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Christiane Grimm
Humboldt University of Berlin
16Publications
6H-index
119Citations
Publications 16
Newest
#1A. Vogt (Humboldt University of Berlin)H-Index: 43
#2Arita Silapetere (Humboldt University of Berlin)H-Index: 2
Last.Peter Hegemann (Humboldt University of Berlin)H-Index: 60
view all 6 authors...
Abstract Light-driven sodium pumps (NaRs) are microbial rhodopsins that utilize light energy to actively transport sodium ions out of the cell. Here, we used targeted mutagenesis and electrophysiological methods in living cells to demonstrate that NaRs can be converted into light-activated cation channels by molecular engineering. Specifically, introduction of the R109Q mutation into the sodium ion pump of Dokdonia eikasta (KR2) results in passive ion conductance, with a high preference for pota...
#1Christiane Grimm (Humboldt University of Berlin)H-Index: 6
#2Arita Silapetere (Humboldt University of Berlin)H-Index: 2
Last.Peter Hegemann (Humboldt University of Berlin)H-Index: 60
view all 5 authors...
A new microbial rhodopsin class that actively transports sodium out of the cell upon illumination was described in 2013. However, poor membrane targeting of the first-identified sodium pump KR2 in mammalian cells has hindered the direct electrical investigation of its transport mechanism and optogenetic application to date. Accordingly, we designed enhanced KR2 (eKR2), which exhibits improved membrane targeting and higher photocurrents in mammalian cells to facilitate molecular characterization ...
#1Johannes Vierock (Humboldt University of Berlin)H-Index: 5
#2Christiane Grimm (Humboldt University of Berlin)H-Index: 6
Last.Peter Hegemann (Humboldt University of Berlin)H-Index: 60
view all 4 authors...
Channelrhodopsins are light-gated ion channels of green algae used for the precise temporal and spatial control of transmembrane ion fluxes. The channelrhodopsin Chrimson from Chlamydomonas noctigama allows unprecedented deep tissue penetration due to peak absorption at 590 nm. We demonstrate by electrophysiological recordings and imaging techniques that Chrimson is highly proton selective causing intracellular acidification in HEK cells that is responsible for slow photocurrent decline during p...
#1Jonas Wietek (Humboldt University of Berlin)H-Index: 10
Last.J. Simon WiegertH-Index: 12
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Genetic engineering of natural light-gated ion channels has proven a powerful way to generate optogenetic tools for a wide variety of applications. In recent years, blue-light activated engineered anion-conducting channelrhodopsins (eACRs) have been developed, improved, and were successfully applied in vivo. We asked whether the approaches used to create eACRs can be transferred to other well-characterized cation-conducting channelrhodopsins (CCRs) to obtain eACRs with a broad spectrum of biophy...
#1Joel C. D. Kaufmann (Charité)H-Index: 2
#2Benjamin S. KrauseH-Index: 3
Last.Franz Bartl (Charité)H-Index: 28
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Abstract Channelrhodopsins (ChRs) are light-gated ion channels widely used for activating selected cells in large cellular networks. ChR variants with a red-shifted absorption maximum, such as the modified Volvox carteri ChR1 red-activatable channelrhodopsin (“ReaChR,” λmax = 527 nm), are of particular interest because longer wavelengths allow optical excitation of cells in deeper layers of organic tissue. In all ChRs investigated so far, proton transfer reactions and hydrogen bond changes are c...
#1Christiane Grimm (Humboldt University of Berlin)H-Index: 6
#2Johannes Vierock (Humboldt University of Berlin)H-Index: 5
Last.Jonas Wietek (Humboldt University of Berlin)H-Index: 10
view all 4 authors...
Over the past decade, channelrhodopsins became indispensable in neuroscientific research where they are used as tools to non-invasively manipulate electrical processes in target cells. In this context, ion selectivity of a channelrhodopsin is of particular importance. This article describes the investigation of chloride selectivity for a recently identified anion-conducting channelrhodopsin of Proteomonas sulcata via electrophysiological patch-clamp recordings on HEK293 cells. The experimental p...
#1Benjamin S. Krause (Humboldt University of Berlin)H-Index: 3
#2Christiane Grimm (Humboldt University of Berlin)H-Index: 6
Last.Peter Hegemann (Humboldt University of Berlin)H-Index: 60
view all 7 authors...
Abstract Channelrhodopsins (ChRs) are light-activated ion channels widely employed for photostimulation of excitable cells. This study focuses on ReaChR, a chimeric ChR variant with optimal properties for optogenetic applications. We combined electrophysiological recordings with infrared and UV-visible spectroscopic measurements to investigate photocurrents and photochemical properties of ReaChR. Our data imply that ReaChR is green-light activated ( λ max = 532 nm) with a non-rhodopsin-like acti...
#1Christiane Grimm (Humboldt University of Berlin)H-Index: 6
#2A. Vogt (Humboldt University of Berlin)H-Index: 43
Last.Peter Hegemann (Humboldt University of Berlin)H-Index: 60
view all 3 authors...
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