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Kai Johnsson

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Related publications (125)

Kinetic and Structural Characterization of the Self-Labeling Protein Tags HaloTag7, SNAP-tag, and CLIP-tag

Kai Johnsson, Julien Hiblot, Iuliia Karpenko

The self-labeling protein tags (SLPs) HaloTag7, SNAP-tag, and CLIP-tag allow the covalent labeling of fusion proteins with synthetic molecules for applications in bioimaging and biotechnology. To guide the selection of an SLP-substrate pair and provide gui ...

AMER CHEMICAL SOC2021

Systematic Tuning of Rhodamine Spirocyclization for Super-resolution Microscopy

Kai Johnsson, Lu Wang

Rhodamines are the most important class of fluorophores for applications in live-cell fluorescence microscopy. This is mainly because rhodamines exist in a dynamic equilibrium between a fluorescent zwitterion and a nonfluorescent but cell-permeable spirocy ...

AMER CHEMICAL SOC2021

A general strategy to develop cell permeable and fluorogenic probes for multicolour nanoscopy

Kai Johnsson, Lin Xue, Lu Wang

It is difficult to develop suitable fluorescent probes for live-cell nanoscopy, but a general strategy is now reported that can transform regular fluorophores into fluorogenic probes with excellent cell permeability and low unspecific background signals. U ...

NATURE PUBLISHING GROUP2020

Chemogenetic Control of Nanobodies

Kai Johnsson, Julien Hiblot, Helen Rebecca Ostlund Farrants

Engineered nanobody allows reversible control of activity in cells through the binding of small molecules. ...

NATURE PUBLISHING GROUP2020

6,11-Dioxobenzo[f]pyrido[1,2-a]indoles Kill Mycobacterium tuberculosis by Targeting Iron-Sulfur Protein Rv0338c (IspQ), A Putative Redox Sensor

Kai Johnsson, Stewart Cole, Monica Rengifo Gonzalez, Edina Rita Székely, Andrej Benjak, Jérémie Piton

Screening of a diversity-oriented compound library led to the identification of two 6,11-dioxobenzo[f]pyrido[1,2-a]indoles (DBPI) that displayed low micromolar bactericidal activity against the Erdman strain of Mycobacterium tuberculosis in vitro. The acti ...

AMER CHEMICAL SOC2020

Activatable fluorescent probes for hydrolase enzymes based on coumarin-hemicyanine hybrid fluorophores with large Stokes shifts

Kai Johnsson, Mako Kamiya

We show that the equilibrium of intramolecular spirocyclization of coumarin-hemicyanine hybrid fluorophores can be finely tuned by means of chemical modifications. We used this scaffold to develop activatable fluorescent probes with large Stokes shifts for ...

Royal Society of Chemistry2020

Environmentally Sensitive Color-Shifting Fluorophores for Bioimaging

Kai Johnsson, Julien Hiblot

We introduce color-shifting fluorophores that reversibly switch between a green and red fluorescent form through intramolecular spirocyclization. The equilibrium of the spirocyclization is environmentally sensitive and can be directly measured by determini ...

Wiley-VCH Verlag GmbH2020

SLC25A51 is a mammalian mitochondrial NAD(+) transporter

Kai Johnsson, Liang Wang

Mitochondria require nicotinamide adenine dinucleotide (NAD(+)) to carry out the fundamental processes that fuel respiration and mediate cellular energy transduction. Mitochondrial NAD(+) transporters have been identified in yeast and plants(1,2), but thei ...

NATURE RESEARCH2020

A ligand-based system for receptor-specific delivery of proteins

Kai Johnsson, Luc Reymond

Gene delivery using vector or viral-based methods is often limited by technical and safety barriers. A promising alternative that circumvents these shortcomings is the direct delivery of proteins into cells. Here we introduce a non-viral, ligand-mediated p ...

Springer Nature2019

Small-Molecule Fluorescent Probes for Live-Cell Super-Resolution Microscopy

Kai Johnsson, Aleksandar Salim, Michelle Susanne Frei, Lu Wang

Super-resolution fluorescence microscopy is a powerful tool to visualize biomolecules and cellular structures at the nanometer scale. Employing these techniques in living cells has opened up the possibility to study dynamic processes with unprecedented spa ...

AMER CHEMICAL SOC2019

A biosensor for measuring NAD(+) levels at the point of care

Kai Johnsson, Luc Patiny, Elena Katsyuba, Johan Auwerx, Qiuliyang Yu, Lin Xue

The cellular level of nicotinamide adenine dinucleotide (NAD(+)), through its different functions, affects cellular metabolism and signalling(1-3). A decrease in the NAD(+) content has been associated with various pathologies and physiological aging(4,5), ...

NATURE PUBLISHING GROUP2019

Photoactivation of silicon rhodamines via a light-induced protonation

Kai Johnsson, Luc Reymond, Michelle Susanne Frei

Photoactivatable fluorophores are important for single-particle tracking and super-resolution microscopy. Here we present a photoactivatable fluorophore that forms a bright silicon rhodamine derivative through a light-dependent protonation. In contrast to ...

Nature Research2019

Semisynthetic biosensors for mapping cellular concentrations of nicotinamide adenine dinucleotides

Kai Johnsson, Luc Reymond, Olivier Vincent Sallin

2018

A New Fluorogenic Small-Molecule Labeling Tool for Surface Diffusion Analysis and Advanced Fluorescence Imaging of beta-site Amyloid Precursor Protein-Cleaving Enzyme 1 Based on Silicone Rhodamine: SiR-BACE1

Kai Johnsson, Johannes Broichhagen

2018

Control of mechanical pain hypersensitivity in mice through ligand-targeted photoablation of TrkB-positive sensory neurons

Kai Johnsson, Luc Reymond, Sebastian Lechner

Nature Research2018

A Chemogenetic Approach for the Optical Monitoring of Voltage in Neurons

Rudolf Hovius, Kai Johnsson, Luc Reymond, Howard Riezman, Efthymia Prifti

Wiley-VCH Verlag GmbH2018

The metabolite BH4 controls T cell proliferation in autoimmunity and cancer

Kai Johnsson, Jairo Alexander Lozano Moreno, Yann Mathieu Pierson

Genetic regulators and environmental stimuli modulate T cell activation in autoimmunity and cancer. The enzyme co-factor tetrahydrobiopterin (BH4) is involved in the production of monoamine neurotransmitters, the generation of nitric oxide, and pain(1,2). ...

NATURE PUBLISHING GROUP2018

Semisynthetic sensor proteins enable metabolic assays at the point of care

Kai Johnsson, Rudolf Griss, Qiuliyang Yu, Lin Xue, Julien Hiblot

Monitoring metabolites at the point of care could improve the diagnosis and management of numerous diseases. Yet for most metabolites, such assays are not available. We introduce semisynthetic, light-emitting sensor proteins for use in paper-based metaboli ...

American Association for the Advancement of Science2018

Sensors, methods and kits for detecting nadph based on resonance energy transfer

Kai Johnsson, Qiuliyang Yu

The invention relates to the detection of the cofactor reduced nicotinamide adenine dinucleotide phosphate (NADPH). Provided is a sensor molecule for the resonance energy transfer (RET)-based detection of NADPH, the sensor comprising a segment A connected ...

2018

SNAP-Tagged Nanobodies Enable Reversible Optical Control of a G Protein-Coupled Receptor via a Remotely Tethered Photoswitchable Ligand

Kai Johnsson, Helen Rebecca Ostlund Farrants, Johannes Broichhagen

G protein-coupled receptors (GPCRs) mediate the transduction of extracellular signals into complex intracellular responses. Despite their ubiquitous roles in physiological processes and as drug targets for a wide range of disorders, the precise mechanisms ...

AMER CHEMICAL SOC2018

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