1211-B 6 DECEMBER 2019 • VOL 366 ISSUE 6470 sciencemag.org SCIENCE
RESEARCH
HIV VACCINES
Engineering better bnAbs
A highly effective HIV vaccine
has been the goal of vaccin-
ologists for nearly 35 years. A
successful vaccine would need
to induce broadly neutralizing
antibodies (bnAbs) that are
capable of neutralizing multiple
HIV strains (see the Perspective
by Agazio and Torres). Steichen
et al. report a strategy in which
the first vaccine shot can lead to
immune responses that gener-
ate desired bnAbs. By combining
knowledge of human antibody
repertoires and structure to
guide design, they validated
candidate immunogens through
functional preclinical testing.
Saunders et al. designed
immunogens with differences
in binding strength for bnAb
precursors, which enabled
selection of rare mutations after
immunization. The immunogens
promoted bnAb precursor matu-
ration in humanized mice and
macaques. —PNK
Science, this issue p. 1216, p. 1215;
see also p. 1197
ASTEROIDS
Bennu ejects material
from its surface
Most asteroids appear inert, but
remote observations show that a
small number experience mass
loss from their surfaces. Lauretta
and Hergenrother et al. describe
close-range observations of
mass loss on the near-Earth
asteroid Bennu (see the
Perspective by Agarwal). Shortly
after arriving at Bennu, naviga-
tion cameras on the OSIRIS-REx
(Origins, Spectral Interpretation,
Resource Identification, and
Security—Regolith Explorer)
spacecraft detected objects 1 to
10 centimeters in diameter mov-
ing above the surface. Analysis of
the objects’ trajectories showed
that they originated in discrete
ejection events from otherwise
unremarkable locations on
Bennu. Some objects remained
in orbit for several days, whereas
others escaped into interplane-
tary space. The authors suggest
multiple plausible mechanisms
that could underlie this activ-
ity. —KTS
Science, this issue p.1217;
see also p. 1192VOLCANOLOGY
Caldera collapse and
flank eruption
Real-time monitoring of volcanic
eruptions involving caldera-
forming events are rare
(see the Perspective by
Sigmundsson). Anderson et al.
used several types of geophysi-
cal observations to track the
caldera-forming collapse at
the top of Kīlauea Volcano,
Hawai‘i, during the 2018
eruption. Gansecki et al. used
near–real-time lava composi-
tion analysis to determine when
magma shifted from highly
viscous, slow-moving lava to
low-viscosity, fast-moving lava.
Patrick et al. used a range of
geophysical tools to connect
processes at the summit to lava
rates coming out of far-away fis-
sures. Together, the three studies
improve caldera-collapse models
and may help improve real-time
hazard responses. —BG
Science, this issue p. 1225, p. 1212,
p. 1213;
see also p. 1200SOLID-STATE PHYSICS
A timely look into
electron-phonon coupling
The coupling between electrons
and phonons—lattice vibrations
in solids—is responsible for
macroscopic quantum phenom-
ena such as superconductivity.
Yet, experimentally measuring
this coupling as a function of
momentum and for a particular
phonon mode is tricky. Na et al.
used time- and angle-resolved
photoemission spectroscopy to
excite electrons in graphite and
monitor their decay, which wasaccompanied by the release of
phonons. The time constants of
these decay processes provided
direct information on electron-
phonon couplings in this system.
—JS
Science, this issue p. 1231QUANTUM INFORMATION
Divacancies in a diodeSolid-state defects hold great
promise as the building blocks
for quantum computers. Most
research has focused on defects
in diamond, which are dif-
ficult to integrate with existing
semiconductor technologies.
An alternative two-vacancy
neutral defect in silicon carbide
(SiC) has a long coherence time
but suffers from broad optical
linewidths and charge instability.
Anderson et al. fabricated these
defects in a diode made out
of commercially available SiC.
Reverse voltage created large
electric fields within the diode,
tuning the frequencies of the
defect’s transitions by hundreds
of gigahertz. The electric fields
also caused charge depletion,
leading to a dramatic narrowing
of the transitions. The technique
should be readily generalizable
to other quantum defects. —JS
Science, this issue p. 1225STRUCTURAL BIOLOGY
Regulating synaptic
signals
In the brain, AMPA-type gluta-
mate receptors (AMPARs) are
ion channels that play key roles
in synaptic plasticity, cogni-
tion, learning, and memory. Two
classes of subunits, the claudin
family and the cornichon family,
regulate AMPAR gating and
trafficking. Previous structures
have been presented of AMPAR
bound to claudin homologs.
Now, Nakagawa reports a
high-resolution structure of
AMPAR bound to the cornichon
homolog CNIH3, determined by
cryo–electron microscopy (seethe Perspective by Schwenk and
Fakler). In contrast to a predicted
topology of three transmem-
brane helices and an intracellular
amino terminus, CNIH3 has four
transmembrane helices, and
both the amino and carboxyl
termini are extracellular. The
structure reveals the architec-
ture of the interaction interface
between AMPAR and CNIH3
and suggests a role for lipids
in regulating the assembly and
function of the AMPAR-CNIH3
complex. —VV
Science, this issue p. 1259;
see also p. 1194PHYSIOLOGY
Translating into a bigger
pancreas
The messenger RNA transla-
tion factor eIF5A promotes cell
proliferation during develop-
ment and in tumors. This ability
depends on eIF5A hypusination,
a posttranslational modification
specific to eIF5A. Levasseur et
al. found that eIF5A hypusination
was critical for postnatal expan-
sion of pancreatic b cell mass.
Mice that could not perform
hypusination in b cells did not
produce sufficient cyclin D2 to
sustain cell cycling and devel-
oped diabetes in response to
diet-induced obesity. Thus, eIF5A
hypusination enables b cells to
proliferate, which is required to
increase insulin production and
maintain glucose homeostasis.
—WW
Sci. Signal. 12 , eaax0715 (2019).IMMUNODEFICIENCIES
Putting JNK1 on the
immunodeficiency map
Impaired T helper 17 cell
immunity is the shared element
among a group of inherited
immunodeficiencies that are
associated with chronic mucocu-
taneous candidiasis (CMC). Li et
al. studied three patients from
a single family who had a com-
bination of CMC and an atypicalEdited by Stella HurtleyALSO IN SCIENCE JOURNALS
Published by AAAS