2020

The respiratory complexes located in the inner membranes of our mitochondria are true macromolecular batteries: they couple the flow of electrons through a wire of metal clusters and co-factors with proton transfer to create a gradient that provides the energy needed to produce ATP and thus power the essential processes of life. The first complex in the respiratory chain, called Complex I, is one of the largest membrane proteins, composed of 45 subunits. The processes involved in assembly of (…)

Microbial rhodopsins constitute a large and diverse superfamily of light-sensitive membrane proteins. They play a major role in solar energy capture in the sea, utilizing it to perform ion translocation, sensory, enzymatic, and other activities. Microbial rhodopsins also found essential applications in medicine in neuroscience, being the core of optogenetics - biotechnology for optical control on living cells and tissues. Our group studies the functional and structural properties of new (…)

The human mitochondrial proteome is estimated to contain more than a thousand proteins, 99% of which are synthesized outside the mitochondria. These proteins are imported inside the mitochondria in very specific places, in one of the membranes, in the inter-membrane space or in the matrix. The molecular mechanisms of this protein import are still poorly understood at the atomic level. A study by the NMR group has shed light on the mechanistic basis of the specificity of the chaperone system (…)

Unlike eukaryotes, which have their genetic material within a nucleus, bacterial DNA is now known to be rather packed in diffuse, but not random, regions called nucleotides. But how are they organized? HU is an important, even essential, protein in some bacterial nucleotides. However, the cellular function of HU in DNA compaction has been controversial practically since its identification in the 1970s, notably because of its different behavior from one species to another. The AFM team of the (…)

The EUROMAR committee awarded the Varian Young Investigator prize to Paul Schanda (IBS/NMR). This prestigious award was created in honour of Russel Varian, a pioneer in NMR spectroscopy, to recognize a single investigator within the first 12 years of his/her independent career, for achievements in any area of magnetic resonance. This award recognises Paul Schanda’s methodological developments to characterise the dynamics and structure of proteins in solid and liquid states. Some of the (…)

Our activities are maintained subject to organizational adjustments: people involved in laboratory-based research activity work on site but teleworking is maximised whenever possible. Staff on site are reminded to respect strictly sanitary measures and reduce social interactions. All scientific events such as meetings and seminars are hold online.

Glycoprotein S, located on the SARS-CoV-2 virus membrane, is known to allow the entry of this virus into human cells via the ACE2 receptor, present on the surface of infected cells. The Membrane & Pathogens group, in collaboration with IBS/IRPAS and MEM groups and groups from Spain and Italy, have discovered that C-type lectin receptors (CLRS) of antigen-presenting cells are involved in the overall infection process. DC-SIGN, L-SIGN, Langerin and MGL bind to diverse glycans of the (…)

Bunyavirales is an order of segmented negative-strand RNA viruses comprising several life-threatening human pathogens for which there is currently no treatment (La Crosse virus, Hantaan virus, Crimean Congo virus, Lassa virus). The replication and transcription of their genome are essential steps of their viral cycle and are catalyzed by a key viral enzyme: the RNA-dependent RNA polymerase. The MEM group at IBS, in collaboration with Dr. Cusack’s group at EMBL Grenoble, describes here the (…)

Protein aggregation into amyloid superstructures is the molecular manifestation of a large variety of neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Evidence is increasing that transient on-pathway oligomers are actually the toxic species, such that time-resolved monitoring of protein aggregation is highly desirable. Whereas time-resolved structural techniques have been developed and applied to study protein aggregation, methods accessing protein center-of-mass and internal (…)

Hélène Malet, Associate Professor at the University Grenoble Alpes and research scientist in Dr. Guy Schoehn’s Methods and Electron Microscopy group at IBS, is appointed Junior Member of the Institut Universitaire de France (IUF) from October 1, 2020 for a period of five years. Viral replication and transcription are key steps of the viral cycle. Hélène Malet analyses the structure of viral proteins involved in these processes, in particular viral polymerases. During her thesis, carried (…)

IBS ​Researchers, in collaboration with EMBL Grenoble, have used NMR to reveal the molecular mechanisms that support the adaptation of avian influenza virus from birds to humans. In birds, the avian influenza virus acts via the interaction of its polymerase with a key transcription factor: ANP32A. Two regions of these highly dynamic molecules seemed to be strongly implicated, but the molecular basis of the interaction remained unknown, preventing researchers from understanding how certain (…)

A new microfabrication process, developed by the IBS Synchrotron group, in collaboration with LOF Bordeaux, enables the integration of regenerated cellulose dialysis membranes between two layers of the microchip, therefore proposing a robust and inexpensive way to fabricate polyvalent microchips. They cover the whole process, from the crystal growth on chip with the desired properties (size, number, crystal quality) by the micro-dialysis method, to the in situ X-ray diffraction experiments (…)

The capsule is the dominant Streptococcus pneumoniae virulence factor, yet how variation in capsule thickness is regulated is poorly understood. Here, IBs researchers, in collaboration with researchers from UCL Medical School, St George’s University of London and Leceister University, describe an unexpected relationship between mutation of adcAII, which encodes a zinc uptake lipoprotein, and capsule thickness. Mutation of adcAII resulted in a striking hyperencapsulated phenotype, increased (…)

The possibility of photoconvertible fluorescent proteins (PCFPs) to convert from a green- to a red-emitting state is widely used in single-molecule localization microscopy. However, single-molecule imaging is highly disturbed by ‘blinking’ (ie transient loss of fluorescence), which is a consequence of individual PCFPs visiting « dark states ». Blinking has generally been described in the photoconverted red state, but in this paper, we focused on green-state blinking. In a collaboration (…)

The biological cofactor nicotinamide adenine dinucleotide (NAD) is involved in many central metabolic reactions involving the transfer of one proton and two electrons. Depending of the organism, its precursor quinolinic acid (QA) is synthesized from tryptophan (like in humans) or from the condensation of dihydroxyacetone phosphate and iminoaspartate (in bacteria). The latter reaction, which is probably the oldest way to make QA, is catalyzed by the highly versatile enzyme NadA. Indeed, (…)

Nitrogenase, a key player in the global nitrogen cycle, catalyzes the reduction of atmospheric N2 to 2 NH3 at ambient temperature and normal pressure. Its active site, also designated FeMo-cofactor, corresponds to a [MoFe7S9C-(R)-homocitrate] species, whose biosynthesis and insertion requires the action of over a dozen accessory proteins provided by the NIF (for NItrogen Fixation) assembly machinery. Among them, the radical S-adenosyl-L-methionine protein NifB plays an essential role, (…)

Light-driven Na+ pump KR2 is microbial rhodopsin found in marine bacteria in 2013. Its unique ability to actively transport Na+, but not K+, Ca2+, and H+, makes the protein a perspective tool for optogenetics – the biotechnological method for precise and minimally-invasive optical control of the living matter. The molecular mechanism of light-driven Na+ pumping has not yet been known, as the existing 3D structures of the KR2 were limited only to its inactive, ground state. The researchers (…)

The IBS re-opens step by step from 25 May Following the french government’s announcement to lift coronavirus lockdown, the gradual reopening of the IBS is being organised in accordance with all safety measures and regulations recommended by our operating agencies. The IBS re-opens step by step from 25 May and should reach a level of about 50% physical presence on site after 4 weeks. It implies that part of your contacts are still teleworking and may be reached by email (to know more). IBS (…)

Noncoding RNAs accomplish a remarkable variety of biological functions. From the regulation of gene expression to translation and even the protection of genomes from foreign nucleic acids. Among them, long non-coding RNA (lncRNA) are regulating RNAs of large size (> 1000 nucleotides) that are involded in disease prevention but their function as well as three-dimensional structures remain poorly characterized. A recent study has demonstrated the role of local structural elements of the (…)

The IBS pays tribute to Jean-Luc Ferrer who passed away on April 21st, 2020 in his 55th year, after a long battle against the illness. He was a real pillar of the French CRG lines at ESRF, and an internationally recognized scientist in the field of structural biology. After graduating from the Ecole Centrale Paris as an engineer in 1987, Jean-Luc Ferrer performed a DEA in Physical Chemistry at the University Paris VI, and in 1990 he obtained his PhD in Physics, which was carried out at the (…)