosynthesis, whereas only 34% of the species with the glyoxylate cycle are capable to synthesize this storage compound. This finding suggests that the methylaspartate cycle is shaped for polyhydroxyalkanoate utilization during carbon starvation, whereas the glyoxylate cycle is probably adapted for growth on substrates metabolized via acetyl-CoA.

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Section: Discussionmentioning

confidence: 99%

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

et al. 2015

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“…This alternative pathway also appears to be present in other methanogens as well as in halophiles and might also be operative in other TKnegative organisms such as Arc. fulgidus (369).…”

Section: Transketolasementioning

confidence: 99%

Carbohydrate Metabolism in Archaea: Current Insights into Unusual Enzymes and Pathways and Their Regulation

Bräsen

Esser

Rauch

et al. 2014

Microbiol Mol Biol Rev

271

294

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SUMMARY The metabolism of Archaea , the third domain of life, resembles in its complexity those of Bacteria and lower Eukarya . However, this metabolic complexity in Archaea is accompanied by the absence of many “classical” pathways, particularly in central carbohydrate metabolism. Instead, Archaea are characterized by the presence of unique, modified variants of classical pathways such as the Embden-Meyerhof-Parnas (EMP) pathway and the Entner-Doudoroff (ED) pathway. The pentose phosphate pathway is only partly present (if at all), and pentose degradation also significantly differs from that known for bacterial model organisms. These modifications are accompanied by the invention of “new,” unusual enzymes which cause fundamental consequences for the underlying regulatory principles, and classical allosteric regulation sites well established in Bacteria and Eukarya are lost. The aim of this review is to present the current understanding of central carbohydrate metabolic pathways and their regulation in Archaea . In order to give an overview of their complexity, pathway modifications are discussed with respect to unusual archaeal biocatalysts, their structural and mechanistic characteristics, and their regulatory properties in comparison to their classic counterparts from Bacteria and Eukarya . Furthermore, an overview focusing on hexose metabolic, i.e., glycolytic as well as gluconeogenic, pathways identified in archaeal model organisms is given. Their energy gain is discussed, and new insights into different levels of regulation that have been observed so far, including the transcript and protein levels (e.g., gene regulation, known transcription regulators, and posttranslational modification via reversible protein phosphorylation), are presented.

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“…There are few studies focused on the metabolism of halophilic archaea, however most of them analyse this subject through systematic metabolic reconstruction and comparative analysis of available genomes (Falb et al, 2008). At the time of writing this chapter, when systems biology approaches have been used to construct predictive models of gene expression and metabolism in Bacteria and Eukarya, only few studies summarise details about the status of genomics, functional genomics, and molecular genetics of haloarchaea (Soppa et al, 2008).…”

Section: Denitrificationmentioning

confidence: 99%

Anaerobic Metabolism in Haloferax Genus

Torregrosa-Crespo

Martínez‐Espinosa

Esclapez

et al. 2016

Advances in Microbial Physiology

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A number of species of Haloferax genus (halophilic Archaea) are able to grow micro aerobically or even anaerobically using different alternative electron acceptors such as fumarate, nitrate, chlorate, dimethyl sulphoxide, sulphide and/or trimethylamine. This metabolic capability is also shown by other species of the Halobacteriaceae and Haloferacaceae families (Archaea domain) and it has been mainly tested by physiological studies where cells growth is observed under anaerobic conditions in the presence of the mentioned compounds. This work summarises the main reported features on anaerobic metabolism in the Haloferax, one of the better described haloarchaeal genus with significant potential uses in Biotechnology and Bioremediation. Special attention has been paid to denitrification, also called nitrate respiration. This pathway has been studied so far from KEY WORDSHaloarchaea, denitrification, anaerobic metabolism, Nox emissions, bioremediation.

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Metabolism of halophilic archaea

Cited by 209 publications

References 111 publications

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

Carbohydrate Metabolism in Archaea: Current Insights into Unusual Enzymes and Pathways and Their Regulation

Anaerobic Metabolism in Haloferax Genus

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