AMP-Forming Acetyl Coenzyme A Synthetase in the Outermost Membrane of the Hyperthermophilic Crenarchaeon Ignicoccus hospitalis

Mayer, Florian; Küper, Ulf; Meyer, Carolin; Daxer, Stefanie; Müller, Volker; Rachel, Reinhard; Huber, Harald

doi:10.1128/jb.06130-11

Cited by 27 publications

(23 citation statements)

References 72 publications

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“…Recently, it was shown that the ATP-consuming reaction of ACS could be coupled to ATP-producing processes, a possibility that gives interesting perspectives regarding further research on anammox carbon metabolism (Mayer et al 2012). …”

Section: Resultsmentioning

confidence: 99%

Genome analysis and heterologous expression of acetate-activating enzymes in the anammox bacterium Kuenenia stuttgartiensis

et al. 2012

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Anaerobic ammonium-oxidizing bacteria were recently shown to use short-chain organic acids as additional energy source. The AMP-forming acetyl-CoA synthetase gene (acs) of Kuenenia stuttgartiensis, encoding an important enzyme involved in the conversion of these organic acids, was identified and heterologously expressed in Escherichia coli to investigate the activation of several substrates, that is, acetate, propionate and butyrate. The heterologously expressed ACS enzyme could complement an E. coli triple mutant deficient in all pathways of acetate activation. Activity was observed toward several short-chain organic acids, but was highest with acetate. These properties are in line with a mixotrophic growth of anammox bacteria. In addition to acs, the genome of K. stuttgartiensis contained the essential genes of an acetyl-CoA synthase/CO dehydrogenase complex and genes putatively encoding two isoenzymes of archaeal-like ADP-forming acetyl-CoA synthetase underlining the importance of acetyl-CoA as intermediate in the carbon assimilation metabolism of anammox bacteria.Electronic supplementary materialThe online version of this article (doi:10.1007/s00203-012-0829-7) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Genome analysis and heterologous expression of acetate-activating enzymes in the anammox bacterium Kuenenia stuttgartiensis

et al. 2012

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“…acetate, succinate) are possible. One such reaction could be already confirmed (Mayer et al 2012): In the presence of acetate, acetyl-CoA is formed in a one-step mechanism via an AMP-forming acetyl-CoA synthetase (ACS). This enzyme was identified to be also located at the OCM of I. hospitalis (Fig.…”

Section: Energy Conservationmentioning

confidence: 95%

“…Therefore, it can be concluded that in I. islandicus and I. pacificus the OCM is energized. Furthermore, the acetyl-CoA synthesis of all members of the genus Ignicoccus is associated with the OCM (Mayer et al 2012), demonstrating that the extraordinary location of these enzymes or enzyme complexes is a common feature of all members the genus Ignicoccus. In contrast, the pore-forming complex Ihomp1 is exclusively found on the cell surface of I. hospitalis.…”

Section: Situation In Other Ignicoccus Speciesmentioning

confidence: 98%

The unusual cell biology of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis

Huber¹,

Küper

Daxer³

et al. 2012

Antonie van Leeuwenhoek

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The Crenarchaeon Ignicoccus hospitalis is an anaerobic, obligate chemolithoautotrophic hyperthermophile, growing by reduction of elemental sulfur using molecular hydrogen as electron donor. Together with Nanoarchaeum equitans it forms a unique, archaeal biocoenosis, in which I. hospitalis serves as host for N. equitans. Both organisms can be cultivated in a stable coculture which is mandatory for N. equitans but not for I. hospitalis. This strong dependence is affirmed by the fact that N. equitans obtains its lipids and amino acids from the host. I. hospitalis cells exhibit several unique features: they can adhere to surfaces by extracellular appendages ('fibers') which are not used for motility; they use a novel CO(2) fixation pathway, the dicarboxylate/4-hydroxybutyrate pathway; and they exhibit a unique cell envelope for Archaea consisting of two membranes but lacking an S-layer. These membranes form two cell compartments, a tightly packed cytoplasm surrounded by a weakly staining intermembrane compartment (IMC) with a variable width from 20 to 1,000 nm. In this IMC, many round or elongated vesicles are found which may function as carriers of lipids or proteins out of the cytoplasm. Based on immuno-EM analyses and immuno-fluorescence experiments it was demonstrated recently that the A(1)A(O) ATP synthase, the H(2):sulfur oxidoreductase complex and the acetyl-CoA synthetase (ACS) of I. hospitalis are located in its outermost membrane. Therefore, this membrane is energized and is here renamed as "outer cellular membrane" (OCM). Among all prokaryotes possessing two membranes in their cell envelope, I. hospitalis is the first organism with an energized outermost membrane and ATP synthesis outside the cytoplasm. Since DNA and ribosomes are localized in the cytoplasm, energy conservation is separated from information processing and protein biosynthesis in I. hospitalis. This raises questions concerning the function and characterization of the two membranes, the two cell compartments and of a possible ATP transfer to N. equitans.

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“…Recent characterizations of two acetyl-CoA synthetases (ACS) from Ignicoccus hospitalis [26] and Pyrobaculum aerophilum [27] have uncovered novel structural adaptations, namely, a difference in oligomeric state from that of the mesophilic variants. Compared to their mesophilic counterparts, these hyperthermophilic enzymes form octomers whereas the aforementioned mesophiles follow the general trend of being monomers or homodimers.…”

Section: Thermophilic Proteinsmentioning

confidence: 99%

Protein Adaptations in Archaeal Extremophiles

Reed

Lewis

Trejo

et al. 2013

Archaea

248

174

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Extremophiles, especially those in Archaea, have a myriad of adaptations that keep their cellular proteins stable and active under the extreme conditions in which they live. Rather than having one basic set of adaptations that works for all environments, Archaea have evolved separate protein features that are customized for each environment. We categorized the Archaea into three general groups to describe what is known about their protein adaptations: thermophilic, psychrophilic, and halophilic. Thermophilic proteins tend to have a prominent hydrophobic core and increased electrostatic interactions to maintain activity at high temperatures. Psychrophilic proteins have a reduced hydrophobic core and a less charged protein surface to maintain flexibility and activity under cold temperatures. Halophilic proteins are characterized by increased negative surface charge due to increased acidic amino acid content and peptide insertions, which compensates for the extreme ionic conditions. While acidophiles, alkaliphiles, and piezophiles are their own class of Archaea, their protein adaptations toward pH and pressure are less discernible. By understanding the protein adaptations used by archaeal extremophiles, we hope to be able to engineer and utilize proteins for industrial, environmental, and biotechnological applications where function in extreme conditions is required for activity.

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AMP-Forming Acetyl Coenzyme A Synthetase in the Outermost Membrane of the Hyperthermophilic Crenarchaeon Ignicoccus hospitalis

Cited by 27 publications

References 72 publications

Genome analysis and heterologous expression of acetate-activating enzymes in the anammox bacterium Kuenenia stuttgartiensis

Genome analysis and heterologous expression of acetate-activating enzymes in the anammox bacterium Kuenenia stuttgartiensis

The unusual cell biology of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis

Protein Adaptations in Archaeal Extremophiles

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