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The identification of a transport mechanism for boron in plant roots provides a surprising connection with transport systems in other, very different settings, such as the kidney.

As bacteria become resistant to existing drugs, there is a need for antibiotics with new modes of action. Such a compound has been found, and it works by binding to an intermediate in the catalytic cycle of its target.

Venkei et al. show that Y-linked Su(Ste) piRNAs are produced via 5′-to-3′ phased-biogenesis initiated by maternally deposited 1360/Hoppel-derived piRNAs, leading to silencing of Ste in the male germline.

Insights on the mechanistic differences between artificial metalloenzymes (ArMs) with non-native metal centres and the free cofactor or natural enzymes are scarce. Now, a detailed mechanistic analysis of a cyclopropanation reaction catalysed by such an ArM is provided, revealing intriguing differences to the natural system.

PIWI-interacting RNAs (piRNAs) have numerous crucial biological roles, particularly transposon silencing in the germ line. In this Review, the authors describe our latest understanding of piRNA biogenesis and functions across diverse species, highlighting how, despite the universal importance of transposon control, different species have evolved intriguingly distinct mechanistic routes to achieve this.

Fusion proteins between roGFP2 and glutaredoxins are used for intracellular redox measurements. Here, the authors determined all rate constants of the reaction cycle for roGFP2 measurements and identified an alternative glutaredoxin mechanism.

The widespread presence of somatic PIWI-interacting RNAs targeting transposable elements across the arthropod phylum suggests that this pathway was active in the last common ancestor of arthropods.

Glutaredoxins have important roles in redox processes. Here the authors show that the enzymatic activity of glutaredoxins requires two distinct glutathione interactions sites, one recognizing the glutathione disulfide substrate and one activating glutathione as a reducing agent.

PIWI-interacting RNAs (piRNAs) are ~25–33 nt small RNAs expressed in animal germ cells. Here, the authors develop a single-cell small RNA sequencing method and report that a class of ~20-nt piRNAs lacking 3′ end 2′-O-methylation are associated with PIWIL3 protein and predominantly expressed in human and monkey oocytes.

ELOVLs are membrane-embedded enzymes that elongate very long chain fatty acids, precursors of sphingolipids and ceramides. The first crystal structure of a human ELOVL reveals an unexpected reaction mechanism, suggesting potential approaches for inhibition in disease.

The genome encodes thousands of small RNAs that interact with PIWI proteins; these PIWI-interacting RNAs (piRNAs) mediate silencing of transposable elements and thereby protect the genome. New insights are being gained into the formation and functions of piRNAs, and where they exert their action in the cell.

Although manipulation of objects using light and sound waves is an established technique, it has so far been confined to static environments. Iterative tailoring of acoustic far fields now allows control of objects in disordered and dynamic media.

Ribosome can mediate piRNA biogenesis from long non-coding RNAs following translation of the short open reading frames. Here the authors show that 80S ribosome also guides piRNA production from 3’ UTR of protein-coding genes after translation of long open reading frames, indicating a general piRNA biogenesis mechanism regardless of their precursor ORF length.

Acetylation of histone H3K23 has emerged as an essential posttranslational modification, yet this epigenetic mark remains poorly understood. Here, the authors identify the native MORF complex as a histone H3K23-specific acetyltransferase and show that interaction of the MORF subunit with acylated H3K14 promotes acetylation of H3K23 by this complex to activate transcription.

The formation of C-C bonds in fatty acid and polyketide biosynthesis depends on β-ketoacyl-acyl carrier protein (ACP) synthases (KSs). Here, the authors present structures of E.coli KSs bound to substrate mimetic bearing ACPs, providing insights into the catalytic mechanism underlying C-C bond forming reactions.

Cyclodipeptide synthases hijack aminoacyl tRNAs to produce various cyclic dipeptides—the biosynthetic precursors of several secondary metabolites. Here, the authors solved the crystal structure of a cyclodipeptide synthase bound to a reaction intermediate analogue and provide novel insights into the mechanism of synthesis.

Protein motion is essential for biological processes like enzyme function. Here the authors report the time-resolved protein structures captured during catalysis of copper amine oxidase using mix-and-inject serial femtosecond X-ray crystallography.

Rastermap is an analysis method for exploring dynamical and spatial relationships among hundreds to hundreds of thousands of neurons. The algorithm uses a fast optimization technique to discover complex neural patterns, such as sequences.

Analyses of consummatory reproductive behaviours in male mice uncover a brain mechanism whereby an internal state can attribute a social quality to a generic touch to initiate purposeful reproductive actions.

Bacterial Type I polyketide synthases are responsible for producing both lifesaving medicines and virulence factors, yet their stepwise mechanism remains elusive. Here, Burkart et al. characterize acyl carrier protein bound states of mycocerosic acid synthase from Mycobacterium tuberculosis through crosslinking and cryo-EM.

Here, the authors identify and characterize three gut bacterial enzyme families that metabolize endogenous and synthetic steroid hormones, showing to act on diverse substrates, to exhibit gene fusions, and gender-linked prevalence, opening avenues for studying mechanisms of microbial-mediated steroid metabolism and host hormonal physiology.

Recent progress in high-throughput sequencing has uncovered an astounding landscape of small RNAs in eukaryotic cells. Various small RNAs can be classified into three classes based on their biogenesis mechanism and the type of Argonaute protein that they are associated with.

A deterministic violation of the Bell inequality is reported between two superconducting circuits, providing a necessary test for establishing strong enough quantum entanglement to achieve secure quantum communications.

A mechanism for creating patterns of iridescent structural colour by total internal reflection of light beams along a concave optical interface leading to interference is described, for complex microscopic systems and for systems as simple as condensed water drops.

24-nt phased siRNA (phasiRNA) regulate reproduction in grasses, yet are absent from Arabidopsis, and were thought to be monocot-specific. Here, Xia et al. show that 24-nt phasiRNAs are in fact broadly distributed among eudicots and are consistently enriched during meiosis, despite possibly arising from distinct biogenesis pathways.

A paramutation occurs between two alleles in the same locus, when one allele induces a heritable mutation in another allele without modifying the DNA sequence; now, in Drosophila, a paramutation is shown to be transmissible over generations.

Neural mechanisms mediating information flow and processing in dendrites are not fully understood. Here the authors developed techniques to map bioelectrical excitations in the dendrites of neurons in acute slices of mouse brain tissue. They developed a holistic picture of the roles of dendritic excitations in spike back-propagation.

Functional catalytic triads have been designed into a hyperstable heptameric α-helical barrel protein. Twenty-one mutations were introduced to form seven Cys-His-Glu catalytic triads. The resulting protein hydrolyses p-nitrophenyl acetate with activities matching the most-efficient redesigned hydrolases based on natural protein scaffolds. This is the first example of a functional catalytic triad being engineered into a fully de novo protein.

Many new small RNA species and their derived fragments have been recently identified in animals. This Review discusses the biogenesis and functions of both structural small RNAs, such as tRNAs and small nuclear RNAs (snRNAs), and of regulatory small RNAs such as microRNAs and PIWI-interacting RNAs (piRNAs).

This study proposes an unreported molecular mechanism of substrate inhibition in enzymes. It shows that a competitive inhibitor reduces substrate inhibition and identifies unique enzyme-substrate complexes, suggesting an unreported paradigm for enzyme regulation.

Polyketide synthases make use of a limited set of enzymes to create diverse natural products. The discovery that a ketosynthase homolog catalyzes ester bond formation instead of the typical Claisen condensation uncovers a previously unknown mechanism to generate chemical diversity.

Levantine Phoenicians made little genetic contribution to Punic settlements in the central and western Mediterranean between the sixth and second centuries bce; instead, the Punic people derived most of their ancestry from a genetic profile similar to that of Sicily and the Aegean, with notable contributions from North Africa as well.

Piwi proteins bind a class of small germline RNAs, called piRNAs, whose biogenesis and functions are largely unknown. High-throughput sequencing after cross-linking and immunoprecipitation (HITS-CLIP) analysis in combination with RNA sequencing to analyze the genome-wide RNA target repertoire of mouse Piwi (Miwi) proteins in testis uncovers the in vivo piRNA biogenesis pathway and demonstrates that Miwi binds spermiogenic RNAs directly without using piRNAs as guides.

Insight into the algorithmic form and learning principles underlying cognitive maps in the hippocampus is provided.

Soybean is an important crop plant, providing seed protein and oil and fixing atmospheric nitrogen through symbioses with soil-borne microorganisms. Using a whole-genome shotgun approach, its 1.1-gigabase genome is now sequenced and integrated with physical and high-density genetic maps to create a chromosome-scale draft sequence assembly.

CRISPR–Cas-mediated genome, epigenome and transcriptome engineering in crops is crucial as the human population grows and climate deteriorates. This Review discusses new CRISPR–Cas tools for precise engineering, and their uses in improving crop traits such as yield and tolerance to climate stresses.

Cyclodipeptide synthases use amino acid–loaded tRNAs as substrates to form cyclic peptide dimers. Biochemical and bioinformatic analyses now show that these enzymes are distributed into two phylogenetically distinct major subfamilies and use a broad range of substrates that can be predicted with newly defined sequence motifs.

Here the authors present the cryo-EM structure of active and inhibited human MTHFR, revealing a dynamic inhibitory mechanism dependent on dual SAM binding. The resulting closed conformation features an autoinhibitory element effectively blocking enzymatic activity.

Pachytene piRNAs are abundant piRNAs in mammalian adult testes but their biogenesis pathway is not fully understood. Here, the authors identify TDRD5 as a piRNA biogenesis factor in mice, showing that it binds piRNA precursors and promotes pachytene piRNA production from specific transcript regions.

Lysine ubiquitination, catalysed by E3 ubiquitin ligases, is pivotal for regulating protein stability and cell signalling. Using protein semisynthesis, the roles of the C-terminal carboxylate and conformational interconversion in HECT-domain E3 catalysis are now characterized, revealing evolutionary plasticity in side chain versus backbone utilization.

Flies use master lists of DNA sequences from transposons to identify and silence these virus-like, genomic parasites. How the lists themselves escape the fate of their transposon targets has now been solved. See Letter p.54