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Heme synthesis in yeast does not require oxygen as an obligatory electron acceptor

100%

Krawiec Z., Swiecilo A., Bilinski T.

Acta Biochimica Polonica

2000

tom 47

nr 4

In a previous paper (Krawiec, Z., Bilinski, T., Schueller, C. & Ruis, H., 2000, Acta Biochim. Polon. 47, 201-207) we have shown that catalase T holoenzyme is synthesized in the absence of oxygen after treatment of anaerobic yeast cultures with 0.3M. NaCl, or during heat shock. This finding suggests that heme moiety of the enzyme can either be formed de novo in the absence of oxygen, or derives from the preexisting heme pool present in cells used as inoculum. The strain bearing hem1 mutation, resulting in inability to form delta-aminolevulinate (ALA), the first committed precursor of heme, was used in order to form heme-depleted cells used as inocula. The cultures were supplemented with ALA at the end of anaerobic growth prior the stress treatment. The appearance of active catalase T in the stressed cells strongly suggests that heme moiety of catalase T is formed in the absence of oxygen. This finding suggests the necessity to reconsider current opinions concerning mechanisms of heme synthesis and the role of heme as an oxygen sensor.

Reactive oxygen species as second messengers? Induction of the expression of yeast catalase T gene by heat and hyperosmotic stress does not require oxygen

80%

Krawiec Z., Bilinski T., Schuller C., Ruis H.

Acta Biochimica Polonica

2000

tom 47

nr 1

It is shown that oxygen is not absolutely needed for stress-induced synthesis of catalase T in the yeast Saccharomyces cerevisiae. Yeast cells develop heat resistance after exposure to elevated temperatures in anoxia. The levels of catalase activity and thermotolerance are comparable to those in aerobically stressed cells. While these results obviously do not exclude a stress signaling role of reactive oxygen species in some systems, as postulated by other authors, they suggest that the question of the obligatory requirement for reactive oxygen species in other stress signaling systems should be rigorously re-investigated.

Ograniczanie wyników

2 Acta Biochimica Polonica

2 Bilinski T.

2 Krawiec Z.

1 Ruis H.

1 Schuller C.

1 Swiecilo A.

2 2000

Wyniki wyszukiwania

Heme synthesis in yeast does not require oxygen as an obligatory electron acceptor

Reactive oxygen species as second messengers? Induction of the expression of yeast catalase T gene by heat and hyperosmotic stress does not require oxygen