Viral sponges sequester nucleotide signals to inactivate immunity

Bacteria synthesize specialized nucleotide signals to control anti-phage defense. Two papers – by Huiting et al. and Jenson et al. – now reveal that bacteriophages encode protein ‘sponges’ that sequester cyclic oligonucleotide immune signals and inactivate host antiviral immunity.     

Feeding the world sustainably: efficient nitrogen use

Globally, overuse of nitrogen (N) fertilizers in croplands is causing severe environmental pollution. In this context, Gu et al. suggest environmentally friendly and cost-effective N management practices and Hamani et al. highlight the use of microbial inoculants to improve crop yields, while reducing N-associated environmental pollution and N-fertilizer use.     

Dual function of the CHS3-CSA1 immune receptor pair

Plant nucleotide-binding leucine-rich repeat (NLR) receptors mediate specific recognition of pathogen effectors to initiate effector-triggered immunity. Recently, studies by Schulze et al., Yang et al., and Gu et al. collectively show that the Arabidopsis (Arabidopsis thaliana) NLR pair CHS3-CSA1 acts through two distinct activation modes to recognize different pathogen effectors, thus revealing the dual function of the CHS3-CSA1 pair in plant disease resistance.     

Protein circuit design using de novo proteins

Protein-based biological circuits enable customized control of cellular functions, and de novo protein design enables circuit functionalities that are not possible by repurposing natural proteins. Here, I highlight recent progress in protein circuit design, including CHOMP, developed by Gao et al., and SPOC, developed by Fink et al.     

pH regulates peptide–receptor perception

Diverse plant small peptides are perceived by their corresponding receptors to mediate local or long-distance intercellular communications in various developmental and adaptive programs; notably, the mechanisms of peptide–receptor perception remain largely unrevealed. Two reports (Liu et al.; Diaz-Ardila et al.) shed light on how pH regulates peptide–receptor perception.     

Senescent cell: the ‘factory of viral amplification’

It has been demonstrated that reactivation of endogenous retroviruses (ERVs), the remnants of ancient retroviral infection, participate in various physiological and pathological conditions. Liu et al. recently showed us very interesting findings that aberrant expression of ERVs, induced by epigenetic alterations, accelerates cellular senescence.     

Endoreplication controls cell size via mechanochemical signaling

During hypocotyl development, an asymmetric auxin gradient causes differential cell elongation, leading to tissue bending and apical hook formation. Recently, Ma et al. identified a molecular pathway that links auxin with endoreplication and cell size through cell wall integrity sensing, cell wall remodeling, and regulation of cell wall stiffness.     

Naturally engineered plant microbiomes in resource-limited ecosystems

Nature-designed plant microbiomes may offer solutions to improve crop production and ecosystem restoration in less than optimum environments. Through a full exploration of metagenomic data, Camargo et al. showed that a previously unknown microbial diversity enhances nutrient mobilization in stress-adapted plants.     

Spore germination receptors – a new paradigm

David Rudner and his team (Gao et al.) predict a pentameric structure for the GerA alanine-responsive germination receptor of Bacillus subtilis and demonstrate that it behaves as a nutrient-gated ion channel, finally establishing a function for this novel family of receptors and focussing research on early ion movements in germination.     

Bear essentials

Strangely, American black bears come in many colours. New work by Puckett et al. shows that a missense alteration in the gene encoding tyrosinase-related protein 1 (TYRP1) likely interferes with melanin synthesis and is responsible for the cinnamon colour variant in the southwest USA. However, the adaptive significance of colour polymorphisms in this large carnivore remains opaque.     

Vertebrate–arthropod communication dictates tick development and pathogen transmission

Cross-species communication drives the coordination of diverse biological processes in complex systems. Rana et al. discovered that Ixodes scapularis, the tick vector of Lyme disease, produces a receptor that binds host interferon-gamma (IFNγ) in the blood meal, which orchestrates tick development, immunity, and vector competence.     

Actin finally matures: uncovering machinery and impact

Actin, one of the most abundant proteins in nature and a key component of the cytoskeleton, undergoes a unique multistep N-terminal (Nt) maturation. In a recent report, Haahr et al. identified actin maturation protease (ACTMAP) as the dedicated actin aminopeptidase and showed that its absence is associated with abnormal muscle physiology.     

Actin subversion for productive Plasmodium hepatocyte invasion

Productive invasion of hepatocytes by Plasmodium sporozoites is a key step of infection. The parasites traverse hepatocytes before targeting one of them to form a parasitophorous vacuole for parasite expansion. Schepis et al. show the induction of membrane ruffling via host Rho GTPases by Plasmodium sporozoites facilitating productive invasion.     

Staying vigilant: NLR monitors virus invasion

Phytohormones play important roles in plant immunity. Recently, Chen et al. discovered that the tomato spotted wilt virus attacks the plant hormone receptor to promote infection. Plants evolved an immune receptor to mimic the attacked hormone receptors to recognize the virus, thereby activating a robust immune response.     

Membrane lipid composition defines membrane protein spectrum

In addition to glycerophospholipids, bacterial membranes often include amino acid-containing acyloxyacyl lipids. The functional implications of these aminolipids are largely unknown. However, a recent study by Stirrup et al. expands our understanding and shows that they are major determinants for membrane properties and the relative abundance of distinct membrane proteins in bacterial membranes.     

Sense the moist and feel the heat: mosquito host and oviposition site detection

Laursen et al. identified coreceptor Ir93a that is required for humidity and thermal sensing in the mosquito species Anopheles gambiae and Aedes aegypti. Behavioural studies with mutant mosquitoes with disrupted Ir93a revealed that they were less attracted to a blood meal source and oviposition site at close distance.     

Liver-stage Plasmodium infection tunes clinical outcomes

Chora and colleagues show that infection of the liver by Plasmodium modulates severity of disease in the experimental cerebral malaria (ECM) model by generating gamma delta (ɣδ) T cells that produce IL-17. This work calls into question the long-standing assumption that liver infection does not modulate severity of malaria.     

Chemical constituents from Valeriana jatamansi

Phytochemical study of Valeriana jatamansi Jones afforded 45 compounds, including twenty-three iridoids (1–23), five sesquiterpenes (24–28), three steroids (29–31) and fourteen lignins (32–45). The structures of these compounds were assigned by detailed interpretation of spectroscopic data (1D and 2D NMR, HRESIMS) and comparisons with the published data. This is the first report of isolation of compounds (1–6, 10, 21, 25, 41, 43, 44, 45) from Valerianaceae, compounds (13, 27, 39) within the genus Valeriana and compound 30 from V. jatamans. The chemotaxonomic data can support the genus Valeriana being accepted as a member of transitional taxa between the family Valerianaceae and Caprifoliaceae.