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The class 2 type V CRISPR effector Cas12 is thought to have evolved from the IS200/IS605 superfamily of transposon-associated TnpB proteins 1 . Recent studies have identified TnpB proteins as miniature RNA-guided DNA endonucleases 2 , 3 . TnpB associates with a single, long RNA (ωRNA) and cleaves double-stranded DNA targets complementary to the ωRNA guide. However, the RNA-guided DNA cleavage mechanism of TnpB and its evolutionary relationship with Cas12 enzymes remain unknown. Here we report the cryo-electron microscopy (cryo-EM) structure of Deinococcus radiodurans ISDra2 TnpB in complex with its cognate ωRNA and target DNA. In the structure, the ωRNA adopts an unexpected architecture and forms a pseudoknot, which is conserved among all guide RNAs of Cas12 enzymes. Furthermore, the structure, along with our functional analysis, reveals how the compact TnpB recognizes the ωRNA and cleaves target DNA complementary to the guide. A structural comparison of TnpB with Cas12 enzymes suggests that CRISPR–Cas12 effectors acquired an ability to recognize the protospacer-adjacent motif-distal end of the guide RNA–target DNA heteroduplex, by either asymmetric dimer formation or diverse REC2 insertions, enabling engagement in CRISPR–Cas adaptive immunity. Collectively, our findings provide mechanistic insights into TnpB function and advance our understanding of the evolution from transposon-encoded TnpB proteins to CRISPR–Cas12 effectors. Cryo-electron microscopy analysis of the Deinococcus radiodurans ISDra2 TnpB in complex with its cognate ωRNA and target DNA provides insights into the mechanism of TnpB function and the evolution of CRISPR–Cas12 effectors.

Lysophosphatidic acid receptor 1 (LPA 1 ) is one of the six G protein-coupled receptors activated by the bioactive lipid, lysophosphatidic acid (LPA). LPA 1 is a drug target for various diseases, including cancer, inflammation, and neuropathic pain. Notably, LPA 1 agonists have potential therapeutic value for obesity and urinary incontinence. Here, we report a cryo-electron microscopy structure of the active human LPA 1 -G i complex bound to ONO-0740556, an LPA analog with more potent activity against LPA 1 . Our structure elucidated the details of the agonist binding mode and receptor activation mechanism mediated by rearrangements of transmembrane segment 7 and the central hydrophobic core. A structural comparison of LPA 1 and other phylogenetically-related lipid-sensing GPCRs identified the structural determinants for lipid preference of LPA 1 . Moreover, we characterized the structural polymorphisms at the receptor-G-protein interface, which potentially reflect the G-protein dissociation process. Our study provides insights into the detailed mechanism of LPA 1 binding to agonists and paves the way toward the design of drug-like agonists targeting LPA 1 . LPA 1 is one of the GPCRs that are drug targets for various diseases. Here the authors report a cryo-EM structure of the active human LPA 1 -G i complex bound to an LPA analog with more potent activity against LPA 1 and clarified the ligand recognition mechanism.

Energy transfer from light-harvesting ketocarotenoids to the light-driven proton pump xanthorhodopsins has been previously demonstrated in two unique cases: an extreme halophilic bacterium 1 and a terrestrial cyanobacterium 2 . Attempts to find carotenoids that bind and transfer energy to abundant rhodopsin proton pumps 3 from marine photoheterotrophs have thus far failed 4 – 6 . Here we detected light energy transfer from the widespread hydroxylated carotenoids zeaxanthin and lutein to the retinal moiety of xanthorhodopsins and proteorhodopsins using functional metagenomics combined with chromophore extraction from the environment. The light-harvesting carotenoids transfer up to 42% of the harvested energy in the violet- or blue-light range to the green-light absorbing retinal chromophore. Our data suggest that these antennas may have a substantial effect on rhodopsin phototrophy in the world’s lakes, seas and oceans. However, the functional implications of our findings are yet to be discovered. Light energy transfer from abundant hydroxylated carotenoids to the retinal moiety of widespread light-driven proton pumps is detected.

Channelrhodopsins (ChRs) are light-gated ion channels and invaluable tools for optogenetic applications. Recent developments in multicolor optogenetics, in which different neurons are controlled by multiple colors of light simultaneously, have increased the demand for ChR mutants with more distant absorption wavelengths. Here we report the 2.7 Å-resolution cryo-electron microscopy structure of a ChR from Klebsormidium nitens (KnChR), which is one of the most blue-shifted ChRs. The structure elucidates the 6- s-cis configuration of the retinal chromophore, indicating its contribution to a distinctive blue shift in action spectra. The unique architecture of the C-terminal region reveals its role in the allosteric modulation of channel kinetics, enhancing our understanding of its functional dynamics. Employing a rational approach, we developed mutants with blue-shifted action spectra. Finally, we confirm that UV or deep-blue light can activate KnChR-transfected precultured neurons, expanding its utility in optogenetic applications. Our findings contribute valuable insights to advance optogenetic tools and enable refined capabilities in neuroscience experiments. Channelrhodopsins are light-gated ion channels for optogenetics. Here, authors report the 2.7 Å cryo-EM structure of a blue-shifted channelrhodopsin from Klebsormidium nitens, revealing a 6-s-cis retinal configuration and unique C-terminal modulation.

Dizziness is a common complaint in emergency medicine. Algorithms such as the standing assessment (STANDING) and head impulse, nystagmus, and distortion tests (Head Impulse, Nystagmus, and Test of Skew (HINTS)) are used as \"diagnostic aids\" and \"initial assessment tools\". However, obstructive sleep apnea (OSA) is often excluded from these paradigms, despite evidence showing an association between OSA and dizziness. We report two patients with unexplained dizziness in whom conventional evaluations were non-diagnostic. Both exhibited sleep-related symptoms, and simplified polysomnography revealed moderate OSA. Mandibular advancement devices led to symptom resolution. OSA may underlie dizziness when standard assessments are inconclusive. Screening for sleep-related symptoms is essential. We suggest targeted OSA screening in patients with unexplained dizziness and relevant risk factors.

Lasso peptides exhibit a unique lariat-like knotted structure imparting exceptional stability and thus show promise as therapeutic agents that target cell-surface receptors. One such receptor is the human endothelin type B receptor (ET B ), which is implicated in challenging cancers with poor immunotherapy responsiveness. The Streptomyces -derived lasso peptide, RES-701-3, is a selective inhibitor for ET B and a compelling candidate for therapeutic development. However, meager production from a genetically recalcitrant host has limited further structure-activity relationship studies of this potent inhibitor. Here, we report cryo-electron microscopy structures of ET B receptor in both its apo form and complex with RES-701-3, facilitated by a calcineurin-fusion strategy. Hydrophobic interactions between RES-701-3 and the transmembrane region of the receptor, especially involving two tryptophan residues, play a crucial role in RES-701-3 binding. Furthermore, RES-701-3 prevents conformational changes associated with G-protein coupling, explaining its inverse agonist activity. A comparative analysis with other lasso peptides and their target proteins highlights the potential of lasso peptides as precise drug candidates for G-protein-coupled receptors. This structural insight into RES-701-3 binding to ET B receptor offers valuable information for the development of novel therapeutics targeting this receptor and provides a broader understanding of lasso peptide interactions with human cell-surface receptors. Cryo-EM structures reveal how the lasso peptide binds the ET B receptor, blocking its activation via key hydrophobic interactions. These findings advance lasso peptides as potential drugs for hard-to-treat cancers and GPCR-targeting therapies.

Background/Objectives: Malnutrition, muscle wasting, and fluid overload are highly prevalent in patients undergoing maintenance hemodialysis (HD) and may contribute to increased mortality risk. However, the combined impact of these factors has not been fully elucidated. Methods: In this multicenter prospective cohort study, we enrolled 368 patients in maintenance HD at four dialysis facilities in Japan. Malnutrition was defined as moderate or higher nutritional risk using the nutritional risk index for Japanese hemodialysis patients (NRI-JH). Low muscle mass was assessed using the skeletal muscle mass index (SMI) according to the Asian Working Group for Sarcopenia 2019 (AWGS 2019), and elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) was defined as values in the top quartile (≥7650 pg/mL). Mortality risk was analyzed using Cox proportional hazards models. Associations with inflammation, assessed by C-reactive protein (CRP), were also explored. Results: Over a three-year follow-up period, 52 deaths occurred. Malnutrition, low muscle mass, and elevated NT-proBNP were each independently associated with increased all-cause mortality (HR: 4.98, 3.25, and 5.45, respectively). Patients with multiple concurrent risk factors had significantly worse survival. Although CRP was positively associated with these risk factors, it was not an independent predictor of mortality. Conclusions: Malnutrition, low muscle mass, and elevated NT-proBNP are independent and additive risk factors for mortality in HD patients. These findings highlight the need for integrated assessment and management strategies to improve prognoses in this high-risk population.

Background/Objectives: The phase angle (PA), derived from bioelectrical impedance analysis (BIA), reflects cellular integrity and nutritional status. Previous studies have reported associations between PA, QOL, and prognosis in hemodialysis patients; however, evidence in Japanese populations remains limited. This multicenter study aimed to confirm and extend these associations by examining the relationships of PA with QOL domains and survival outcomes in maintenance HD patients. Methods: In this multicenter cross-sectional study, 319 HD patients were stratified into sex-specific PA quartiles, and baseline characteristics, laboratory data, and body composition measures were compared across groups. Health-related QOL was assessed using the SF-36 and KDQOL-SF™. Associations between PA and QOL were tested with multivariable linear regression models. Survival was evaluated using Kaplan–Meier analysis with Bonferroni-adjusted pairwise comparisons. Results: Higher PA was significantly associated with favorable nutritional and laboratory parameters, including higher hemoglobin, albumin, creatinine, and GNRI, and lower NT-proBNP. PA also correlated positively with muscle mass and intracellular water, and inversely with the ECW/ICW ratio. Multivariable analyses showed that PA remained independently associated with several physical QOL domains, including physical functioning, role—physical, and general health, even after adjustment for dialysis adequacy (Kt/V) and inflammation (CRP). Kaplan–Meier analysis demonstrated lower survival in the lowest PA quartile, and ROC analysis identified sex-specific cutoff values for predicting mortality (4.0° for females, 4.8° for males). Conclusions: This multicenter confirmatory study showed that PA is independently associated with nutritional status, physical QOL, and mortality in maintenance hemodialysis patients. PA may serve as a practical, noninvasive biomarker for nutritional and functional assessment in clinical practice.

GPR34 is a recently identified G-protein coupled receptor, which has an immunomodulatory role and recognizes lysophosphatidylserine (LysoPS) as a putative ligand. Here, we report cryo-electron microscopy structures of human GPR34-G i complex bound with one of two ligands bound: either the LysoPS analogue S3E-LysoPS, or M1, a derivative of S3E-LysoPS in which oleic acid is substituted with a metabolically stable aromatic fatty acid surrogate. The ligand-binding pocket is laterally open toward the membrane, allowing lateral entry of lipidic agonists into the cavity. The amine and carboxylate groups of the serine moiety are recognized by the charged residue cluster. The acyl chain of S3E-LysoPS is bent and fits into the L-shaped hydrophobic pocket in TM4-5 gap, and the aromatic fatty acid surrogate of M1 fits more appropriately. Molecular dynamics simulations further account for the LysoPS-regioselectivity of GPR34. Thus, using a series of structural and physiological experiments, we provide evidence that chemically unstable 2-acyl LysoPS is the physiological ligand for GPR34. Overall, we anticipate the present structures will pave the way for development of novel anticancer drugs that specifically target GPR34. GPR34 is a GPCR which has an immunomodulatory role and recognizes lysophosphatidylserine (LysoPS) as a putative endogenous ligand. Here, authors report two cryo-EM structures of human GPR34-Gi complex with one of two ligands bound: either the LysoPS analogue S3E-LysoPS, or its derivative M1.

Sleep disturbances are highly prevalent in hemodialysis (HD) patients and are associated with impaired quality of life (QOL) and poor outcomes. However, the independent impact of sleep quality on QOL and mortality in this population remains unclear. In this multicenter observational study, 346 HD patients completed the Kidney Disease Quality of Life-Short Form (KDQOL-SF). A composite sleep score was derived from sleep-related items, and patients were stratified into tertiles (Q1-Q3). Clinical characteristics, QOL outcomes, and survival were compared across tertiles. Associations between sleep quality and QOL domains were assessed using linear regression, while Cox proportional hazards models were applied to evaluate mortality risk. Patients in the lowest tertile (Q1) consistently demonstrated significantly lower scores across multiple SF-36 and kidney-disease-specific QOL domains compared with Q2 and Q3 (all < 0.001). Kaplan-Meier analysis showed lower cumulative survival in Q1 (log-rank = 0.012). In Cox models, Q1 was associated with higher mortality compared to Q3 in both unadjusted (HR, 2.58; 95% CI, 1.46-4.54; = 0.001) and adjusted models (Model 3: HR, 2.04; 95% CI, 1.11-3.77; = 0.023). The associations between Q1 and Q2 were attenuated after full adjustment (HR, 1.88; 95% CI, 0.98-3.60; = 0.058). Poor sleep quality was independently associated with impaired QOL and increased all-cause mortality in HD patients. These associations remained significant even after adjustment for inflammation and dialysis adequacy, suggesting that sleep quality reflects a distinct pathophysiological condition and may serve as an important, potentially modifiable indicator of patient well-being and prognosis.