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Summary The RNA from zinc sufficient (+Zn) and deficient (−Zn) E. gracilis have been isolated and the three major RNA classes separated by affinity chromatography on oligo-(dT) and DBAE celluloses. The total RNA content and the ribosomal and transfer RNA fractions are the same in (+Zn) and (−Zn) cells. In (−Zn) cells, the messenger RNA fraction doubles and its base composition is altered, resulting in a two-fold increase in the G+C/A+U ratio. We have examined the role of Mn in determining these changes in RNA, since the intracellular content of this metal increases in (−Zn) cells. Increasing the Mn (II) content from 2 to 10 mM in assays with RNA polymerase from (−Zn) cells increases the incorporation of GMP relative to UMP from 1.0 to 3.5. Further, the ratios of CMP/GMP incorporation are 1.0, 2.2 and 1.2 in assays with 2, 5, 10 mM Mn (II), respectively. Thus, Mn (II) concentration can significantly alter function of RNA polymerase from (−Zn) E. gracilis cells.

The three major RNA classes from zinc-sufficient [(+Zn)] and zinc-deficient [(=Zn)] Euglena gracilis have been separated by affinity chromatography on oligo(dT)- and N-[N'-[m-(dihydroxyboryl)phenyl]succinamoyl]aminoethyl (DBAE)-celluloses. The total RNA content and the ribosomal and transfer RNA fractions are the same in (+Zn) and (=Zn) cells. IN (-Zn) cells, the messenger RNA fraction increases, and its altered base composition reveals additional bases and a 2-fold increase in the (G+C)/(A+U) ratio. Since the intracellular content of manganese increases in (-Zn) cells, we have examined its role in determining these changes in RNA composition. An increase in the Mn2+ content from 1 to 10 mM in assays with RNA polymerases I and II from (+Zn) cells and those with the single RNA polymerase from (-Zn) cells decreases the ratio of UMP to CMP incorporated from 1.7 to 1.0, 2.1 to 0.8 and 3.5 to 0.4, respectively. Thus, Mn2+ concentration can significantly alter the products of the enzymatic action of RNA polymerases from both (+Zn) and (-Zn) E. gracilis cells.

The purine and pyrimidine bases of E. gracilis have been separated using a high-pressure liquid chromatograph (HPLC). Each base was unambiguously identified by its characteristic elution profile and UV absorption spectrum. This method allows for the study of the base composition of mRNAs altered by pathological processes, exemplified here by the analysis and comparison of mRNAs from zinc sufficient and deficient organisms.