Isolation and characterization of a stress-responsive gene encoding a CHRD domain-containing protein from a halotolerant green alga

Gene. 2018 Jan 15:640:14-20. doi: 10.1016/j.gene.2017.10.012. Epub 2017 Oct 7.


The genetic basis of stress resistance in extremophilic microalgae is not well studied. In this study, a gene of unknown function, the cluster58 or CL58 gene, was identified from the halotolerant green alga Chlamydomonas W80 and characterized. The CL58 gene encodes a protein containing a domain of unknown function, the CHRD domain, and a putative secretory signaling sequence at its N-terminus. The levels of CL58 mRNA increased in response to high copper levels and low temperatures. When the CL58 gene was heterologously expressed as a fusion gene with the NanoLuc luciferase gene in Chlamydomonas reinhardtii, a majority of the NanoLuc activity was detected in the culture medium compared with that in the intracellular fraction. A mutagenic analysis revealed that the putative secretory signaling sequence was sufficient for the secretion of the CL58-NanoLuc fusion protein. In addition, we expressed the protein encoded by the CL58 gene in Escherichia coli; the recombinant, soluble protein was then purified. In summary, we identified a novel gene from C. W80 that appears to encode a stress-responsive, CHRD domain-containing secreted protein.

Keywords: Chlamydomonas reinhardtii; Recombinant protein; Secretory protein; Stress response; Unknown function.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Chlamydomonas reinhardtii / genetics*
  • Chlamydomonas reinhardtii / growth & development
  • Chlamydomonas reinhardtii / metabolism
  • Cold Temperature
  • Copper / toxicity
  • DNA, Algal / genetics*
  • Glycoproteins / chemistry*
  • Intercellular Signaling Peptides and Proteins / chemistry*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Protein Domains
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Homology
  • Stress, Physiological / genetics*
  • Transgenes / genetics*


  • DNA, Algal
  • Glycoproteins
  • Intercellular Signaling Peptides and Proteins
  • Plant Proteins
  • Recombinant Proteins
  • Copper
  • chordin