IMAGE: ELLA MARU STUDIOS, INC.364 22 APRIL 2022 • VOL 376 ISSUE 6591 science.org SCIENCE
may help in the development of
better optical devices. —BG
Science, abn7711, this issue p. 371PROTEIN DESIGN
Steps toward
a nanomachine
Protein rotary machines such as
ATP synthase contain axle-like
and ring-like components and
couple biochemical energy to
the mechanical work of rotating
the components relative to
each other. Courbet et al. have
taken a step toward designing
such axle-rotor nanomachines.
A structural requirement is that
interactions between the com-
ponents must be strong enough
to allow assembly but still allow
different rotational states to
be populated. The authors
met this design challenge and
computationally designed ring-
like protein topologies (rotors)
with a range of inner diameters
that accommodate designed
axle-like binding partners. The
systems assemble and populate
the different rotational states
anticipated by the designs.
These rotational energy
landscapes provide one of two
needed elements for a direc-
tional motor. —VV
Science, abm1183, this issue p. 383ORGANIC CHEMISTRY
Better C–C coupling
through ligand swaps
The development of cross-cou-
pling catalysis for carbon–carbon
bond formation revolutionized
pharmaceutical synthesis.
Nonetheless, one drawback of
the original reactions is the need
to activate one of the coupling
partners ahead of time. Recently,
chemists have focused on direct
coupling of two halocarbons,
which is efficient but poses a
selectivity challenge. Hamby et
al. report a nickel catalyst for
alkyl-aryl coupling that relies on
ligand exchanges in concert with
electrochemistry to react with
each partner consecutively and
thereby avoid alkyl-alkyl, aryl-aryl,
or isomerized by-products. —JSY
Science, abo0039, this issue p. 410ELECTROOPTICS
Breaking down
the domain walls
Ferroelectric materials should
make for decent optical com-
ponents because of the change
in refractive index with electric
field. However, many of the best
ferroelectrics have domain walls
that scatter light and are not
useful for optics applications.
Liu et al. used a high-tempera-
ture poling method to removethe light-scattering domain
walls in a lead ceramic ferro-
electric. The material has a very
high electro-optic coefficient
and requires a very low driving
voltage. This strategy may be
useful for other materials andEdited by Michael Funk
IN SCIENCE JOURNALSRESEARCH
CELL BIOLOGYCell division facilitates cell invasion
C
ell migration through compact tissues within multicellular organisms is essential for normal
embryonic development, immune response, and cancer metastasis. Frequently, migrating
cells find a path of least resistance; however, relatively little is known about invasion into cell-
dense tissues with no preexisting paths. Studying fruit flies, Akhmanova et al. discovered that
embryonic macrophages can penetrate into tissues when at least one surrounding tissue cell
divides at the site of invasion. Live imaging and genetic and optogenetic manipulations revealed
that macrophage invasion requires the release of intercellular adhesions, which occurs during divi-
sion. —BAP Science, abj0425, this issue p. 394Artist’s depiction of a macrophage penetrating
a tissue layer at a site of cell division