A Novel RNA Aptamer as Synthetic Inducer of DasR Controlled Transcription.

Progress in the synthetic biology field is driven by the development of new tools for synthetic circuit engineering. Traditionally, the focus has relied on protein-based designs. In recent years, the use of RNA-based tools has tremendously increased, due to their versatile functionality and applicability.

The crystal structure of the varicella-zoster Orf24-Orf27 nuclear egress complex spotlights multiple determinants of herpesvirus subfamily specificity.

Varicella-zoster virus (VZV) is a human pathogen from the α-subfamily of herpesviruses. The VZV Orf24-Orf27 complex represents the essential viral core nuclear egress complex (NEC) that orchestrates the egress of the preassembled virus capsids from the nucleus. While previous studies have primarily emphasized that the architecture of core NEC complexes is highly conserved among herpesviruses, the present report focuses on subfamily-specific structural and functional features that help explain the differences in the autologous versus nonautologous interaction patterns observed for NEC formation across herpesviruses.

Structural and functional characterization of SiiA, an auxiliary protein from the SPI4-encoded type 1 secretion system from Salmonella enterica.

Salmonella invasion is mediated by a concerted action of the Salmonella pathogenicity island 4 (SPI4)-encoded type one secretion system (T1SS) and the SPI1-encoded type three secretion system (T3SS-1). The SPI4-encoded T1SS consists of five proteins (SiiABCDF) and secretes the giant adhesin SiiE. Here, we investigated structure-function relationships in SiiA, a non-canonical T1SS subunit.

Crystal Structure of the Extracellular Domain of the Human Dendritic Cell Surface Marker CD83.

CD83 is a type-I membrane protein and an efficient marker for identifying mature dendritic cells. Whereas membrane-bound, full-length CD83 co-stimulates the immune system, a soluble variant (sCD83), consisting of the extracellular domain only, displays strong immune-suppressive activities. Besides a prediction that sCD83 adopts a V-set Ig-like fold, however, little is known about the molecular architecture of CD83 and the mechanism by which CD83 exerts its function on dendritic cells and additional immune cells.

Identification of a Novel TGF-β-Binding Site in the Zona Pellucida C-terminal (ZP-C) Domain of TGF-β-Receptor-3 (TGFR-3).

The zona pellucida (ZP) domain is present in extracellular proteins such as the zona pellucida proteins and tectorins and participates in the formation of polymeric protein networks. However, the ZP domain also occurs in the cytokine signaling co-receptor transforming growth factor β (TGF-β) receptor type 3 (TGFR-3, also known as betaglycan) where it contributes to cytokine ligand recognition. Currently it is unclear how the ZP domain architecture enables this dual functionality.

Mouse ApoM displays an unprecedented seven-stranded lipocalin fold: folding decoy or alternative native fold?

Mouse apolipoprotein M (m-apoM) displays a 79% sequence identity to human apolipoprotein M (h-apoM). Both proteins are apolipoproteins associated with high-density lipoproteins, with similar anticipated biological functions. The structure of h-apoM has recently been determined by X-ray crystallography, which revealed that h-apoM displays, as expected, a lipocalin-like fold characterized by an eight-stranded β‑barrel that encloses an internal fatty-acid-binding site.

Computational design of a chain-specific tetracycline repressor heterodimer.

The specificity and selectivity of protein-protein interactions are of central importance for many biological processes, including signal transduction and transcription control. We used the in-house side-chain packing program MUMBO to computationally design a chain-specific heterodimeric variant of the bacterial transcription regulator tetracycline repressor (TetR), called T-A(A)B. Our goal was to engineer two different TetR chain variants, A and B, that no longer interact as AA or BB homodimers but selectively recombine to form heterodimers.

Vpx proteins of SIVmac239 and HIV-2ROD interact with the cytoskeletal protein alpha-actinin 1.

vpx genes of human immunodeficiency virus type 2 (HIV-2) and immunodeficiency viruses from macaques (SIVmac), sooty mangabeys (SIVsm) and red-capped mangabeys (SIVrcm) encode a 112 aa protein that is packed into virion particles via interaction with the p6 domain of p55(gag). Vpx localizes to the nucleus when expressed in the absence of other viral proteins. Moreover, Vpx is necessary for efficient nuclear import of the pre-integration complex (PIC) and critical for virus replication in quiescent cells, such as terminally differentiated macrophages and memory T cells.

Negative feedback loop of Wnt signaling through upregulation of conductin/axin2 in colorectal and liver tumors.

Activation of Wnt signaling through beta-catenin/TCF complexes is a key event in the development of various tumors, in particular colorectal and liver tumors. Wnt signaling is controlled by the negative regulator conductin/axin2/axil, which induces degradation of beta-catenin by functional interaction with the tumor suppressor APC and the serine/threonine kinase GSK3beta. Here we show that conductin is upregulated in human tumors that are induced by beta-catenin/Wnt signaling, i.