Project description:Challenging to engineer in synthetic glues, wet adhesion is critical for many technical and biomedical applications. Mussels, however, have evolved underwater glues that adhere effectively onto slippery seashore surfaces. Past research on mussel adhesion highlights the importance of the post-translationally modified amino acid 3,4-dihydroxyphenylalanine (DOPA), found in abundance in mussel glue proteins. Yet, DOPA alone is insufficient to match native adhesion in synthetic mimics. Here, we provide evidence that a previously uncharacterized histidine-rich protein (mefp-12) plays a crucial role in the formation, curing, and likely performance of mussel glue. Biochemical analysis localizes mefp-12 within the vesicles in the mussel glue secretory glands, while AI-assisted modeling of its sequence predicts Zn-stabilized coiled coil conformation and several domains resembling zinc-finger motifs. In vitro investigation of a His-rich 𝛼-helical peptide from mefp-12 shows Zn- and pH-dependent liquid-liquid phase separation (LLPS), coalescence, and spreading over the substrate. Exposure to seawater pH induces subsequent self-assembly of the fluid condensates into solid nanoporous networks resembling the structure of the native mussel glue. Based on these findings we gain a deeper mechanistic understanding of mussel glue formation and function that challenges the dominant DOPA-centric paradigm, providing new inspiration for design of bio-inspired wet adhesives.
Project description:Archaeological and archaeogenetic evidence points to the Pontic-Caspian steppe zone between the Caucasus and the Black Sea as the crucible from which the earliest steppe pastoralist societies arose and spread, ultimately influencing populations from Europe to Inner Asia. However, little is known about their economic foundations and the factors that may have contributed to their extensive mobility. Here we investigate the dental calculus proteomes of 45 individuals spanning the Neolithic to Greco-Roman periods in the Pontic-Caspian Steppe and neighboring South Caucasus, Oka-Volga-Don, and East Urals regions.
Project description:Biofilms are surface-adhered bacterial communities encased in an extracellular matrix composed of polysaccharides, proteins, and extracelluar (e)DNA, with eDNA being required for the formation and integrity of biofilms. Here we demonstrate that the spatial and temporal release of eDNA is regulated by BfmR, a regulator essential for Pseudomonas aeruginosa biofilm development. The expression of bfmR coincided with localized cell death and DNA release, with high eDNA concentrations localized to the outer part of microcolonies in the form of a ring and as a cap on small clusters. Additionally, eDNA release and cell lysis increased significantly following bfmR inactivation. Genome-wide transcriptional profiling indicated that bfmR was required for repression of genes associated with bacteriophage assembly and bacteriophage-mediated lysis. In order to determine which of these genes were directly regulated by BfmR, we utilized chromatin immunoprecipitation (ChIP) analysis to identify the promoter of PA0691, termed here phdA, encoding a previously undescribed homologue of the prevent-host-death (Phd) family of proteins. Lack of phdA expression coincided with impaired biofilm development, increased cell death and bacteriophage release, a phenotype comparable to ΔbfmR. Expression of phdA in ΔbfmR biofilms restored eDNA release, cell lysis, release of bacteriophages, and biofilm formation to wild type levels. Moreover, overexpression of phdA rendered P. aeruginosa resistant to lysis mediated by superinfective bacteriophage Pf4 which was only detected in biofilms. The expression of bfmR was stimulated by conditions resulting in membrane perturbation and cell lysis. Thus, we propose that BfmR regulates biofilm development by controlling bacteriophage-mediated lysis and thus, cell death and eDNA release, via PhdA.
Project description:Nasopharyngeal carcinoma (NPC) is a common cancer in southern China and South East Asia where more than 50,000 new cases are diagnosed each year. We used microarrays to identify down or upregulated genes in NPC compared with non-malignant controls. Experiment Overall Design: Snap frozen nasopharyngeal biopsies from 25 patients with histologically confirmed undifferentiated NPC were included in the microarray analysis. Controls were obtained from 3 patients with no evidence of malignancy.