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Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land(More)
Nitrogen (N) is a key nutrient that limits global primary productivity; hence, N-use efficiency is of compelling interest in agriculture and aquaculture. We used Chlamydomonas reinhardtii as a reference organism for a multicomponent analysis of the N starvation response. In the presence of acetate, respiratory metabolism is prioritized over photosynthesis;(More)
The Chlamydomonas reinhardtii transcription factor PSR1 is required for the control of activities involved in scavenging phosphate from the environment during periods of phosphorus limitation. Increased scavenging activity reflects the development of high-affinity phosphate transport and the expression of extracellular phosphatases that can cleave phosphate(More)
The molecular mechanisms underlying the onset of Fe-deficiency chlorosis and the maintenance of photosynthetic function in chlorotic chloroplasts are relevant to global photosynthetic productivity. We describe a series of graded responses of the photosynthetic apparatus to Fe-deficiency, including a novel response that occurs prior to the onset of(More)
Photosynthetic organisms are among the earliest life forms on earth and their biochemistry is strictly dependent on a wide range of inorganic nutrients owing to the use of metal cofactor-dependent enzymes in photosynthesis, respiration, inorganic nitrogen and sulfur assimilation. Chlamydomonas reinhardtii is a photosynthetic eukaryotic model organism for(More)
Crd1 (Copper response defect 1), which is required for the maintenance of photosystem I and its associated light-harvesting complexes in copper-deficient (-Cu) and oxygen-deficient (-O(2)) Chlamydomonas reinhardtii cells, is localized to the thylakoid membrane. A related protein, Cth1 (Copper target homolog 1), is shown to have a similar but not identical(More)
A genetic screen for Chlamydomonas reinhardtii mutants with copper-dependent growth or nonphotosynthetic phenotypes revealed three loci, COPPER RESPONSE REGULATOR 1 (CRR1), COPPER RESPONSE DEFECT 1 (CRD1), and COPPER RESPONSE DEFECT 2 (CRD2), distinguished as regulatory or target genes on the basis of phenotype. CRR1 was shown previously to be required for(More)
Organisms exhibit a diverse set of responses when exposed to low-phosphate conditions. Some of these responses are specific for phosphorus limitation, including responses that enable cells to efficiently scavenge phosphate from internal and external stores via the production of high-affinity phosphate transporters and the synthesis of intracellular and(More)
The Chlamydomonas reinhardtii PSR1 gene is required for proper acclimation of the cells to phosphorus (P) deficiency. P-starved psr1 mutants show signs of secondary sulfur (S) starvation, exemplified by the synthesis of extracellular arylsulfatase and the accumulation of transcripts encoding proteins involved in S scavenging and assimilation. Epistasis(More)
The unicellular green alga Chlamydomonas reinhardtii is a valuable model for studying metal metabolism in a photosynthetic background. A search of the Chlamydomonas expressed sequence tag database led to the identification of several components that form a copper-dependent iron assimilation pathway related to the high-affinity iron uptake pathway defined(More)