Blue-light regulation of phytoene dehydrogenase ( carB ) gene expression in Mucor circinelloides

Velayos, Antonio; Blasco, José L.; Alvarez, M. I.; Iturriaga, Enrique A.; Eslava, Arturo P.

doi:10.1007/s004250050701

Cited by 87 publications

(68 citation statements)

References 43 publications

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“…The silencing of carB, a gene required for carotenoid biosynthesis, results in albino colonies that strongly contrast with the brightyellow phenotype of the wild-type strain in the light. Two different endogenous promoters were used to drive transcription of the carB transgene, the strong gpd1 promoter, which is active during vegetative growth and is regulated by the carbon source (37), and the light-induced carB promoter (36). Plasmid pMAT1253 expresses a carB hpRNA comprising an 840-bp stem and a 349-bp loop under the control of the gpd1 promoter and the Aspergillus nidulans trpC terminator (Fig.…”

Section: Resultsmentioning

confidence: 99%

A Single dicer Gene Is Required for Efficient Gene Silencing Associated with Two Classes of Small Antisense RNAs in Mucor circinelloides

et al. 2009

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RNA silencing in the zygomycete Mucor circinelloides exhibits uncommon features, such as induction by self-replicative sense transgenes and the accumulation of two size classes of antisense small interfering RNAs (siRNAs). To investigate whether this silencing phenomenon follows the rules of a canonical RNA-silencing mechanism, we used hairpin RNA (hpRNA)-producing constructs as silencing triggers and analyzed the efficiency and stability of silencing in different genetic backgrounds. We show here that the dsRNA-induced silencing mechanism is also associated with the accumulation of two sizes of antisense siRNAs and that this mechanism is not mediated by the previously known dcl-1 (dicer-like) gene, which implies the existence of an additional dicer gene. An M. circinelloides dcl-2 gene was cloned and characterized, and the corresponding null mutant was generated by gene replacement. This mutant is severely impaired in the silencing mechanism induced by self-replicative sense or inverted-repeat transgenes, providing the first genetic evidence of a canonical silencing mechanism in this class of fungus and pointing to a role for dcl-2 in the mechanism. Moreover, a functional dcl-2 gene is required for the normal accumulation of the two sizes of antisense RNAs, as deduced from the analysis of dcl-2 ؊ transformants containing hpRNA-expressing plasmids. In addition to its critical role in transgene-induced silencing, the dcl-2 gene seems to play a role in the control of vegetative development, since the dcl-2 null mutants showed a significant decrease in their production of asexual spores.RNA-mediated gene silencing (RNA silencing) acts through transcriptional and posttranscriptional mechanisms to suppress gene expression in a sequence-specific manner. Widespread among plants, animals, and fungi, these mechanisms are involved in a wide variety of biological processes, including defense against viruses and transposons, the regulation of endogenous gene expression, and heterochromatin formation (reviewed in references 2, 5, 31, and 35). Although a number of specialized RNA-silencing pathways have been reported, a common mechanism has emerged, with homologous genes and proteins acting in different organisms. A central feature in all of these silencing phenomena is the processing of doublestranded RNA (dsRNA) (long dsRNA and pre-microRNAs [miRNAs]) into small duplexes of 21 to 25 nucleotides (nt) (small interfering RNAs [siRNAs] and miRNAs) by the RNase III enzyme Dicer. The small RNAs generated by Dicer are subsequently incorporated into the RNA-induced silencing complex (RISC), where they are used as a guide for the sequence-specific degradation of the target mRNA, the repression of its translation, or the inhibition of its transcription.The Dicer endonucleases are multidomain proteins evolutionarily conserved in eukaryotes. In metazoans and plants, in addition to two copies of the RNase III domain and a dsRNAbinding domain at the carboxyl terminus, the Dicer proteins include an amino-terminal ATP-dependent RNA helicas...

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Section: Resultsmentioning

confidence: 99%

A Single dicer Gene Is Required for Efficient Gene Silencing Associated with Two Classes of Small Antisense RNAs in Mucor circinelloides

et al. 2009

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“…Four introns of 69, 57, 56 and 59 bp are present in malEMc from Mc. circinelloides, and for this species the mean size of an intron is 69 bp (Velayos et al, 2000). The sequence of malEMt has a G+C content of 54 %, whereas the introns have a G+C content of 49 %.…”

Section: Characterization Of the Transformed Strainsmentioning

confidence: 96%

Malic enzyme: the controlling activity for lipid production? Overexpression of malic enzyme in Mucor circinelloides leads to a 2.5-fold increase in lipid accumulation

2007

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“…2), and experiments should be done on additional Mucorales members to figure out the mechanism of action. The induction effect of synthetic analogues (12,13) in B. trispora is curious, and further studies on the biological functions of these metabolites are essential to make valid conclusions. The inefficiency of stimulants on ␤-carotene production in plus strains of both Blakeslea and M. mucedo (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Phytoene synthase and lycopene cyclase (CarRA), along with phytoene dehydrogenase (CarB), convert the first colorless linear C 40 carotenoid, phytoene ( Fig. 1), to yellow-pigmented ␤-carotene (12,13). Little is known about the physiological functions of enzymes or the products of ␤-carotene cleavage and trisporic acid biogenesis within the Mucorales.…”

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confidence: 99%

Early and Late Trisporoids Differentially Regulate β-Carotene Production and Gene Transcript Levels in the Mucoralean Fungi Blakeslea trispora and Mucor mucedo

Sahadevan

Richter-Fecken

Kaerger

et al. 2013

Appl Environ Microbiol

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Blakeslea trispora displayed a very high transcript turnover in the gene for carotenoid cleavage dioxygenase, tsp3, during the sexual phase. An in vivo enzyme assay and chromatographic analysis led to the identification of ␤-apo-12=-carotenal as the first apocarotenoid involved in trisporic acid biosynthesis in B. trispora. Supplementation of C 18 trisporoids, namely D'orenone, methyl trisporate C, and trisporin C, increased tsp3 transcripts in the plus compared to minus partners. Interestingly, the tsp1 gene, which is involved in trisporic acid biosynthesis, was downregulated compared to tsp3 irrespective of asexual or sexual phase. Only the minus partners of both B. trispora and Mucor mucedo had enhanced ␤-carotene production after treatment with C 20 apocarotenoids, 15 different trisporoids, and their analogues. We conclude that the apocarotenoids and trisporoids influence gene transcription and metabolite production, depending upon the fungal strain, corresponding genus, and developmental phase, representing a "chemical dialect" during sexual communication. Mucorales fungi belonging to the subphylum incertae sedis Mucoromycotina (formerly classified in the class Zygomycetes) comprise 9 families, 51 genera, and around 205 species (1). These basal fungi are fast-growing soil saprotrophs that feed on dead and decaying organic matter. The asexual phase predominates their life cycle, with multinucleated haploid sporangiospores that germinate to mycelia of either the plus or minus mating type in heterothallic strains. Adversities, like environmental stresses or nutrient depletion, especially of nitrogen and phosphorus (2), lead to the sexual phase, in which complementary mating partners in close proximity exchange metabolites and form special aerial hyphae known as zygophores. The fusion of zygophores results in thousands of nuclei from both parents in the morphologically modified structure known as the progametangia. During further structural modifications and dormancy, which may extend from months to a year, most of the nuclei undergo degradation. Finally, gametangia bearing two nuclei from opposite partners fuse to form a thick-walled dikaryotic sexual spore known as the zygospore. Mitosis followed by meiosis results in four haploid products in a sporangium that develops from the zygospore (3). One Mucorales species in particular, Blakeslea trispora, has been commercially exploited for its potential to produce an excess of carotenoids, like ␤-carotene and lycopene, during its sexual phase of the life cycle (4, 5). According to a new report by Global Industrial Analysts, Inc., the worldwide market for carotenoids is projected to reach $1.3 billion by 2017. Hence, microbial carotenoids have been in the limelight as an ecofriendly sustainable alternative source for synthetics. Mucoralean carotenoids are not only under investigation for their biotechnological applications but also to help in understanding how they influence the sexual phase in those fungi.Apocarotenoids are the unsaturated nonpolar isoprenoids form...

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Blue-light regulation of phytoene dehydrogenase ( carB ) gene expression in Mucor circinelloides

Cited by 87 publications

References 43 publications

A Single dicer Gene Is Required for Efficient Gene Silencing Associated with Two Classes of Small Antisense RNAs in Mucor circinelloides

A Single dicer Gene Is Required for Efficient Gene Silencing Associated with Two Classes of Small Antisense RNAs in Mucor circinelloides

Malic enzyme: the controlling activity for lipid production? Overexpression of malic enzyme in Mucor circinelloides leads to a 2.5-fold increase in lipid accumulation

Early and Late Trisporoids Differentially Regulate β-Carotene Production and Gene Transcript Levels in the Mucoralean Fungi Blakeslea trispora and Mucor mucedo

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