The present invention provides a novel modified protein for detecting a chromatin open structure more sensitively and easily than the prior art as a new detection tool related to gene expression. The present invention relates to a nucleic acid-binding protein comprising a DNA-binding domain in which 3 or more TAL-repeats are repeatedly linked, wherein the nucleic acid-binding protein binds in a base sequence-independent manner, and a method for fluorescently labeling open chromatin in living cells, comprising a step of introducing a gene encoding a nucleic acid-binding protein into a living cell, wherein the nucleic acid-binding protein is a protein in which a DNA-binding domain in which 3 or more TAL-repeats are repeatedly linked and a fluorescent protein are directly or indirectly bound, and the DNA-binding domain binds to a nucleic acid in a base sequence-independent manner.
NUCLEIC ACID BINDING PROTEIN