Mechanism-guided engineering of a minimal biological particle for genome editing.

The widespread application of genome editing to treat and cure disease requires the delivery of genome editors into the nucleus of target cells. Enveloped delivery vehicles (EDVs) are engineered virally derived particles capable of packaging and delivering CRISPR-Cas9 ribonucleoproteins (RNPs). However, the presence of lentiviral genome encapsulation and replication proteins in EDVs has obscured the underlying delivery mechanism and precluded particle optimization.

Structural basis for the inhibition of PRC2 by active transcription histone posttranslational modifications.

Polycomb repressive complex 2 (PRC2) trimethylates histone H3 on K27 (H3K27me3) leading to gene silencing that is essential for embryonic development and maintenance of cell identity. PRC2 is regulated by protein cofactors and their crosstalk with histone modifications. Trimethylated histone H3 on K4 (H3K4me3) and K36 (H3K36me3) localize to sites of active transcription and inhibit PRC2 activity through unknown mechanisms.

Fe starvation induces a second LHCI tetramer to photosystem I in green algae.

Iron (Fe) availability limits photosynthesis at a global scale where Fe-rich photosystem (PS) I abundance is drastically reduced in Fe-poor environments. We used single-particle cryo-electron microscopy to reveal a unique Fe starvation-dependent arrangement of light-harvesting chlorophyll (LHC) proteins where Fe starvation-induced TIDI1 is found in an additional tetramer of LHC proteins associated with PSI in and . These cosmopolitan green algae are resilient to poor Fe nutrition.

Structures of vertebrate R2 retrotransposon complexes during target-primed reverse transcription and after second strand nicking.

R2 retrotransposons are model site-specific eukaryotic non-LTR retrotransposons that copy-and-paste into gene loci encoding ribosomal RNAs. Recently we demonstrated that avian A-clade R2 proteins achieve efficient and precise insertion of transgenes into their native safe-harbor loci in human cells. The features of A-clade R2 proteins that support gene insertion are not characterized.

Debris Embolization to the Lung After a Bioprosthetic (Mitroflow®) Valve Fracture.

This case report shows a valve in valve procedure in pulmonary position of a 19-year-old male with a repaired Tetralogy of Fallot. After initial correction, a Mitroflow 23 mm bioprosthetic valve was implanted in pulmonary position. Nine years later severe degeneration of the valve occurred.