Bericht der Central-Abtheilung über den Gesetz-Entwurf wegen der Verpflichtung der Gemeinden zum Ersatze des bei öffentlichen Aufläufen verursachten Schadens, sowie über den durch den Abgeordneten Krackrügge von Erfurt auf Erlassung eines derartigen Gesetzes gerichteten Antrag: Am 5. Juni d. J. beantragte der Abgeordnete Krackrügge aus Erfurt ...

Welsch (Projektbearbeiter): Ablehnung sowohl des ministeriellen als auch des Krackrüggeschen Gesetzentwurfes in der vorliegenden Form und dessen Neuformulierung mit nur geringfügigen Änderungen. Samt ausführlich(st)er Darlegung der Beweggründe und des Entscheidungsfindungsprozesses

Bericht der Kommission zur Untersuchung der Posener Angelegenheiten über die derselben überwiesenen, den Belagerungs-Zustand von Posen betreffenden, Vorlagen des Staatsministeriums: In der 67sten Sitzung der National-Versammlung (5. Oktober d. J.) richtete der Abgeordnete von Pokrzywnicki ...

Welsch (Projektbearbeiter): Die Kommission spricht sich gegen die Fortdauer des Belagerungszustandes über Stadt und Festung Posen aus, da die Sicherheit der Festung davon nicht abhängig sei

Plant Adenosine 5′-phosphosulfate Reductase Is a Novel Iron-Sulfur Protein

Adenosine 5′-phosphosulfate reductase (APR) catalyzes the two-electron reduction of adenosine 5′-phosphosulfate to sulfite and AMP, which represents the key step of sulfate assimilation in higher plants. Recombinant APRs from both Lemna minorand Arabidopsis thaliana were overexpressed inEscherichia coli and isolated as yellow-brown proteins. UV-visible spectra of these recombinant proteins indicated the presence of iron-sulfur centers, whereas flavin was absent. This result was confirmed by quantitative analysis of iron and acid-labile sulfide, suggesting a 4Fe-4S cluster as the cofactor. EPR spectroscopy of freshly purified enzyme showed, however, only a minor signal at g = 2.01. Therefore, Mössbauer spectra of 57Fe-enriched APR were obtained at 4.2 K in magnetic fields of up to 7 tesla, which were assigned to a diamagnetic 4Fe-4S2+ cluster. This cluster was unusual because only three of the iron sites exhibited the same Mössbauer parameters. The fourth iron site gave, because of the bistability of the fit, a significantly smaller isomer shift or larger quadrupole splitting than the other three sites. Thus, plant assimilatory APR represents a novel type of adenosine 5′-phosphosulfate reductase with a 4Fe-4S center as the sole cofactor, which is clearly different from the dissimilatory adenosine 5′-phosphosulfate reductases found in sulfate reducing bacteria.

Sulfate assimilation in higher plants. Characterization of a stable intermediate in the adenosine 5′-phosphosulfate reductase reaction

The enzyme catalysing the reduction of adenosine 5′-phosphosulfate (AdoPS) to sulfite in higher plants, AdoPS reductase, is considered to be the key enzyme of assimilatory sulfate reduction. In order to address its reaction mechanism, the APR2 isoform of this enzyme from Arabidopsis thaliana was overexpressed in Escherichia coli and purified to homogeneity. Incubation of the enzyme with [35S]AdoPS at 4 °C resulted in radioactive labelling of the protein. Analysis of APR2 tryptic peptides revealed 35SO2–3 bound to Cys248, the only Cys conserved between AdoPS and prokaryotic phosphoadenosine 5′-phosphosulfate reductases. Consistent with this result, radioactivity could be released from the protein by incubation with thiols, inorganic sulfide and sulfite. The intermediate remained stable, however, after incubation with sulfate, oxidized glutathione or AdoPS. Because truncated APR2, missing the thioredoxin-like C-terminal part, could be labelled even at 37 °C, and because this intermediate was more stable than the complete protein, we conclude that the thioredoxin-like domain was required to release the bound SO2–3 from the intermediate. Taken together, these results demonstrate for the first time the binding of 35SO2–3 from [35S]AdoPS to AdoPS reductase and its subsequent release, and thus contribute to our understanding of the molecular mechanism of AdoPS reduction in plants.