Regulation of ornithine decarboxylase activity in Mucor bacilliformis and Mucor rouxii |
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| Institution: | 1. G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of Russian Academy of Sciences, Vladivostok 690022, Russia;2. Innovation-technology center, Far Eastern Federal University, Vladivostok 690950, Russia;3. Federal Scientific Centre of the East Asia Terrestrial Biodiversity, Far Eastern Branch of Russian Academy of Sciences, Vladivostok 690022, Russia;4. School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950, Russia |
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| Abstract: | Ornithine decarboxylase (ODC) from Mucor bacilliformis and Mucor rouxii was studied. Enzymatic activity was maximal at pH 7.2–7.4 and at 30°C. The Km was 0.17 mM for the M. bacilliformis enzyme. Putrescine was a competitive inhibitor of ODC with a Ki of 2–3 mM. Enzymatic activity was undetectable in sporangiospores but increased rapidly during the first stages of spore swelling, reaching the highest levels during germ tube or bud emergence, and then decreased. Incubation at 30°C inhibited spore germination in M. bacilliformis and prevented development of ODC activity. More ODC activity was present in mycelial than in yeast cells. Morphological transition of yeast cells into hyphae by an anaerobic-aerobic shift induced a rapid and transient increase in ODC activity. Similar results were obtained when the morphogenetic transformation of M. rouxii was induced by CO2 elimination in an anaerobic environment. Transfer of mycelial cells to anaerobiosis resulted in a rapid decrease in enzyme activity. Changes in ODC activity were accompanied by a change in the pool of polyamines. The possible role of ODC in growth and cell differentiation in Mucor is discussed. |
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