The interplay between noncollagenous proteins and biomineralization is widely accepted, yet the contribution of their secondary structure in mineral formation remains to be clarified. This study demonstrates a role for phosvitin, an intrinsically disordered phosphoprotein, in chick embryo skeletal development, and using circular dichroism and matrix least-squares Henderson-Hasselbalch global fitting, unravels three distinct pH-dependent secondary structures in phosvitin. By sequestering phosvitin on a biomimetic 3D insoluble cationic framework at defined pHs, access is gained to phosvitin in various conformational states. Induction of biomimetic mineralization at near physiological conditions reveals that a disordered secondary structure with a low content of P helix is remarkably efficient at promoting calcium adsorption, and results in the formation of biomimetic hydroxyapatite through an amorphous calcium phosphate precursor. By extending this finding to phosphorylated full-length human recombinant dentin matrix protein-1 (17-513 AA), this bioinspired approach provides compelling evidence for the role of a disordered secondary structure in phosphoproteins in bone-like apatite formation.

Trichilemmal cysts are common hair follicleederived intradermal cysts. The trait shows an autosomal dominant mode of transmission with incomplete penetrance. Here, we describe the pathogenetic mechanism for the development of hereditary trichilemmal cysts. By whole-exome sequencing of DNA from the blood samples of 5 affected individuals and subsequent Sanger sequencing of a family cohort including 35 affected individuals, this study identified a combination of the Phospholipase C Delta 1 germline variants c.903A>G, p.(Pro301Pro) and c.1379C>T, p.(Ser460Leu) as a high-risk factor for trichilemmal cyst development. Allele-specific PCRs and cloning experiments showed that these two variants are present on the same allele. The analysis of tissue from several cysts revealed that an additional somatic Phospholipase C Delta 1 mutation on the same allele is required for cyst formation. In two different functional in vitro assays, this study showed that the protein function of the cyst-specific 1-phosphatidylinositol 4, 5-bisphosphate phosphodiesterase delta-1 protein variant is modified. This pathologic mechanism defines a monoallelic model of the two-hit mechanism proposed for tumor development and other hereditary cyst diseases.

Phytochromes are important photoreceptors of plants, bacteria, and fungi responsive to light in the red and far-red spectrum. For increasing applications in basic research, synthetic biology, and materials sciences, it is required to recombinantly produce and purify phytochromes in high amounts. An ideal host organism for this purpose is E. coli due to its widespread use, fast growth, and ability for high-celldensity fermentation. Here, we describe the development of a generic platform for the production of phytochromes in E. coli that is compatible with high-cell-density fermentation. We exemplify our approach by the production of the photosensory domains of phytochrome B (PhyB) from A. thaliana and of the cyanobacterial phytochrome 1 (Cph1) from Synechocystis PCC 6803 in the multigram scale per 10 L fermentation run.

The heme protein myeloperoxidase is released from stimulated polymorphonuclear leukocytes, a cell species found in increasing amounts in the male and female genital tract of patients with genital tract inflammations. Myeloperoxidase binds only to a fraction of freshly prepared human spermatozoa. The number of spermatozoa able to bind myeloperoxidase raised considerably in samples containing pre-damaged cells or in acrosome-reacted samples. In addition, myeloperoxidase released from zymosan-stimulated polymorphonuclear leukocytes was also able to bind to pre-damaged spermatozoa. The ability of spermatozoa to bind myeloperoxidase coincided with the binding of annexin V to externalized phosphatidylserine epitopes indicating the loss of plasma membrane integrity and with the incorporation of ethidium homodimer I. Myeloperoxidase did not interact with intact spermatozoa. Annexin V and myeloperoxidase bind to the same binding sites as verified by double fluorescence techniques, flowcytometry analyses as well as competition experiments. We demonstrated also that myeloperoxidase is eluted together with pure phosphatidylserine liposomes or liposomes composed of phosphatidylserine and phosphatidylcholine in gel filtration, but not with pure phosphatidylcholine liposomes. In conclusion, myeloperoxidase interacts with apoptotic spermatozoa via binding to externalized phosphatidylserine indicating a yet unknown role of this protein in recognition and removal of apoptotic cells during inflammation.

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