moxMaple3: a Photoswitchable Fluorescent Protein for PALM and Protein Highlighting in Oxidizing Cellular Environments

Sci Rep. 2018 Oct 3;8(1):14738. doi: 10.1038/s41598-018-32955-5.


The ability of fluorescent proteins (FPs) to fold robustly is fundamental to the autocatalytic formation of the chromophore. While the importance of the tertiary protein structure is well appreciated, the impact of individual amino acid mutations for FPs is often not intuitive and requires direct testing. In this study, we describe the engineering of a monomeric photoswitchable FP, moxMaple3, for use in oxidizing cellular environments, especially the eukaryotic secretory pathway. Surprisingly, a point mutation to replace a cysteine substantially improved the yield of correctly folded FP capable of chromophore formation, regardless of cellular environment. The improved folding of moxMaple3 increases the fraction of visibly tagged fusion proteins, as well as FP performance in PALM super-resolution microscopy, and thus makes moxMaple3 a robust monomeric FP choice for PALM and optical highlighting applications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / chemistry
  • Cysteine / chemistry*
  • Eukaryotic Cells / metabolism*
  • Green Fluorescent Proteins / chemistry*
  • Green Fluorescent Proteins / genetics
  • Humans
  • Luminescent Proteins / chemistry*
  • Luminescent Proteins / genetics
  • Microscopy, Fluorescence / methods
  • Oxidation-Reduction
  • Protein Folding
  • Protein Structure, Tertiary / genetics


  • Amino Acids
  • Luminescent Proteins
  • Green Fluorescent Proteins
  • Cysteine