Impact of Oxidative Stress on Ascorbate Biosynthesis in Chlamydomonas via Regulation of the VTC2 Gene Encoding a GDP-l-galactose Phosphorylase

Urzica, Eugen I.; Adler, Lital N.; Page, M. Dudley; Linster, Carole L.; Arbing, M.A.; Casero, David; Pellegrini, Matteo; Merchant, Sabeeha; Clarke, Steven

doi:10.1074/jbc.m112.341982

Cited by 97 publications

(115 citation statements)

References 66 publications

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“…Cytosolic chaperones deliver the copper they receive from plasma membrane transporters to two highly conserved copper-transporting P-type ATPases. Chlamydomonas, which synthesizes ascorbate, uses cytochrome b 561 to regenerate reduced ascorbate in the secretory pathway lumen (Urzica et al, 2012). Optimal PAM activity occurs under acidic conditions, which are created by the vacuolar ATPase (V-ATPase), which is also highly conserved in Chlamydomonas (Table S1).…”

Section: Discussionmentioning

confidence: 99%

Early eukaryotic origins for cilia-associated bioactive peptide-amidating activity

Kumar

Blaby‐Haas

Merchant

et al. 2016

Journal of Cell Science

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Ciliary axonemes and basal bodies were present in the last eukaryotic common ancestor and play crucial roles in sensing and responding to environmental cues. Peptidergic signaling, generally considered a metazoan innovation, is essential for organismal development and homeostasis. Peptidylglycine α-amidating monooxygenase (PAM) is crucial for the last step of bioactive peptide biosynthesis. However, identification of a complete PAM-like gene in green algal genomes suggests ancient evolutionary roots for bioactive peptide signaling. We demonstrate that the Chlamydomonas reinhardtii PAM gene encodes an active peptide-amidating enzyme (CrPAM) that shares key structural and functional features with the mammalian enzyme, indicating that components of the peptide biosynthetic pathway predate multicellularity. In addition to its secretory pathway localization, CrPAM localizes to cilia and tightly associates with the axonemal superstructure, revealing a new axonemal enzyme activity. This localization pattern is conserved in mammals, with PAM present in both motile and immotile sensory cilia. The conserved ciliary localization of PAM adds to the known signaling capabilities of the eukaryotic cilium and provides a potential mechanistic link between peptidergic signaling and endocrine abnormalities commonly observed in ciliopathies.

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Section: Discussionmentioning

confidence: 99%

Early eukaryotic origins for cilia-associated bioactive peptide-amidating activity

Kumar

Blaby‐Haas

Merchant

et al. 2016

Journal of Cell Science

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“…For example, recent sequencing technology has generated more large-scale measurement of gene expression and TF binding and produced ChIP-seq (for chromatin immunoprecipitation followed by massively parallel DNA sequencing) and RNA-seq (for high throughout sequencing of RNA) data sets in many species (Johnson et al, 2007;Robertson et al, 2007). There are already four RNAseq data sets available in the Gene Expression Omnibus (GEO) and 15 samples available in the Sequence Read Archive in C. reinhardtii Castruita et al, 2011;Fischer et al, 2012;Urzica et al, 2012). Although the number is still small and the dataprocessing strategies (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, another green algal species, Volvox carteri, that is close to C. reinhardtii in evolution has been recently sequenced, which provides a great opportunity to study the C. reinhardtii genome by comparative genomics (Prochnik et al, 2010). In addition to the genomic sequence data, there is a large supply of expression data available as complementary DNA libraries, ESTs, microarray expression measurements, and RNA sequencing reads (Eberhard et al, 2006;Miller et al, 2010;Castruita et al, 2011;Fischer et al, 2012;Urzica et al, 2012). Integrative analysis of DNA sequence data and mRNA expression measurements have been shown to be successful in gene regulatory network studies at the whole-genome level (Segal et al, 2003;Wang and Stormo, 2003).…”

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confidence: 99%

Systematic Prediction of cis-Regulatory Elements in the Chlamydomonas reinhardtii Genome Using Comparative Genomics

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2012

Plant Physiology

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Chlamydomonas reinhardtii is one of the most important microalgae model organisms and has been widely studied toward the understanding of chloroplast functions and various cellular processes. Further exploitation of C. reinhardtii as a model system to elucidate various molecular mechanisms and pathways requires systematic study of gene regulation. However, there is a general lack of genome-scale gene regulation study, such as global cis-regulatory element (CRE) identification, in C. reinhardtii. Recently, large-scale genomic data in microalgae species have become available, which enable the development of efficient computational methods to systematically identify CREs and characterize their roles in microalgae gene regulation. Here, we performed in silico CRE identification at the whole genome level in C. reinhardtii using a comparative genomics-based method. We predicted a large number of CREs in C. reinhardtii that are consistent with experimentally verified CREs. We also discovered that a large percentage of these CREs form combinations and have the potential to work together for coordinated gene regulation in C. reinhardtii. Multiple lines of evidence from literature, gene transcriptional profiles, and gene annotation resources support our prediction. The predicted CREs will serve, to our knowledge, as the first large-scale collection of CREs in C. reinhardtii to facilitate further experimental study of microalgae gene regulation. The accompanying software tool and the predictions in C. reinhardtii are also made available through a Web-accessible database (http://hulab.ucf.edu/research/projects/Microalgae/sdcre/motifcomb.html).

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“…mechanisms to osmotic stress, to oxidative stress, and to nutrient limitation have been widely studied and elucidated in freshwater and marine microalgae (Gee et al, 1993;Tanaka et al, 2011;Urzica et al, 2012;Schmollinger et al, 2014). Many of these responses involve substantial changes to primary metabolism.…”

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Two Glycerol-3-Phosphate Dehydrogenases from Chlamydomonas Have Distinct Roles in Lipid Metabolism

et al. 2017

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The metabolism of glycerol-3-phosphate (G3P) is important for environmental stress responses by eukaryotic microalgae. G3P is an essential precursor for glycerolipid synthesis and the accumulation of triacylglycerol (TAG) in response to nutrient starvation. G3P dehydrogenase (GPDH) mediates G3P synthesis, but the roles of specific GPDH isoforms are currently poorly understood. Of the five GPDH enzymes in the model alga Chlamydomonas reinhardtii, GPD2 and GPD3 were shown to be induced by nutrient starvation and/or salt stress. Heterologous expression of GPD2, a putative chloroplastic GPDH, and GPD3, a putative cytosolic GPDH, in a yeast gpd1D mutant demonstrated the functionality of both enzymes. C. reinhardtii knockdown mutants for GPD2 and GPD3 showed no difference in growth but displayed significant reduction in TAG concentration compared with the wild type in response to phosphorus or nitrogen starvation. Overexpression of GPD2 and GPD3 in C. reinhardtii gave distinct phenotypes. GPD2 overexpression lines showed only subtle metabolic phenotypes and no significant alteration in growth. In contrast, GPD3 overexpression lines displayed significantly inhibited growth and chlorophyll concentration, reduced glycerol concentration, and changes to lipid composition compared with the wild type, including increased abundance of phosphatidic acids but reduced abundance of diglycerides, triglycerides, and phosphatidylglycerol lipids. This may indicate a block in the downstream glycerolipid metabolism pathway in GPD3 overexpression lines. Thus, lipid engineering by GPDH modification may depend on the activities of other downstream enzyme steps. These results also suggest that GPD2 and GPD3 GPDH isoforms are important for nutrient starvation-induced TAG accumulation but have distinct metabolic functions.

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Impact of Oxidative Stress on Ascorbate Biosynthesis in Chlamydomonas via Regulation of the VTC2 Gene Encoding a GDP-l-galactose Phosphorylase

Cited by 97 publications

References 66 publications

Early eukaryotic origins for cilia-associated bioactive peptide-amidating activity

Early eukaryotic origins for cilia-associated bioactive peptide-amidating activity

Systematic Prediction of cis-Regulatory Elements in the Chlamydomonas reinhardtii Genome Using Comparative Genomics

Two Glycerol-3-Phosphate Dehydrogenases from Chlamydomonas Have Distinct Roles in Lipid Metabolism

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