EDITED BY STELLA HURTLEY

Fathoming Publication
Fifty years ago the Nobel
Prize in chemistry was award-
Strategies
ed to Max Perutz and John While many studies have tracked numbers of cita-
Kendrew for determining the tions after publication, such studies cannot reveal
structure of globular proteins. how prepublication dynamics affects subsequent
Since first viewing their struc- citation history. Calcagno et al. (p. 1065, pub-
ture of myoglobin, scientists lished online 11 October) surveyed the submission
have sought to understand history of more than 80,000 articles published in
protein folding. Dill and 16 fields of biology in 2006–2008 and construct-
MacCallum (p. 1042) review ed a social network based on manuscript flows
the progress that has been among scientific journals. High-impact journals
made on three central ques- occupied central positions in the network. A
tions: What is the code that majority of manuscripts were published in the first
relates sequence to structure? journal to which they were submitted. However,
How do proteins fold so fast? submission history affected the post-publication
Can protein structure be com- impact (citation count) of articles, with manu-
putationally predicted? While
we have come some way to-
Protein Folding: scripts requiring resubmission eventually receiving
more citations.
ward answering these ques- Past and Future
tions, new questions have
been generated. It is no lon-
Exploiting Seismic Noise
ger useful to talk about “solving the protein-folding problem”—protein folding has grown into a Typically, seismic imaging has been
field of research where the next 50 years promise to be as exciting as the last. based on examining the seismic waves
that traveled from a known source,
usually an earthquake, to a seismo-
Forming the Moon subsequent fermentation. Ding et al. (p. 1055) graph. Poli et al. (p. 1063; see the
applied several different types of microscopy to Perspective by Prieto) now show that
from Earth understand the details of how cellulase enzymes correlations of body waves in seismic
It is thought that the Moon formed after a Mars- perform this task, in the interest of ultimately noise can yield information about
sized planet hit Earth about 4.5 billion years optimizing the procedure. After lignin removal, Earth’s deep interior. An array in Fin-
ago. Computer simulations of this event predict fungal cellulases penetrated the remaining land, supplemented by other stations,
that the Moon was produced primarily from ma- cellulose pore structure more efficiently than was used to examine reflections from
terial from the impacting planet. However, the did bacteria-derived multienzyme complexes. two major seismic boundaries within
Moon has a similar composition to that of Earth, However, this behavior hinges on a lignin extrac- Earth’s mantle at depths of about 410
and the impacting planet would likely have had tion scheme that preserves the native architecture and 660 km thought to be associated
a different composition. Prior models assumed of the cellulose. with mineralogical changes in Earth’s
that the impact left the Earth-Moon system with interior. The data imply that the upper
the same angular momentum as it has today discontinuity extends over about 15
(see the Perspective by Halliday). Ćuk and
When Molecules Collide kilometers whereas the deeper one is
Stewart (p. 1047, published online 17 October; As advances in computing power and algorithm only about 4 km thick.
see the cover) show that the angular momentum design parallel the increasing sophistication of
of the Earth-Moon system could have decreased experimental apparatus, theory and measure-
by half after the Moon-forming impact, opening ment are perpetually trading places as to which
Axing Autophagy
the door to new impact models. For example, can detail the dynamics of molecular interac- When intracellular pathogens like Legionella
simulations suggest that high-velocity impacts tions more precisely. At present, collisions of an pneumophila take up residence in mammalian
onto a fast-spinning early Earth can lead to a atom with a diatomic molecule can be studied host cells, they must combat the efforts of the
Moon formed primarily from Earth’s mantle. comparably in both domains. In contrast, host cell to attack them. Autophagy is a process
CREDITS (TOP TO BOTTOM): DILL ET AL.; POLI ET AL.

Canup (p. 1052, published online 17 October) collisions of two diatomics each bearing an by which cells digest their own constituents, often
considered instead lower-velocity impacts by unpaired electron manifest too many degrees of involved in response to starvation or pathogen
planets comparable in mass to the proto-Earth, freedom for computational quantum mechanics. attack. Choy et al. (p. 1072, published online
which could generate a Moon and an Earth with Kirste et al. (p. 1060) have now experimentally 25 October) now describe how L. pneumophila
similar compositions. resolved the rotational dynamics of one such can inhibit the autophagy pathway in eukaryotic
case—the inelastic scattering of NO + OH— cells, and provide a detailed description of the
and find that a simplified theoretical model biochemical mechanism. A Legionella effec-
Watching a Breakdown focusing on long range interactions predicts the tor protein, RavZ, acts as a very potent enzyme
One of the key challenges in scaling up biofuels outcome surprisingly well. Such approximations that specifically deconjugates a key autophagy
manufacturing is development of a cost-effective could render many analogous systems moder- protein, Atg8, from autophagosomal membranes,
way to break down cellulose into sugars for ately predictable. thus blocking autophagy.

1006 23 NOVEMBER 2012 VOL 338 SCIENCE www.sciencemag.org

Published by AAAS
 This Week in Science

Getting the Feel of DNA

To transcribe a gene, RNA polymerase (RNAP) must unwind the promoter DNA to form a “transcrip-
tion bubble” and the RNAP-promoter open complex (RPo). The activity of RPo is critical for the
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mophilus, variously in complex with promoter DNA and an RNA primer. RNAP and σ recognize the
promoter through sequence-specific contacts with transcription-bubble, nontemplate-strand DNA.
Critical interactions occur through the unstacking of DNA bases and their insertion into pockets on
the surfaces of the two proteins, allowing direct sensing of the DNA sequence.
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Double Delivery During

Plant Fertilization
Double fertilization is a defining feature of flowering plants and
involves two nonmotile male gametes (sperm cells) and two
female gametes (egg cell and central cell). Both fertilization
events are necessary for reproductive success. It is not clear how
flowering plants ensure the reliable and on-time fusion of the
two pairs of gametes, while preventing polyspermy. Sprunck
AAAS is here –
preparing minority students
et al. (p. 1093; see the Perspective by Snell) now show that for careers in science.
gamete interactions in Arabidopsis depend on small cysteine-
Part of AAAS’s mission is to diversify and
rich EGG CELL 1 (EC1) proteins that accumulate in storage vesicles of the egg cell and that are released
strengthen the scientific work force. To help
during sperm-egg interaction. EC1 peptides trigger the delivery of a fusogen to the sperm cell surface. achieve this goal, AAAS partners with NSF
An intercellular link connects the two sperm cells throughout the gamete fusion process and could play to present the Historically Black Colleges
a role in preventing the spontaneous fusion of activated sperm cells. and Universities Undergraduate Program,
a conference where students from HBCUs
get experience presenting their research,
Synchronous Brain Activity networking with peers, meeting with
representatives from graduate schools,
Synchronization of neuronal activity across different brain areas varies according to working memory and learning about career opportunities.
load or the locus of attention. It is thought that synchronization serves as a general mechanism for If you’re not yet a AAAS member, join us.
CREDIT: STEFANIE SPRUNCK

Together we can make a difference.

increasing effective cross-area communication during memory and attention tasks. However, it is
not known if synchronization carries specific content. Salazar et al. (p. 1097, published online 1
To learn more, visit
November) recorded from multiple electrodes across parietal and prefrontal cortices of monkeys and aaas.org/plusyou/hbcuup
found content-specific synchronization for both location and object identity in a working memory task.
The findings suggest that the contents of working memory could be maintained through site-specific
synchrony across brain areas.

www.sciencemag.org SCIENCE VOL 338 23 NOVEMBER 2012

Published by AAAS