Reduction of PII signaling protein enhances lipid body production in Chlamydomonas reinhardtii.

Abstract

In all examined organisms that have the PII signal transduction machinery, PII coordinates the central C/N anabolic metabolism. In green algae and land plants, PII is localized in the chloroplast and controls the L-arginine biosynthetic pathway pathway. To elucidate additional functions of PII in the model photosynthetic organism Chlamydomonas reinhardtii (CrPII), we generated and analyzed four strains, in which PII was strongly under-expressed by artificial microRNA (GLB1-amiRNA strains). In response to nitrogen deficiency, Chlamydomonas produces triacylglycerols (TAGs) that are accumulated in lipid bodies (LB). Quantification of LBs by confocal microscopy in four GLB1-amiRNA strains showed that reduced PII levels resulted in over-accumulation of LBs compared to their parental strains. Moreover, knock-down of PII caused also an increase in the total TAG level. We propose that the larger yields of TAG-filled LBs in N-starved GLB1-amiRNA cells can be attributed to the strain's depleted PII level and their inability to properly control acetyl-CoA carboxylase activity (ACCase). Together, our results imply that PII in Chlamydomonas negatively controls TAG accumulation in LBs during acclimation to nitrogen starvation of the alga.

• Authors: Zhanneta Zalutskaya, Nina Kharatyan, Karl Forchhammer, Elena Ermilova
• Journal: Plant science : an international journal of experimental plant biology (Plant Sci) Vol. 240 Pg. 1-9 (Nov 2015) ISSN: 1873-2259 [Electronic] Ireland
• PMID: 26475183 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Chemical References

• Algal Proteins
• PII Nitrogen Regulatory Proteins
• Triglycerides
• Nitrogen

Topics

• Algal Proteins (genetics, metabolism)
• Chlamydomonas reinhardtii (genetics, metabolism)
• Gene Expression Regulation
• Gene Knockdown Techniques
• Lipid Droplets (metabolism)
• Nitrogen (deficiency)
• PII Nitrogen Regulatory Proteins (genetics, metabolism)
• Triglycerides (biosynthesis)