Effect of Gabaculine on the Synthesis of Heme and Cytochrome f in Etiolated Wheat Seedlings

The effect of gabaculine (3-amino 2,3-dihydrobenzoic acid), an inhibitor of tetrapyrrole synthesis, on the accumulation of heme and cytochrome f in etiolated wheat (Triticum aestivum var Mardler) seedlings has been examined. Gabaculine treatment resulted in decreased amounts of heme and of holocytochrome f detected spectroscopically and by peroxidase activity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amount of the cytochrome f polypeptide detected immunochemically on Western blots was much less affected by gabaculine treatment, indicating that apocytochrome f synthesis was not tightly coupled to heme availability. Gabaculine treatment did not affect the size of the cytochrome f polypeptide, indicating that heme addition is not required for proteolytic removal of the presequence.