Epigenetic marks uniquely tune the material properties of HP1α condensates.

Biomolecular condensates have emerged as a powerful new paradigm in cell biology with broad implications to human health and disease, particularly in the nucleus where phase separation is thought to underly elements of chromatin organization and regulation. Specifically, it has been recently reported that phase separation of heterochromatin protein 1alpha (HP1α) with DNA contributes to the formation of condensed chromatin states. HP1α localization to heterochromatic regions is mediated by its binding to specific repressive marks on the tail of histone H3, such as trimethylated lysine 9 on histone H3 (H3K9me3).

Modified histone peptides uniquely tune the material properties of HP1α condensates.

Biomolecular condensates have emerged as a powerful new paradigm in cell biology with broad implications to human health and disease, particularly in the nucleus where phase separation is thought to underly elements of chromatin organization and regulation. Specifically, it has been recently reported that phase separation of heterochromatin protein 1alpha (HP1α) with DNA contributes to the formation of condensed chromatin states. HP1α localization to heterochromatic regions is mediated by its binding to specific repressive marks on the tail of histone H3, such as trimethylated lysine 9 on histone H3 (H3K9me3).

Localized and regulated peptide pigment formation inside liquid droplets through confined enzymatic oxidation.

Melanin pigments are found in most life forms, where they are responsible for coloration and ultraviolet (UV) light protection. Natural melanin is a poorly soluble and complex biosynthesis product produced through confined and templated enzymatic oxidation of tyrosine. It has been challenging to create water-soluble synthetic mimics.

Liquid to solid transition of elastin condensates.

Liquid-liquid phase separation of tropoelastin has long been considered to be an important early step in the complex process of elastin fiber assembly in the body and has inspired the development of elastin-like peptides with a wide range of industrial and biomedical applications. Despite decades of study, the material state of the condensed liquid phase of elastin and its subsequent maturation remain poorly understood. Here, using a model minielastin that mimics the alternating domain structure of full-length tropoelastin, we examine the elastin liquid phase.

Methods and Strategies to Quantify Phase Separation of Disordered Proteins.

Phase separation has emerged as a new paradigm currently revolutionizing our understanding of cell biology and intracellular organization. Disordered protein domains have recently been demonstrated as integral drivers of phase separation into condensed liquids with emergent material properties. Using in vitro model systems employing purified protein components is necessary to interrogate the molecular mechanisms underlying phase separation; however, these systems pose many experimental challenges.

Retraction of DNA-bound type IV competence pili initiates DNA uptake during natural transformation in Vibrio cholerae.

Natural transformation is a broadly conserved mechanism of horizontal gene transfer in bacterial species that can shape evolution and foster the spread of antibiotic resistance determinants, promote antigenic variation and lead to the acquisition of novel virulence factors. Surface appendages called competence pili promote DNA uptake during the first step of natural transformation ; however, their mechanism of action has remained unclear owing to an absence of methods to visualize these structures in live cells. Here, using the model naturally transformable species Vibrio cholerae and a pilus-labelling method, we define the mechanism for type IV competence pilus-mediated DNA uptake during natural transformation.