LOCALIZATION OFS-ADENOSYLMETHIONINE INCANDIDA UTILISBY ULTRAVIOLET MICROSCOPY

Abstract

Supplementation of the culture medium of Candida utilis (Torulopsis utilis) and of Saccharomyces cerevisiae with L-methionine results in greatly increased formation and accumulation of S-adenosylmethionine (Schlenk and DePalma, 1957a), a sulfonium compound whose structure comprises adenosine and methionine in the following way: Adenine-ribose-S-CH2 CH2 CH(NH2) C OOH &H3 Under suitable conditions, a concentration of 40 to 60 Amoles per gram of yeast cells on a dry weight basis may be obtained. Because the molecular weight of the sulfonium ion is 399, this corresponds to a concentration of 1.6 to 2.4 per cent. S-Adenosylmethionine has the typical absorption spectrum of an adenosine compound with Em 15,400 at 260 m,u. Its concentration remains essentially constant after growth and metabolism have ceased and the quantity of nucleic acids has declined. It appeared possible, therefore, to determine the location of S-adenosylmethionine within the cells by ultraviolet microscopy. As a preliminary to the optical studies and for correlation, the earlier chemical studies had to be amplified. The present report is a detailed account of our observations which have been summarized earlier (Svihla and Schlenk, 1958). MATERIALS AND METHODS Candida utilis (Torulopsis utilis) strain ATCC 9950 was used in the present experiments. The composition of the growth medium, culture conditions, and harvesting procedure have been described earlier (Schlenk and DePalma, 1957b). L-Methionine in a concentration of 4 to 6 ,umoles per ml, or a combination of S-methyl-L-methionine and L-homocysteine (4 ,umoles of each) was used as organic sulfur supplement. For

Ultraviolet Microscopy ofCandida albicans

“…Of unusual interest was the amount of adenosylmethionine found in strain 10259 when cultured under nonsupplemented conditions. It was almost as much as that obtained in early experiments with C. utilis when methionine was used as a sulfur supplement (18).…”

“…Svihla and Schlenk (18) demonstrated that the presence of sulfur amino acids in a growth medium can inhibit the growth of S. cerevisiae and C. utilis. Supplementation of the growth medium with sulfur amino acids also inhibited the growth of C. albicans.…”

“…Ultraviolet microscopy has been used to show that Candida utilis and Saccharomyces cerevisiae can accumulate S-adenosylmethionine in their vacuoles, when the yeasts are cultured in a medium supplemented with methionine and related amino acid (18,19).…”

LOCALIZATION OF CYTOPLASMIC NUCLEIC ACID DURING GROWTH AND ENCYSTMENT OF ENTAMOEBA INVADENS

“…The convincing demonstrations by Svihla and co-workers (26)(27)(28) that the ultraviolet microscope can be of considerable use in locating and following the fate of ultraviolet-absorbing substances in living cells provided impetus for the present study. The ability to measure ribonucleoprotein in the chromatoid bodies of living cells has enabled us to draw a much more precise picture of the changes in the concentration of RNA in the cells than has hitherto been possible.…”

Role of S -Adenosylmethionine in Methionine Biosynthesis in Yeast

“…Unlike most other microorganisms, yeasts accumulate large quantities of S-adenosylmethionine (7,18,21) when grown in the presence of methionine. The enzyme S-adenosylmethionine synthetase is present in yeast even when grown without exogenous methionine (16).…”