Abstract
BackgroundThe yeast Xanthophyllomyces dendrorhous is used for the microbiological production of the antioxidant carotenoid astaxanthin. In this study, we established an optimal protocol for protein extraction and performed the first proteomic analysis of the strain ATCC 24230. Protein profiles before and during the induction of carotenogenesis were determined by two-dimensional polyacrylamide gel electrophoresis and proteins were identified by mass spectrometry.ResultsAmong the approximately 600 observed protein spots, 131 non-redundant proteins were identified. Proteomic analyses allowed us to identify 50 differentially expressed proteins that fall into several classes with distinct expression patterns. These analyses demonstrated that enzymes related to acetyl-CoA synthesis were more abundant prior to carotenogenesis. Later, redox- and stress-related proteins were up-regulated during the induction of carotenogenesis. For the carotenoid biosynthetic enzymes mevalonate kinase and phytoene/squalene synthase, we observed higher abundance during induction and/or accumulation of carotenoids. In addition, classical antioxidant enzymes, such as catalase, glutathione peroxidase and the cytosolic superoxide dismutases, were not identified.ConclusionsOur results provide an overview of potentially important carotenogenesis-related proteins, among which are proteins involved in carbohydrate and lipid biosynthetic pathways as well as several redox- and stress-related proteins. In addition, these results might indicate that X. dendrorhous accumulates astaxanthin under aerobic conditions to scavenge the reactive oxygen species (ROS) generated during metabolism.
Highlights
The yeast Xanthophyllomyces dendrorhous is used for the microbiological production of the antioxidant carotenoid astaxanthin
Isolation of soluble proteins and 2D electrophoresis The aim of the present study was to characterize the proteome of soluble protein extracts of the yeast X. dendrorhous grown in MM-glucose media
In this work, which is the first proteomic characterization of X. dendrorhous, we describe a protocol for the enrichment of protein extracts for membrane-bound proteins and the efficient extraction of proteins in the presence of excess hydrophobic materials such as lipids or carotenoids
Summary
The yeast Xanthophyllomyces dendrorhous is used for the microbiological production of the antioxidant carotenoid astaxanthin. The basidiomycete Xanthophyllomyces dendrorhous (formerly known as Phaffia rhodozyma) is an excellent astaxanthin-producing yeast and has been regarded as one of the most promising microorganisms for the commercial production of this carotenoid [1,2]. Astaxanthin is a pigment that produces the characteristic coloration of some birds, crustaceans and salmon. It has been used as a feed and food pigment in the aquaculture industry and has been evaluated as a pharmaceutical component because it may possess antioxidant activity [3,4]. The condensation of two molecules of GGPP is catalyzed by the bifunctional enzyme phytoene synthase to produce phytoene (C40). B-carotene is oxidized by astaxanthin synthetase to yield astaxanthin [15]
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