Shedding Light on Luminescence - Scientists at HZB reveal the structure of a designer protein
Band model of the fluorescent protein “Dreiklang”,
the structure of which was measured at the electron
storage ring BESSY.
Fluorescent proteins are important investigative tools in the biosciences: Coupled to other proteins, they help us to study the processes of life inside cells and organisms at the molecular level. Fluorescent proteins are made to light up at specific target sites or to become dark again where necessary. In other words, they are switched on and off like light bulbs. Now, for the first time, at Helmholtz-Zentrum Berlin (HZB) scientists have studied the structural characteristics involved in fluorescence on one single protein crystal when switched on and when switched off. Their results are published in Nature Biotechnology (doi:10.1038/nbt.1952).
The researchers from the Max Planck Institute for Biophysical Chemistry in Göttingen and from Freie Universität Berlin performed their work on the MX Beamline BL14.2 at HZB’s electron storage ring BESSY, which is co-operated together with FU-Berlin, HU, MDC and FMP as part of the Joint Berlin MX Laboratory. The intense X-ray light on the beamline can be used to measure protein crystals at extremely high resolution. The object of study was a green-fluorescent protein dubbed “Dreiklang”. They first switched the protein crystal from fluorescent to non-fluorescent state at room temperature – they “switched it off”. Next, the scientists measured the deep-frozen crystal at around minus 170 degrees Celsius on the BESSY beamline.
“Normally a protein crystal breaks when heated back up to room temperature after measurement,” Dr. Uwe Müller, head of the HZB “Macromolecular Crystallography” workgroup, describes the special nature of the study: “In this case, however, it was possible to keep the protein functional.” The researchers brought the protein crystal back into fluorescent state at 30 degrees Celsius, then froze it and studied it a second time on the beamline. The subsequent data analysis revealed that the protein’s structure differs when switched on or switched off by the number of water molecules embedded in it.
“The study of the Dreiklang molecule broke new ground at BESSY,” Uwe Müller says. It is a designer protein that does not naturally exist in this form. Müller continues: “The MX beamline lets scientists study not only natural proteins but even entirely novel materials. The work with Dreiklang has taken us another step forward in HZB’s core research area of ‘Functional Materials’,” Müller concludes.
- BESSY II: How intrinsic oxygen shortens the lifespan of solid-state batteriesAlthough solid-state batteries (SSBs) demonstrate high performance and are intrinsically safe, their capacity currently declines rapidly. A team from the TU Wien, Humboldt-University Berlin and HZB has now analysed a TiS₂|Li₃YCl₆ solid-state half-cell in operando at BESSY II using a special sample environment that allows for non-destructive investigation under real operating conditions. Data obtained by combination of soft and hard X-ray photoelectron spectroscopy (XPS and HAXPES) revealed a new degradation mechanism that had not previously been identified in solid-state batteries. They have gained some surprising insights, particularly regarding the harmful role played by intrinsic oxygen. This study provides valuable information for improving design and handling of such batteries.
- Spintronics at BESSY II: Real-time analysis of magnetic bilayer systemsSpintronic devices enable data processing with significantly lower energy consumption. They are based on the interaction between ferromagnetic and antiferromagnetic layers. Now, a team from Freie Universität Berlin, HZB and Uppsala University has succeeded in tracking, for each layer separately, how the magnetic order changes after a short laser pulse has excited the system. They were also able to identify the main cause of the loss of antiferromagnetic order in the oxide layer: the excitation is transported from the hot electrons in the ferromagnetic metal to the spins in the antiferromagnet.
- Environmental Chemistry at BESSY II: Radicals in waterwaysHow do radicals form in aqueous solutions when exposed to UV light? This question is important for health research and environmental protection, for example with regard to the overfertilisation of water bodies by intensive agriculture. A team at BESSY II has now developed a new method of investigating hydroxyl radicals in solution. By using a clever trick, the scientists gained surprising insights into the reaction pathway.