Peroxisomes of alkane‐utilizing yeasts metabolic functions and practical aspects

Abstract

One of the most striking features of alkane-grown yeast cells is conspicuous appearance of peroxisomes in harmony with a high level of ciltalase. This unique phenomenon was first demonstrated in the authors' laboratory, and the metabolic functions of peroxisomes in yeasts utilizing alkmes has been established with intact peroxisomes isolated by density gradient centrifugation. The organelles participate in the degradation of fatty acids derived from alkanes to C,-units and the synthesis of gluconeogenic intermediates from C,-units. The abundant appearance of peroxisomes in alkane-utilizing cells has allowed successful production of several useful enzymes including catalase, D-amino acid oxidase, uricase, acyl-CoA oxidnse etc. Yeast cells will be an excellent system for investigeting the functions and development of peroxisomes because biogenesis of the organelles is induced only by transferring the cells into alkane medium from glucose or ethanol medium. ZusammenfassungAuf Alkan gewachsene Hefezellen zeigen ah typisches Merkmal ein ventarktes Auftreten von Peroxisomen und damit verbunden einen hohen Katalasespiegel. Dies wurde erstmals durch Laboruntersuchungen des Autors gezeigt ; die metabolischen Funktionen der Peroxisomen in alkanverwertenden Hefen konnten an durch Dichtegradientenzentrifugation gewonnenen intakten Peroxisomen untersucht werden. Diese Organellen sind am Katabolismus der Fettsiiuren, die beim Abbau der Alkane zu C,-Kiirpern entstehen, und an der Synthese gluconeogenetischen Intermediaten aus C,-KOrpern beteiligt. Das verstarkte Auftreten der Peroxisomen in alkanverwertenden Zellen hat eine erfolgreiche Produktion verschiedener biotechnologisch interessanter Enzyme, wie Katalase, D-Aminoaiiure-Oxidase, Uricase, Acyl-CoA-Oxidase usw. ermiiglicht. Hefezellen werden zunehmend als giinstige Organismen zur Untersuchung der Funktionen und der Entwicklung von Peroxisomen herangezogen, weil ihre Biogenese allein durch einen Substratwechsel (uberfiihren der Zellen aus Glucoseoder Ethanol-Medium in ein Alkan-Medium) induziert werden kann.

Physiology of aliphatic hydrocarbon-degrading microorganisms

“…81 bon utilisation rather than an adaptation for uptake. Such structures are exemplified by microbodies in alkane-grown yeasts which are structures rich in oxidative enzymes (Fukui & Tanaka 1979). Indeed, Hommel & Ratledge (1990) showed that the fatty alcohol oxidases involved in n-alkane metabolism by Candida bombicola were solely present in the microsomal fraction.…”

Biogenesis and metabolic significance of microbodies in urate-utilizing yeasts

“…Previous studies have demonstrated that as in microorganisms that can use uric acid as a carbon source (Vogels and Van der Drift, 1976), urate oxidase was the key enzyme involved in urate metabolism in yeasts. In the latter organism this enzyme is present in peroxisomes which developed in small numbers during growth of various yeast species in media containing uric acid as a nitrogen source (Fukui and Tanaka, 1979;Veenhuis et al, 1983b;Veenhuis and Harder, 1985).…”

Pichia pastoris as a host system for transformations.

“…Recently, it was shown that control of AO expression in P. pastoris is substantially transcriptional (17). A second point of interest in methylotrophic yeasts is the mechanism by which enzymes such as AO and catalase are compartmentalized in peroxisomes (18). Peroxisomal packaging of AO does not appear to involve a processed amino-terminal signal sequence (17).…”