Kinetics of the intracellular availability of heme after supplementing a heme-deficient yeast mutant with 5-aminolevulinate.

The 5-aminolevulinic acid synthetase-deficient yeast mutant ole3 (Bard, M., Woods, R.A. & Haslam, J.M. (1974) Biochem. Biophys. Res. Commun. 56, 324-330), pregrown in a 5-aminolevulinic acid containing medium, can grow on glucose or galactose medium in the absence of heme for about 13 generations. When supplemented with 5-aminolevulinate before their 9th cell division, the cells can be induced to full respiratory competence. From the measurement of heme-dependent parameters (e.g. respiration, transcription of iso-1-cytochrome c mRNA and the post-translational proteolytic processing of the heme-free intermediate precursor of cytochrome c1 to its heme-containing mature form) it can be judged that heme is available in the cell about one hour after the addition of 5-aminolevulinate. The onset of respiration, however, does not occur to an appreciable extent before the 3rd hour of induction. The heme analogue deuteroporphyrin IX prevents respiratory adaptation but yet effects the transcription of heme-controlled genes.