Studies of Sulfate Utilization of Algae: 15. Enzymes of Assimilatory Sulfate Reduction in Euglena and Their Cellular Localization

Brunold, Christian; Schiff, Jerome A. (1976). Studies of Sulfate Utilization of Algae: 15. Enzymes of Assimilatory Sulfate Reduction in Euglena and Their Cellular Localization. Plant Physiology, 57(3), pp. 430-436. American Society of Plant Physiologists 10.1104/pp.57.3.430

[img] Text
1976_PlantPhysiol_57_430.pdf - Published Version
Restricted to registered users only
Available under License Publisher holds Copyright.

Download (1MB) | Request a copy

Crude extracts of wild-type Euglena grown in the light (WTL) or in the dark (WTD) and a mutant lacking detectable plastid DNA (W3BUL) contain adenosine 5′-phosphosulfate (APS) sulfotransferase. Isotope dilution experiments indicate that adenosine 3′-phosphate 5′-phosphosulfate (PAPS) sulfotransferase is absent. Thiosulfonate reductase, requiring addition of NADH or NADPH but not ferredoxin, and O-acetyl-l-serine sulfhydrylase, the two other enzymes of the bound intermediate pathway of assimilatory sulfate reduction, are also present. Increasing levels of all three enzymes were found in WTL, WTD, and W3BUL during logarithmic growth but the various activities were similar at comparable stages of growth in all three types of cell. These results show that the three enzymes are not coded in the chloroplast DNA and are not restricted to Euglena cells having fully developed chloroplasts. Consistent with this, they do not increase during light-induced chloroplast development in resting cells and are found to be enriched in the mitochondrial fraction. Further resolution of this fraction on sucrose gradients shows that the APS sulfotransferase is associated with both the microbody (glyoxysomal) and mitochondrial fractions while the thiosulfonate reductase and O-acetyl-l-serine sulfhydrylase are associated only with the mitochondria. Thus the three known enzymes of the bound pathway of assimilatory sulfate reduction are present in Euglena mitochondria. Although the activity of the entire bound pathway (APS to cysteine) is low in extracts, addition of dithiothreitol which releases free sulfite from the product of the APS sulfotransferase reaction, causes an increase in reduction activity indicating that a sulfite reductase is also present. It remains to be shown which reducing system is the significant one in vivo in Euglena.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Stress Physiology (discontinued)
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Brunold, Christian

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0032-0889

Publisher:

American Society of Plant Physiologists

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

13 Jun 2018 17:49

Last Modified:

24 Oct 2019 08:07

Publisher DOI:

10.1104/pp.57.3.430

BORIS DOI:

10.7892/boris.107367

URI:

https://boris.unibe.ch/id/eprint/107367

Actions (login required)

Edit item Edit item
Provide Feedback