Abstract
We successfully introduced targeted knock-out of gene of interest in Chlamydomonas reinhardtii by using DNA-free CRISPR. In this protocol, the detailed procedures of an entire workflow cover from the initial target selection of CRISPR to the mutant analysis using next generation sequencing (NGS) technology. Furthermore, we introduce a web-based set of tools, named CRISPR RGEN tools (http://www.rgenome.net/), which provides all required tools from CRISPR target design to NGS data analysis.
Keywords: Genome editing, CRISPR-Cas9, Microalgae, Ribonucleoproteins, Chlamydomonas reinhardtii, DNA-free transformation
Background
We recently reported (Baek et al., 2016) a one-step transformation of the model green microalga Chlamydomonas reinhardtii (Harris, 2001) using preassembled Cas9 protein-guide RNA ribonucleoproteins (RNPs). The manner of DNA-free CRISPR-Cas9 delivery has several advantages such as no need for codon optimization and specific promoters in different species of microalgae. Furthermore, it reduces off-target effects and may also be less cytotoxic in cells because the Cas9 protein is transiently active and then degraded by endogenous proteases in cells (Kim et al., 2014). In addition, the resulting gene-edited microalgae could be exempt from genetically modified organism (GMO) regulations due to the absence of foreign DNA sequences. In this protocol, the detailed procedures of an entire workflow are contained from the initial target selection of CRISPR to the mutant analysis using NGS technology (Bae et al., 2014a and 2014b; Park et al., 2015 and 2017).
Materials and Reagents
Equipment
Procedure
Data analysis
Recipes
Acknowledgments
This protocol was originally published as part of Baek et al. (2016). The authors especially thank Dr. Duk Hyoung Kim for developing the method. This work was supported by grants from the Korea CCS R&D Center (KCRC) (NRF-2014M1A8A1049273) to E.J. and the Plant Molecular Breeding Center of Next Generation BioGreen 21 Program (PJ01119201) to S.B.
References
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