Studies of sulfate utilization by algae 14. Distribution of adenosine-3′-phosphate-5′-phosphosulfate (PAPS) and adenosine-5′-phosphosulfate (APS) sulfotransferases in assimilatory sulfate reducers

Abstract

Dissimilatory sulfate reducers have been shown to utilize adenosine 5′-phosphosulfate (APS) and it has been suggested that all assimilatory sulfate reducers use adenosine 3′-phosphate 5′-phosphosulfate (PAPS) as the immediate donor for reduction. With the finding that the assimilatory sulfate reducer Chlorella pyrenoidosa uses APS as the substrate for reduction via APS-sulfotransferase while Escherichia coli uses PAPS via a PAPS-sulfotransferase, this correlation does not appear to hold; thus a phylogenetic survey of APS and PAPS utilization by reducing systems has been undertaken in order to determine the significance of their distribution. It is shown that non-photosynthetic organisms such as E. coli among the procaryotes and yeast among the eucaryotes contain PAPS-sulfotransferase while photosynthetic organisms including the red algae, the brown algae, the diatoms, the dinoflagellates, the cryptophytes, the prasinophytes and the blue-green algae as well as spinach chloroplasts all utilize APS rather than PAPS. This suggests that APS utilization for assimilatory reduction is characteristic of chloroplasts and chloroplast-containing organisms while PAPS utilization for assimilatory reduction is characteristic of non-photosynthetic organisms. The evolutionary significance of this distribution is discussed.