A codon-optimized luciferase from Gaussia princeps facilitates the in vivo monitoring of gene expression in the model alga Chlamydomonas reinhardtii

Curr Genet (2008) 53:381388

DOI 10.1007/s00294-008-0189-7

TECHNICAL NOTE

A codon-optimized luciferase from Gaussia princeps facilitates the in vivo monitoring of gene expression in the model alga Chlamydomonas reinhardtii

Ning Shao Ralph Bock

Received: 10 January 2008 / Revised: 20 March 2008 / Accepted: 29 March 2008 / Published online: 12 April 2008 The Author(s) 2008

Abstract The unicellular green alga Chlamydomonas reinhardtii has emerged as a superb model species in plant biology. Although the alga is easily transformable, the low eYciency of transgene expression from the Chlamydomonas nuclear genome has severely hampered functional genomics research. For example, poor transgene expression is held responsible for the lack of sensitive reporter genes to monitor gene expression in vivo, analyze subcellular protein localization or study proteinprotein interactions. Here, we have tested the luciferase from the marine copepod Gaussia princeps (G-Luc) for its suitability as a sensitive bioluminescent reporter of gene expression in Chlamydomonas. We show that a Gaussia luciferase gene variant, engineered to match the codon usage in the Chlamydomonas nuclear genome, serves as a highly sensitive reporter of gene expression from both constitutive and inducible algal promoters. Its bioluminescence signal intensity greatly surpasses previously developed reporters for Chlamydomonas nuclear gene expression and reaches values high enough for utilizing the reporter as a tool to monitor responses to environmental stresses in vivo and to conduct high-throughput screenings for signaling mutants in Chlamydomonas.

Keywords Reporter gene Chlamydomonas reinhardtii

Luciferase Gaussia princeps Heat-inducible expression Bioluminescence

Introduction

The unicellular green alga Chlamydomonas reinhardtii has become an invaluable model organism for plant biology (Harris 2001; Gutman and Niyogi 2004; Prschold et al. 2005). It represents one of the simplest photosynthetic eukaryotes, can be easily grown at large scale either photo-autotrophically, mixotrophically or heterotrophically, and can be propagated sexually or asexually. Moreover, Chlamydomonas combines a powerful genetics with the availability of unique genetic and genomic resources: all three genomes are fully sequenced (nuclear, plastid, and mitochondrial; Merchant et al. 2007), large mutant collections have been established, and all three genomes are amenable to genetic manipulation by transformation (Hippler et al. 1998; Remacle et al. 2006). One of the few drawbacks of Chlamydomonas is that it has been notoriously diYcult to express transgenes to reasonably high levels from the nuclear genome. Use of specialized...