The shortest wavelength fluorescence reported to date makes dynamic cell imaging easier

OSAKA, Japan — Imagine how difficult it is to
visually track five people scattered across a stadium.
By tracking many different cytokines simultaneously, the researchers achieved even more astonishing achievements, but they needed an extended fluorescence toolkit to improve their current capabilities
.

Researchers recently published in the Institute of Science and Industry at Osaka University in Communication Biology in Japan genetically engineered a protein to have the shortest wavelength of fluorescence emission currently available
.

Fluorescence is a common means
of observing the internal activity of cells under a microscope.
For example, a biomolecule of interest can have a fluorescent protein (i.
e.
, fluorophore) attached to a gene that emits light
of a specific color (i.
e.
, wavelength).
By adding different fluorophores to different types of biomolecules (each emitting a different wavelength of light), one can identify and track all these different biomolecules
at the same time.
Expanding the range of wavelengths that may be emitted can increase the number of
biomolecules being tracked at the same time.
That's the problem
the researchers are trying to solve.

"The short emission wavelength limit of fluorescent proteins has remained unchanged for the past 10 years," explains
first author Kazunori Sugiura.
"This is because previous researchers have typically focused on making small changes
to one amino acid of the green fluorescent protein mutant.
"

Researchers at Osaka University instead focused on optimizing the interaction
between the fluorescence center, the chromophore, and the surrounding water molecules and amino acids.
By blocking the hydration of ionization and stabilizing chromophore, the synthesized fluorophore, called sumire, exhibits several notable fluorescence properties: (1) emission at 414 nanometers, a new record; (2) nearly four times brighter than state-of-the-art; and (3) stable emission in the pH range of 5.
5-9.
0, which covers most of the pH range
seen in most cells.

Senior author Takeharu Nagai said: "We also achieved fluorescence resonance energy transfer between Sumire and common commercial protein fluorophores, a common biomolecular imaging technique
.
" "This further illustrates Sumire's compatibility
with modern multiparameter analysis.
"

This work successfully expanded cell imaging tools with genetic engineering to modify the chromophore
of fluorescent proteins in a way that has not yet been taken into account.
The Osaka University researchers' approach will help further expand the range of fluorescence wavelengths available to engineered proteins, which will help researchers discover biological principles
that are important in normal health and disease.