In addition, by leveraging in silico structure-guided design of the tail fiber, we show PVCs can be reprogrammed to target organisms not initially targeted—including human cells and mice—with targeting efficiencies approaching 100%. Lastly, we present compelling evidence that PVCs can load and deliver a broad spectrum of proteins, including Cas9, base editors, and toxins, into human cells, effectively illustrating their functional potential. Our research shows that PVCs function as programmable protein delivery platforms, suggesting potential applications in gene therapy, cancer treatment, and biological control applications.

The development of therapies for pancreatic ductal adenocarcinoma (PDA), a highly lethal malignancy with an increasing incidence and poor prognosis, is crucial. Intensive study of tumor metabolism, although pursued for over a decade, has been constrained by the multifaceted metabolic adaptability of tumors and the significant possibility of toxicity in this anti-cancer strategy. find more In order to reveal PDA's specific dependence on de novo ornithine synthesis from glutamine, our genetic and pharmacological research encompasses human and mouse in vitro and in vivo models. The ornithine aminotransferase (OAT) pathway, facilitating polyamine synthesis, is indispensable for the progression of tumor growth. OAT activity, exhibiting a directional pattern, is generally prevalent during infancy, a notable divergence from the reliance of adult normal tissues and most other cancer types on arginine-derived ornithine for polyamine biosynthesis. Arginine depletion within the PDA tumor microenvironment is linked to this dependency, which is fueled by mutant KRAS. KRAS activation prompts the expression of OAT and polyamine synthesis enzymes, which consequently alters the transcriptome and the open chromatin architecture in PDA tumor cells. The exclusive dependence of pancreatic cancer cells on OAT-mediated de novo ornithine synthesis, in contrast to normal tissues, offers a therapeutic advantage with minimal side effects for patients.

By cleaving GSDMB, a pore-forming protein of the gasdermin family, granzyme A, a cytotoxic molecule produced by lymphocytes, initiates the process of target cell pyroptosis. Studies on the effect of the Shigella flexneri ubiquitin-ligase virulence factor IpaH78 on the degradation of GSDMB and the gasdermin family member GSDMD45 have yielded disparate results. The JSON schema for sentence 67: a list of sentences. The precise targeting mechanism of IpaH78 for both gasdermins is currently unknown, and the role of GSDMB in pyroptosis is now the subject of questioning. We unveil the crystal structure of the IpaH78-GSDMB complex, illustrating IpaH78's binding to the GSDMB pore-forming domain. We confirm IpaH78's specific interaction with human GSDMD, in contrast to mouse GSDMD, through a similar molecular mechanism. The autoinhibition characteristic of the full-length GSDMB structure is markedly stronger than seen in other gasdermin structures. GSDMB's diverse splicing isoforms are all substrates for IpaH78, but their pyroptotic capabilities vary. GSDMB isoforms possessing exon 6 exhibit pore-forming activity and pyroptosis, while those lacking it do not. Employing cryo-electron microscopy, we ascertain the structure of the 27-fold-symmetric GSDMB pore and exhibit the conformational alterations that trigger pore development. Exon-6-derived components play a pivotal part in pore formation, as revealed by the structure, thereby elucidating the underlying cause of pyroptosis impairment in the non-canonical splicing variant, as observed in recent studies. The isoform makeup of cancer cell lines varies considerably, correlating with the development and degree of pyroptosis following stimulation with GZMA. This study demonstrates how pathogenic bacteria and mRNA splicing finely regulate GSDMB's pore-forming activity, revealing the fundamental structural mechanisms.

Ice, present everywhere on Earth, significantly impacts various domains, including the intricate workings of cloud physics, the complex phenomenon of climate change, and the vital process of cryopreservation. Ice's role is influenced by the pattern of its formation and the resultant structural configuration. Even so, these matters are not completely comprehended. A noteworthy, longstanding discussion continues regarding whether water can freeze to form cubic ice, a currently unexplored phase within the phase diagram of common hexagonal ice. find more A consensus view, formed by aggregating laboratory data, suggests that this variation is attributed to the inability to recognize cubic ice from stacking-disordered ice, a mix of cubic and hexagonal structures as cited in references 7 through 11. Cryogenic transmission electron microscopy, incorporating low-dose imaging, indicates the preferential nucleation of cubic ice at low-temperature interfaces. This produces two distinct crystal types, cubic and hexagonal ice, resulting from water vapor deposition at 102 Kelvin. We additionally pinpoint a succession of cubic-ice defects, encompassing two categories of stacking disorder, revealing the structural evolution dynamics supported by molecular dynamics simulations. Transmission electron microscopy allows for the direct real-space imaging of ice formation and its dynamic behavior at the molecular level, offering opportunities in ice research at the molecular scale and potentially applicable to other hydrogen-bonding crystals.

The placenta, an extraembryonic organ manufactured by the fetus, and the decidua, the uterine mucosal layer, must interact effectively to properly support and protect the developing fetus during its pregnancy. find more Extravillous trophoblast cells (EVTs) originating from placental villi actively invade the decidua, consequently remodeling maternal arteries into high-conductance vessels. The foundation for common pregnancy disorders, such as pre-eclampsia, is laid by irregularities in trophoblast invasion and arterial conversion during early pregnancy. A spatially resolved, multiomic single-cell atlas of the entire human maternal-fetal interface, encompassing the myometrium, has been generated, allowing for a comprehensive analysis of trophoblast differentiation trajectories. From this cellular map, we were able to infer the probable transcription factors that are involved in EVT invasion. These transcription factors were subsequently shown to be preserved in in vitro models of EVT differentiation from primary trophoblast organoids and trophoblast stem cells. Our analysis focuses on the transcriptomes of the final cell states within trophoblast-invaded placental bed giant cells (fused multinucleated EVTs) and endovascular EVTs (which form blockages inside maternal arteries). We anticipate the cell-cell communication events that promote trophoblast invasion and placental bed giant cell formation, and we propose a model illustrating the dual roles of interstitial and endovascular extravillous trophoblasts in driving arterial modifications during early pregnancy. A comprehensive analysis of postimplantation trophoblast differentiation, as revealed by our data, allows for the design of experimental models that reflect the human placenta's development in early pregnancy.

Pore-forming proteins, Gasdermins (GSDMs), have critical functions in host defense, including the induction of pyroptosis. GSDMB distinguishes itself among GSDMs through a distinctive lipid-binding signature and the absence of a general agreement on its pyroptotic potential. GSDMB's capacity for directly killing bacteria, a recently observed phenomenon, is mediated by its pore-forming action. IpaH78, a virulence factor secreted by Shigella, an intracellular human-adapted enteropathogen, subverts the host defense mechanism of GSDMB by initiating ubiquitination-dependent proteasomal degradation of GSDMB4. The complex of human GSDMB with Shigella IpaH78 and the GSDMB pore is characterized via cryogenic electron microscopy. The structural arrangement of the GSDMB-IpaH78 complex establishes a three-residue motif comprising negatively charged residues within the GSDMB protein as the structural determinant, which is identified by IpaH78. Only human GSDMD, and not mouse GSDMD, exhibits this conserved motif, leading to the species-specificity of the IpaH78 effect. GSDMB's pore formation is regulated by an alternative splicing-regulated interdomain linker, observable within its structural pore. While GSDMB isoforms featuring a standard interdomain linker preserve normal pyroptotic activity, other isoforms display reduced or non-existent pyroptotic function. This research illuminates the molecular underpinnings of Shigella IpaH78's recognition and targeting of GSDMs, highlighting a structural determinant in GSDMB crucial for its pyroptotic function.

Non-enveloped viruses, in order to release their progeny, require cell lysis, thus highlighting the potential for these viruses to induce cellular demise. Noroviruses, a type of virus, yet there's no established pathway to explain cell death and disintegration that results from a norovirus infection. Through investigation, we pinpoint the molecular mechanism behind norovirus-induced cellular demise. Through our study, we found that the norovirus NTPase NS3 includes an N-terminal four-helix bundle domain that is homologous to the membrane-disrupting domain of the pseudokinase mixed lineage kinase domain-like protein (MLKL). The mitochondrial localization signal of NS3 is instrumental in its targeting to mitochondria, which, in turn, induces cell death. Binding of full-length NS3 and an N-terminal protein fragment to mitochondrial membrane cardiolipin led to membrane permeabilization and mitochondrial dysfunction. The mitochondrial localization motif and N-terminal region of NS3 were crucial determinants of cell death, viral dissemination, and viral replication in mice. Viral egress by noroviruses, facilitated by the incorporation of a host MLKL-like pore-forming domain, is suggested to be linked to the induction of mitochondrial dysfunction.

Beyond the limitations of organic and polymeric membranes, freestanding inorganic membranes have the potential to advance separation, catalysis, sensor technology, memory devices, optical filtering, and the field of ionic conductors.