Articles in 2009

The authors used de novo protein design to generate a simple unnatural oxygen transport protein, akin to human neuroglobin; the design strategy involved the assembly of a short helix-forming sequence into a four-helix bundle that contained histidine residues at key positions. The O₂ on-rate, off-rate and dissociation constants are similar to those of human neuroglobin and other naturally occurring globins.

One of two papers identifying distinct clusters of neurons in the Johnston's organ, a structure from the fruitfly antenna previously associated with courtship song detection, that specifically respond either to continuous deflections of the antenna, as provoked by wind or gravity, or to vibrating stimuli such as sounds. The segregation of different mechanosensation modalities through separate neuronal pathways in one organ is reminiscent of the hearing and vestibular system division of mammals.

The authors show that mouse or human tumours in which the PI3K/Akt pathway is constitutively activated are resistant to dietary restriction whereas other tumours are sensitive. The authors also implicate the Akt target gene FOXO1 in the response to dietary restriction.

This paper presents the first X-ray structure of a member of the the betaine/choline/carnitine transporter family. This Na⁺-coupled symporter (BetP) has the same overall fold as other unrelated Na⁺-coupled transporters and is captured in an intermediate conformation, whereby the substrate (glycine betaine) is occluded from both sides of the membrane.

Rho signalling is shown to regulate angiogenesis in response to mechanical signals such as extracellular matrix elasticity, or the angiogenic factor VEGF. The pathway modulates the antagonistic functions of two transcription factors, TFII-I and GATA2, which regulate the expression of VEGFR2.

An analysis of the last deglaciation shows that the South Atlantic cooled essentially instantaneously with warming in the North Atlantic. This first concrete evidence of an immediate seesaw connection provides a link between the rapid warming in the North Atlantic and the more gradual Antarctic response.

This study has reconstituted membrane invagination and scission in vitro using purified endosomal sorting complex required for transport (ESCRT)-III subunits and giant unilamellar vesicles. Snf7 is important for membrane scission whereas the ATPase Vps4 is required for recycling ESCRT-III proteins for further rounds of membrane budding.

The protein tyrosine phosphatase EYA is shown to be recruited to DNA double-strand breaks after genotoxic stress and to remove a tyrosine phosphorylation modification on histone H2AX. The tyrosine phosphorylation state of H2AX helps to determine whether DNA repair or pro-apoptotic factors are recruited to chromatin, with tyrosine dephosphorylation by EYA promoting repair rather than apoptosis.

Retrovirus capsids are polymorphic, consisting of variable hexamer and pentamer aggregates that are thought to reflect fullerenes. This paper reports the cryo-electron microscopy analysis of RSV capsid protein visualizing pentamers, and confirms that retrovirus capsid has a fullerene-based architecture.

Determining the spatial and temporal activity patterns of enhancers remains a challenge in the functional annotation of the human genome. In this study, the genome-wide occupancy of the enhancer-associated protein p300 was determined in developing mouse tissues by using chromatin immunoprecipitation followed by massively parallel sequencing. Testing the p300-bound sequences in a transgenic mouse enhancer assay confirmed that p300 binding is a highly effective means to identify enhancers and to predict in which tissues they are active.

L-form cells can derive from various bacterial species and do not possess a cell wall. It is shown that Bacillus subtilis can convert into L-form through a single point mutation, and that B. subtilus L-form cells are able to propagate independent of FtsZ, an essential component of the bacterial cell division machinery.

Sorghum is an African grass that is grown for food, animal feed and fuel. The current paper presents an initial analysis of the ∼730 megabase genome of Sorghum bicolor. Genome analysis and its comparison with maize and rice shed light on grass genome evolution and also provide insights into the evolution of C₄ photosynthesis, as well as protein coding genes and miRNAs that might contribute to sorghum's drought tolerance.

Actin exists in two forms in cells. Monomeric globular actin (G-actin) polymerizes to form filamentous actin (F-actin), which drives several processes such as cell motility. This paper presents a high resolution structure of F-actin and describes the differences between the conformations of the two forms of actin.

Variations in the seasonal cycle of temperatures at the Earth's surface are spatially mapped on both land and sea, and trends in the recent past (1954–2007) are compared with those occurring earlier (1900–1954). Assuming that the earlier part of the temperature record is dominated by natural variations, the recent trends seem highly anomalous: temperatures on land show a shift to earlier seasons by 1.7 days, and the amplitude of the cycle has decreased in this period.

A range of plastic semiconductors have been developed that have the combination of physical and chemical properties required to enable printable electronic circuitry, but these are almost exclusively 'hole transporting' materials. If an electron-transporting equivalent could be found, it could be combined with the existing classes of materials to produce yet more powerful devices. This paper reports the development of a such a material: the electron-transporting plastic semiconductor exhibits unprecedented device performance, and is compatible with a broad range of printing and processing technologies.

Recent evidence has suggested the existence of immunological memory in natural killer (NK) cells. This paper confirms and extends the earlier observation, providing direct evidence that memory NK cells are more effective than naive NK cells in controlling viral infection in vivo.

A ring ATPase from a bacteriophage, ϕ29, helps load the dsDNA genome into the viral shell. It is shown that this motor packages the DNA in 10 base pair (bp) bursts, which are composed of four individual 2.5 bp steps, each representing hydrolysis of a single ATP. Such a non-integral step size is unexpected, and raises intriguing mechanistic questions about ATP hydrolysis within rings.

After expression of the PML–RAR oncogene in haematopoietic stem cells, p21 is necessary to limit cell cycle progression and thus limit the accumulation of DNA damage which would otherwise limit the self-renewal of leukaemic stem cells and prevent the development of leukaemia