Structure of the Head of the Bartonella Adhesin BadA

Trimeric autotransporter adhesins (TAAs) are a major class of proteins by which pathogenic proteobacteria adhere to their hosts. Prominent examples include Yersinia YadA, Haemophilus Hia and Hsf, Moraxella UspA1 and A2, and Neisseria NadA. TAAs also occur in symbiotic and environmental species and presumably represent a general solution to the problem of adhesion in proteobacteria. The general structure of TAAs follows a head-stalk-anchor architecture, where the heads are the primary mediators of attachment and autoagglutination. In the major adhesin of Bartonella henselae, BadA, the head consists of three domains, the N-terminal of which shows strong sequence similarity to the head of Yersinia YadA. The two other domains were not recognizably similar to any protein of known structure. We therefore determined their crystal structure to a resolution of 1.1 Å. Both domains are β-prisms, the N-terminal one formed by interleaved, five-stranded β-meanders parallel to the trimer axis and the C-terminal one by five-stranded β-meanders orthogonal to the axis. Despite the absence of statistically significant sequence similarity, the two domains are structurally similar to domains from Haemophilus Hia, albeit in permuted order. Thus, the BadA head appears to be a chimera of domains seen in two other TAAs, YadA and Hia, highlighting the combinatorial evolutionary strategy taken by pathogens

Arming Th17 cells for antifungal host defense

Interleukin 17 (IL-17)-mediated immunity has emerged as a crucial host defense mechanism against fungal infections. The family of IL-17 cytokines is phylogenetically ancient, but remains the least understood of all cytokine subclasses. The effects mediated by IL-17 are pleiotropic and include the induction of antimicrobial peptides as well as cytokines and chemokines that lead to the recruitment and activation of neutrophils. Neutrophils in turn are key effector cells of the antifungal defense. CD4+ T cells act as a major source of IL-17 and a lot has been learned about these cells since their discovery a decade ago. This review highlights key aspects of the underlying mechanisms regulating the development of Th17 responses during fungal infections. We discuss the impact of different subsets of antigen-presenting cells, innate cytokine signals and tissue-specific factors on Th17 differentiation, and we highlight the prerequisites for the mediation by Th17 cells of vaccine immunity against fungi

A FRET-Based Assay for the Identification and Characterization of Cereblon Ligands

Cereblon serves as an ubiquitin ligase substrate receptor that can be tuned toward different target proteins by various cereblon-binding agents. This offers one of the most promising avenues for targeted protein degradation in cancer therapy, but cereblon binding can also mediate teratogenic effects. We present an effective assay that is suited for high-throughput screening of compound libraries for off-target cereblon interactions but also can guide lead optimization and rational design of novel cereblon effector molecules

A 4.7-THz gas laser local oscillator for GREAT on SOFIA

A particularly important transition for astronomy is the OI fine structure line at 4.7 THz. It is an important cooling line of the interstellar medium and allows studying the chemical composition, the evolution, and the dynamical behavior of astronomical objects. Consequently, this transition is a main target to be observed with GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be operated on board of SOFIA. A major challenge for a heterodyne receiver operating at such a high frequency is the local oscillator (LO). Despite significant progress in the development of a quantum-cascade laser based LO [1] the baseline design for GREAT is an optically pumped gas laser operated at 4.7 THz. In this report we will present the design and performance of the 4.7-THz gas laser LO for SOFIA. The LO is based on a radio frequency excited CO2 laser which has a sealed-off gas volume and which is frequency tunable by a grating. The CO2 laser is operated on the 9P12 transition of the CO2 molecule. The output emission is focused into the THz laser resonator. The THz laser is transversely excited. It operates on the 4.75 THz line of 13CH3OH. For frequency stabilization of the CO2 laser a small part of its output radiation is guided into a Fabry-Pérot interferometer (FPI) which serves as a length or frequency reference. In order to compensate for temperature or pressure induced drifts of the FPI length the emission of a frequency stabilized a helium-neon (HeNe) laser is coupled into the FPI as well. The FPI is locked to the emission of the HeNe laser. We will present the design and the performance of the LO with respect to output power, short and long term power stability, and beam profile. The system is ready and awaits implementation in GREAT and operation on board of SOFIA

Systematic review and meta-analysis of PIT tagging effects on mortality and growth of juvenile salmonids

A systematic review and meta-analysis was conducted to evaluate the appropriate tag:fish size ratio when tagging juvenile salmonids (genera Oncorhynchus, Salmo, and Salvelinus). The review yielded 18 publications with 211 control and treatment groups reporting results from laboratory studies on the effects of passive integrated transponder (PIT) tags, plus a small number of additional studies on acoustic transmitters. A meta-analysis of the PIT tagging studies showed significant heterogeneity among studies with respect to mortality. Meta-regression revealed that juvenile salmonid mortality increased curvilinearly with the tag:fish length ratio, indicating that mortality risk is rapidly enhanced as smaller fish or larger tag sizes are used. The tag:fish length ratio effect on daily length or mass gain increased linearly. The results provide an estimate of the effects of the tag:fish length ratio on mortality and growth parameters in juvenile salmonids. Based on this, we suggest that researchers can follow best practices for tagging juvenile salmonids with tags that are not greater than 17.5% of fish total length (TL). This equates a minimum size threshold of 131 mm TL for tagging salmonids with 23-mm PIT tags, and 69 mm TL with 12-mm PIT tags. This information can assist researchers, managers, and welfare agencies striving to use the best possible evidence to make informed decisions regarding fish tagging. Acoustic Tag effects Passive integrated transponder Salmon Trout MortalitypublishedVersio

Your personalized protein structure: Andrei N. Lupas fused to GCN4 adaptors

AbstractThis work presents a protein structure that has been designed purely for aesthetic reasons, symbolizing decades of coiled-coil research and praising its most fundamental model system, the GCN4 leucine zipper. The GCN4 leucine zipper is a highly stable coiled coil which can be tuned to adopt different oligomeric states via mutation of its core residues. For these reasons it is used in structural studies as a stabilizing fusion adaptor. On the occasion of the 50th birthday of Andrei N. Lupas, we used it to create the first personalized protein structure: we fused the sequence ANDREI-N-LVPAS in heptad register to trimeric GCN4 adaptors and determined its structure by X-ray crystallography. The structure demonstrates the robustness and versatility of GCN4 as a fusion adaptor. We learn how proline can be accommodated in trimeric coiled coils, and put the structure into the context of the other GCN4-fusion structures known to date

Performance of the 4.7-THz Local Oscillator with Quantum Cascade Laser on Board of SOFIA

— The design and the performance of a 4.7-THz local oscillator (LO) for the GREAT (German REceiver for Astronomy at Terahertz frequencies) heterodyne spectrometer on SOFIA, the Stratospheric Observatory for Infrared Astronomy, are presented. The LO is based on a quantum-cascade laser, which is mounted in a compact mechanical cryocooler. It delivers up to 150 µW output power into a nearly Gaussian shaped beam around the frequency of the fine structure line of neutral atomic oxygen, OI, at 4.7448 THz