A Role for Sterol Levels in Oxygen Sensing in <i>Saccharomyces cerevisiae</i>

Davies, Brandon S.J.; Rine, Jasper

doi:10.1534/genetics.106.059964

Cited by 100 publications

(144 citation statements)

References 47 publications

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“…Production of amorpha-4,11-diene and artemisinic acid were further increased by galactose-regulated (P GAL1 ) expression of the UPC2-1 transcription factor (13). UPC2-1 encodes an activated allele of UPC2 (17,18), which increases transcription of most ergosterol pathway biosynthetic genes and is also a regulator of hypoxia-expressed genes. We decided to reconstruct the production strain so that every mevalonate pathway enzyme as far as ERG20 is transcribed from high-expression galactose-regulated promoters (P GAL1 or P GAL10 ).…”

Section: Resultsmentioning

confidence: 99%

Production of amorphadiene in yeast, and its conversion to dihydroartemisinic acid, precursor to the antimalarial agent artemisinin

Westfall

Pitera

Lenihan

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

624

448

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Malaria, caused by Plasmodium sp , results in almost one million deaths and over 200 million new infections annually. The World Health Organization has recommended that artemisinin-based combination therapies be used for treatment of malaria. Artemisinin is a sesquiterpene lactone isolated from the plant Artemisia annua . However, the supply and price of artemisinin fluctuate greatly, and an alternative production method would be valuable to increase availability. We describe progress toward the goal of developing a supply of semisynthetic artemisinin based on production of the artemisinin precursor amorpha-4,11-diene by fermentation from engineered Saccharomyces cerevisiae , and its chemical conversion to dihydroartemisinic acid, which can be subsequently converted to artemisinin. Previous efforts to produce artemisinin precursors used S. cerevisiae S288C overexpressing selected genes of the mevalonate pathway [Ro et al. (2006) Nature 440:940–943]. We have now overexpressed every enzyme of the mevalonate pathway to ERG20 in S. cerevisiae CEN.PK2, and compared production to CEN.PK2 engineered identically to the previously engineered S288C strain. Overexpressing every enzyme of the mevalonate pathway doubled artemisinic acid production, however, amorpha-4,11-diene production was 10-fold higher than artemisinic acid. We therefore focused on amorpha-4,11-diene production. Development of fermentation processes for the reengineered CEN.PK2 amorpha-4,11-diene strain led to production of > 40 g/L product. A chemical process was developed to convert amorpha-4,11-diene to dihydroartemisinic acid, which could subsequently be converted to artemisinin. The strains and procedures described represent a complete process for production of semisynthetic artemisinin.

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Section: Resultsmentioning

confidence: 99%

Production of amorphadiene in yeast, and its conversion to dihydroartemisinic acid, precursor to the antimalarial agent artemisinin

Westfall

Pitera

Lenihan

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

624

448

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“…In addition, in response to low oxygen levels, Sre1 stimulates transcription of genes required for adaptation to hypoxia. In budding yeast, several transcription factors (Upc2, Ecm22, Mga2, Hap1, Rox1, …) have been implicated in the response to sterol depletion and/or hypoxia, but none present significant sequence homology with members of the SREBP family (57,58,63,64). We have, therefore, investigated the effect of the deletion of TPA1 on genes controlled by Mga2 and Hap1 as representative of transcription factors affecting the response to oxygen concentration.…”

Section: Tpa1 Is Involved In Regulation Of Hap1 Transcription Factormentioning

confidence: 99%

Structural and Functional Insights into Saccharomyces cerevisiae Tpa1, a Putative Prolylhydroxylase Influencing Translation Termination and Transcription

Henri

Rispal

Bayart

et al. 2010

Journal of Biological Chemistry

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Efficiency of translation termination relies on the specific recognition of the three stop codons by the eukaryotic translation termination factor eRF1. To date only a few proteins are known to be involved in translation termination in eukaryotes. Saccharomyces cerevisiae Tpa1, a largely conserved but uncharacterized protein, has been described to associate with a messenger ribonucleoprotein complex located at the 3 end of mRNAs that contains at least eRF1, eRF3, and Pab1. Deletion of the TPA1 gene results in a decrease of translation termination efficacy and an increase in mRNAs half-lives and longer mRNA poly(A) tails. In parallel, Schizosaccharomyces pombe Ofd1, a Tpa1 ortholog, and its partner Nro1 have been implicated in the regulation of the stability of a transcription factor that regulates genes essential for the cell response to hypoxia. To gain insight into Tpa1/ Ofd1 function, we have solved the crystal structure of S. cerevisiae Tpa1 protein. This protein is composed of two equivalent domains with the double-stranded ␤-helix fold. The N-terminal domain displays a highly conserved active site with strong similarities with prolyl-4-hydroxylases. Further functional studies show that the integrity of Tpa1 active site as well as the presence of Yor051c/Ett1 (the S. cerevisiae Nro1 ortholog) are essential for correct translation termination. In parallel, we show that Tpa1 represses the expression of genes regulated by Hap1, a transcription factor involved in the response to levels of heme and oxygen. Altogether, our results support that Tpa1 is a putative enzyme acting as an oxygen sensor and influencing several distinct regulatory pathways.Protein synthesis is a complex process performed by ribosomes, translation factors, and amino-acyl tRNAs that act synergistically to translate mRNAs into corresponding proteins. The mechanism of translation of mRNAs into protein can be divided into three major steps; they are initiation, elongation, and termination. In eukaryotes, translation initiation relies on the formation of a stable closed-loop structure bringing the 5Ј m 7 G cap and the 3Ј poly(A) tail of a single mRNA in proximity and requires at least 11 initiation factors (1, 2). During elongation, the mRNA codon present in the ribosomal A site is recognized by a cognate amino-acyl tRNA associated with elongation factor 1A. The nascent polypeptide chain is then transferred from the tRNA present in the P-site to the amino acid of the A-site tRNA. Subsequently, elongation factor 2 induces translocation of peptidyl-tRNA from the A-to the P-site allowing the next elongation step to proceed. The entrance of one of the three stop codons (UAA, UAG, or UGA) in the A-site triggers translation termination. In contrast with other codons, stop codons are not recognized by cognate tRNAs but by proteins known as class I release factors (RF1 6 and RF2 in bacteria and eRF1 in eukaryotes). These are also directly involved in the hydrolysis of the ester bond connecting the newly synthesized polypeptide chain to the tRNA located...

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“…In S. cerevisiae it has been observed that the cell senses oxygen availability through cellular heme and sterol levels (27)(28)(29). In C. albicans, no apparent homolog of ScHAP1 exists, but in recent studies a close ortholog of S. cerevisiae Upc2p and Ecm22p, both involved in sensing sterol depletion, has been identified.…”

Section: Oxygen Sensing In Candida Albicansmentioning

confidence: 99%

Regulation of hypoxia adaptation: an overlooked virulence attribute of pathogenic fungi?

Grahl¹,

Cramer²

2009

Med. Mycology

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SummaryOver the past two decades, the incidence of fungal infections has dramatically increased. This is primarily due to increases in the population of immunocompromised individuals attributed to HIV/ AIDS pandemic and immunosuppression therapies associated with organ transplantation, cancer, and other diseases where new immunomodulatory therapies are utilized. Significant advances have been made in understanding how fungi cause disease, but clearly much remains to be learned about the pathophysiology of these often lethal infections.Fungal pathogens face numerous environmental challenges as they colonize and infect mammalian hosts. Regardless of a pathogen's complexity, its ability to adapt to environmental changes is critical for its survival and ability to cause disease. For example, at sites of fungal infections, the significant influx of immune effector cells and the necrosis of tissue by the invading pathogen generate hypoxic microenvironments to which both the pathogen and host cells must adapt in order to survive. However, our current knowledge of how pathogenic fungi adapt to and survive in hypoxic conditions during fungal pathogenesis is limited. Recent studies have begun to observe that the ability to adapt to various levels of hypoxia is an important component of the virulence arsenal of pathogenic fungi. In this review, we focus on known oxygen sensing mechanisms that non-pathogenic and pathogenic fungi utilize to adapt to hypoxic microenvironments and their possible relation to fungal virulence.

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A Role for Sterol Levels in Oxygen Sensing in Saccharomyces cerevisiae

Cited by 100 publications

References 47 publications

Production of amorphadiene in yeast, and its conversion to dihydroartemisinic acid, precursor to the antimalarial agent artemisinin

Production of amorphadiene in yeast, and its conversion to dihydroartemisinic acid, precursor to the antimalarial agent artemisinin

Structural and Functional Insights into Saccharomyces cerevisiae Tpa1, a Putative Prolylhydroxylase Influencing Translation Termination and Transcription

Regulation of hypoxia adaptation: an overlooked virulence attribute of pathogenic fungi?

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