Protze, Jonas ; Müller, Fabian ; Lauber, Karin ; Naß, Bastian ; Mentele, Reinhard ; Lottspeich, Friedrich ; Kletzin, Arnulf (2011)
An extracellular tetrathionate hydrolase from the thermoacidophilic archaeon Acidianus ambivalens with an activity optimum at pH 1.
In: Frontiers in microbial physiology and metabolism, 2 (68)
doi: 10.3389/fmicb.2011.00068
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Background: The thermoacidophilic and chemolithotrophic archaeon Acidianus ambivalens is routinely grown with sulfur and CO2-enriched air. We had described a membrane-bound, tetrathionate (TT) forming thiosulfate:quinone oxidoreductase. Here we describe the first TT hydrolase (TTH) from Archaea. Results: A. ambivalens cells grown aerobically with TT as sole sulfur source showed doubling times of 9 h and final cell densities of up to 8 × 108/ml. TTH activity (≈0.28 U/mg protein) was found in cell-free extracts of TT-grown but not of sulfur-grown cells. Differential fractionation of freshly harvested cells involving a pH shock showed that about 92% of the TTH activity was located in the pseudo-periplasmic fraction associated with the surface layer, while 7.3% and 0.3% were present in the soluble and membrane fractions, respectively. The enzyme was enriched 54-fold from the cytoplasmic fraction and 2.1-fold from the pseudo-periplasmic fraction. The molecular mass of the single subunit was 54 kDa. The optimal activity was at or above 95°C at pH 1. Neither PQQ nor divalent cations had a significant effect on activity. The gene (tth1) was identified following N-terminal sequencing of the protein. Northern hybridization showed that tth1 was transcribed in TT-grown cells in contrast to a second paralogous tth2 gene. The deduced amino acid sequences showed similarity to the TTH from Acidithiobacillus and other proteins from the PQQ dehydrogenase superfamily. It displayed a β-propeller structure when being modeled, however, important residues from the PQQ-binding site were absent. Conclusion: The soluble, extracellular, and acidophilic TTH identified in TT-grown A. ambivalens cells is essential for TT metabolism during growth but not for the downstream processing of the TQO reaction products in S°-grown cells. The liberation of TTH by pH shock from otherwise intact cells strongly supports the pseudo-periplasm hypothesis of the S-layer of Archaea.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2011 |
| Autor(en): | Protze, Jonas ; Müller, Fabian ; Lauber, Karin ; Naß, Bastian ; Mentele, Reinhard ; Lottspeich, Friedrich ; Kletzin, Arnulf |
| Art des Eintrags: | Bibliographie |
| Titel: | An extracellular tetrathionate hydrolase from the thermoacidophilic archaeon Acidianus ambivalens with an activity optimum at pH 1 |
| Sprache: | Englisch |
| Publikationsjahr: | 2011 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Frontiers in microbial physiology and metabolism |
| Jahrgang/Volume einer Zeitschrift: | 2 |
| (Heft-)Nummer: | 68 |
| DOI: | 10.3389/fmicb.2011.00068 |
| URL / URN: | https://www.frontiersin.org/articles/10.3389/fmicb.2011.0006... |
| Kurzbeschreibung (Abstract): | Background: The thermoacidophilic and chemolithotrophic archaeon Acidianus ambivalens is routinely grown with sulfur and CO2-enriched air. We had described a membrane-bound, tetrathionate (TT) forming thiosulfate:quinone oxidoreductase. Here we describe the first TT hydrolase (TTH) from Archaea. Results: A. ambivalens cells grown aerobically with TT as sole sulfur source showed doubling times of 9 h and final cell densities of up to 8 × 108/ml. TTH activity (≈0.28 U/mg protein) was found in cell-free extracts of TT-grown but not of sulfur-grown cells. Differential fractionation of freshly harvested cells involving a pH shock showed that about 92% of the TTH activity was located in the pseudo-periplasmic fraction associated with the surface layer, while 7.3% and 0.3% were present in the soluble and membrane fractions, respectively. The enzyme was enriched 54-fold from the cytoplasmic fraction and 2.1-fold from the pseudo-periplasmic fraction. The molecular mass of the single subunit was 54 kDa. The optimal activity was at or above 95°C at pH 1. Neither PQQ nor divalent cations had a significant effect on activity. The gene (tth1) was identified following N-terminal sequencing of the protein. Northern hybridization showed that tth1 was transcribed in TT-grown cells in contrast to a second paralogous tth2 gene. The deduced amino acid sequences showed similarity to the TTH from Acidithiobacillus and other proteins from the PQQ dehydrogenase superfamily. It displayed a β-propeller structure when being modeled, however, important residues from the PQQ-binding site were absent. Conclusion: The soluble, extracellular, and acidophilic TTH identified in TT-grown A. ambivalens cells is essential for TT metabolism during growth but not for the downstream processing of the TQO reaction products in S°-grown cells. The liberation of TTH by pH shock from otherwise intact cells strongly supports the pseudo-periplasm hypothesis of the S-layer of Archaea. |
| Fachbereich(e)/-gebiet(e): | 10 Fachbereich Biologie ?? fb10_mikrobiologie ?? 10 Fachbereich Biologie > Sulfur Biochemistry and Microbial Bioenergetics |
| Hinterlegungsdatum: | 25 Mai 2011 08:38 |
| Letzte Änderung: | 23 Nov 2020 07:38 |
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