Intronic ATTTC repeat expansions in STARD7 in familial adult myoclonic epilepsy linked to chromosome 2

Familial Adult Myoclonic Epilepsy (FAME) is characterised by cortical myoclonic tremor usually from the second decade of life and overt myoclonic or generalised tonic-clonic seizures. Four independent loci have been implicated in FAME on chromosomes (chr) 2, 3, 5 and 8. Using whole genome sequencing and repeat primed PCR, we provide evidence that chr2-linked FAME (FAME2) is caused by an expansion of an ATTTC pentamer within the first intron of STARD7. The ATTTC expansions segregate in 158/158 individuals typically affected by FAME from 22 pedigrees including 16 previously reported families recruited worldwide. RNA sequencing from patient derived fibroblasts shows no accumulation of the AUUUU or AUUUC repeat sequences and STARD7 gene expression is not affected. These data, in combination with other genes bearing similar mutations that have been implicated in FAME, suggest ATTTC expansions may cause this disorder, irrespective of the genomic locus involvedSupplementary Information: Supplementary Data 1; Supplementary Data 2; Reporting Summary.NHMRC; Women’s and Children’s Hospital Research Foundation; Muir Maxwell Trust; Epilepsy Society; The European Fund for Regional Development; The province of Friesland, Dystonia Medical Research Foundation; Stichting Wetenschapsfonds Dystonie Vereniging; Fonds Psychische Gezondheid; Phelps Stichting; The Italian Ministry of Health; Istituto Superiore di Sanità, Italy; Undiagnosed Disease Network Italy; The Fondation maladies rares, University Hospital Essen and UK Department of Health’s NIHR.https://www.nature.com/ncommspm2020Neurolog

How Do They Do It? – Understanding the Success of Marine Invasive Species

From the depths of the oceans to the shallow estuaries and wetlands of our coasts, organisms of the marine environment are teeming with unique adaptations to cope with a multitude of varying environmental conditions. With millions of years and a vast volume of water to call their home, they have become quite adept at developing specialized and unique techniques for survival and – given increasing human mediated transport – biological invasions. A growing world human population and a global economy drives the transportation of goods across the oceans and with them invasive species via ballast water and attached to ship hulls. In any given 24-hour period, there are about 10,000 species being transported across different biogeographic regions. If any of them manage to take hold and establish a range in an exotic habitat, the implications for local ecosystems can be costly. This review on marine invasions highlights trends among successful non-indigenous species (NIS), from vectors of transport to ecological and physiological plasticity. Apart from summarizing patterns of successful invasions, it discusses the implications of how successfully established NIS impact the local environment, economy and human health. Finally, it looks to the future and discusses what questions need to be addressed and what models can tell us about what the outlook on future marine invasions is

A de novo metalloenzyme for cerium photoredox catalysis

Cerium photoredox catalysis has emerged as a powerful strategy to activate molecules under mild conditions. Radical intermediates are formed using visible light and simple complexes of the earth-abundant lanthanide. However, it remains a major challenge to achieve stereocontrol in these reactions. Here, we report an artificial photoenzyme enabling this chemistry inside a protein. We utilize a de novo designed protein scaffold that tightly binds lanthanide ions in its central cavity. Upon visible-light irradiation, the cerium-dependent enzyme catalyzes the radical C–C bond cleavage of 1,2-diols in aqueous solution. Protein engineering led to variants with improved photostability and initial stereoselectivity. The photoenzyme cleaves a range of aromatic and aliphatic substrates, including lignin surrogates. Surface display of the protein scaffold on E. coli facilitates whole-cell photobiocatalysis. Furthermore, we show that also natural lanthanide-binding proteins are suitable for this approach. Our study thus demonstrates a new-to-nature enzymatic photoredox activity with broad catalytic potential

High-resolution structures of the M2 channel from influenza A virus reveal dynamic pathways for proton stabilization and transduction

SignificanceThe conduction of protons through the highly restricted paths of transmembrane proteins is an essential process of living systems and an intriguing problem in modern physical chemistry. The small size of the influenza M2 proton channel makes it an ideal system for the study of proton transport across a membrane. Additionally, the M2 channel has medical relevance as an anti-flu drug target. These high-resolution structures of the channel were obtained by crystallizing the protein in a membrane-like environment and reveal networks of hydrogen-bonded waters that change with temperature and pH. The locations of these waters, in conjunction with molecular dynamics simulations that predict their hydrogen bond orientations, provide insight into the mechanism of proton stabilization and transduction within the channel.The matrix 2 (M2) protein from influenza A virus is a proton channel that uses His37 as a selectivity filter. Here we report high-resolution (1.10 Å) cryogenic crystallographic structures of the transmembrane domain of M2 at low and high pH. These structures reveal that waters within the pore form hydrogen-bonded networks or “water wires” spanning 17 Å from the channel entrance to His37. Pore-lining carbonyl groups are well situated to stabilize hydronium via second-shell interactions involving bridging water molecules. In addition, room temperature crystallographic structures indicate that water becomes increasingly fluid with increasing temperature and decreasing pH, despite the higher electrostatic field. Complementary molecular dynamics simulations reveal a collective switch of hydrogen bond orientations that can contribute to the directionality of proton flux as His37 is dynamically protonated and deprotonated in the conduction cycle

Structural and Functional Analysis of Hepatitis C Virus Strain JFH1 Polymerase▿

The hepatitis C virus (HCV) isolate JFH1 represents the only cloned wild-type sequence capable of efficient replication in cell culture, as well as in chimpanzees. Previous reports have pointed to the viral polymerase NS5B as a major determinant for efficient replication of this isolate. To understand the underlying mechanisms, we expressed and purified NS5B of JFH1 and of the closely related isolate J6, which replicates below the limit of detection in cell culture. The JFH1 enzyme exhibited a 5- to 10-fold-higher specific activity in vitro, consistent with the polymerase activity itself contributing to efficient replication of JFH1. The higher in vitro activity of the JFH1 enzyme was not due to increased RNA binding, elongation rate, or processivity of the polymerase but to higher initiation efficiency. By using homopolymeric and heteropolymeric templates, we found that purified JFH1 NS5B was significantly more efficient in de novo initiation of RNA synthesis than the J6 counterpart, particularly at low GTP concentrations, probably representing an important prerequisite for the rapid replication kinetics of JFH1. Furthermore, we solved the crystal structure of JFH1 NS5B, which displays a very closed conformation that is expected to facilitate de novo initiation. Structural analysis shows that this closed conformation is stabilized by a sprinkle of substitutions that together promote extra hydrophobic interactions between the subdomains “thumb” and “fingers.” These analyses provide deeper insights into the initiation of HCV RNA synthesis and might help to establish more efficient cell culture models for HCV using alternative isolates

High-resolution structures of the M2 channel from influenza A virus reveal dynamic pathways for proton stabilization and transduction

SignificanceThe conduction of protons through the highly restricted paths of transmembrane proteins is an essential process of living systems and an intriguing problem in modern physical chemistry. The small size of the influenza M2 proton channel makes it an ideal system for the study of proton transport across a membrane. Additionally, the M2 channel has medical relevance as an anti-flu drug target. These high-resolution structures of the channel were obtained by crystallizing the protein in a membrane-like environment and reveal networks of hydrogen-bonded waters that change with temperature and pH. The locations of these waters, in conjunction with molecular dynamics simulations that predict their hydrogen bond orientations, provide insight into the mechanism of proton stabilization and transduction within the channel.The matrix 2 (M2) protein from influenza A virus is a proton channel that uses His37 as a selectivity filter. Here we report high-resolution (1.10 Å) cryogenic crystallographic structures of the transmembrane domain of M2 at low and high pH. These structures reveal that waters within the pore form hydrogen-bonded networks or “water wires” spanning 17 Å from the channel entrance to His37. Pore-lining carbonyl groups are well situated to stabilize hydronium via second-shell interactions involving bridging water molecules. In addition, room temperature crystallographic structures indicate that water becomes increasingly fluid with increasing temperature and decreasing pH, despite the higher electrostatic field. Complementary molecular dynamics simulations reveal a collective switch of hydrogen bond orientations that can contribute to the directionality of proton flux as His37 is dynamically protonated and deprotonated in the conduction cycle