Marianna Tatarek-Nossol

A Hot-Segment-Based Approach for the Design of Cross-Amyloid Interaction Surface Mimics as Inhibitors of Amyloid Self-Assembly.

The design of inhibitors of protein-protein interactions mediating amyloid self-assembly is a major challenge mainly due to the dynamic nature of the involved structures and interfaces. Interactions of amyloidogenic polypeptides with other proteins are important modulators of self-assembly. Here we present a hot-segment-linking approach to design a series of mimics of the IAPP cross-amyloid interaction surface with Aβ (ISMs) as nanomolar inhibitors of amyloidogenesis and cytotoxicity of Aβ, IAPP, or both polypeptides. The nature of the linker determines ISM structure and inhibitory function including both potency and target selectivity. Importantly, ISMs effectively suppress both self- and cross-seeded IAPP self-assembly. Our results provide a novel class of highly potent peptide leads for targeting protein aggregation in Alzheimers disease, type 2 diabetes, or both diseases and a chemical approach to inhibit amyloid self-assembly and pathogenic interactions of other proteins as well.

Development of Accessible Peptidic Tool Compounds To Study the Phosphatase PTP1B in Intact Cells

Protein tyrosine phosphatases (PTPs) play crucial roles in health and disease. Chemical modulators of their activity are vital tools to study their function. An important aspect is the accessibility of these tools, which is usually limited or not existent due to the required, often complex synthesis of the molecules. We describe here a strategy for the development of cellular active inhibitors and in-cell detection tools for PTP1B as a model PTP, which plays important roles in diabetes, obesity, and cancer. The tool compounds are based on a peptide sequence from PTP1Bs substrate Src, and the resulting compounds are commercially accessible through standard peptide synthesis. The peptide inhibitor is remarkably selective against a panel of PTPs. We provide the co-crystal structure of PTP1B with the sequence from Src and the optimized peptide inhibitor, showing the molecular basis of the interaction of PTP1B with part of its natural substrate and explaining the crucial interactions to enhance binding affinity, which are made possible by simple optimization of the sequence. Our approach enables the broad accessibility of PTP1B tools to researchers and has the potential for the systematic development of accessible PTP modulators to enable the study of PTPs.

Peptide Inhibitors of the amyloidogenesis of IAPP: verification of the hairpin-binding geometry hypothesis.

Versions of a previously discovered β‐hairpin peptide inhibitor of IAPP aggregation that are stabilized in that conformation, or even forced to remain in the hairpin conformation by a backbone cyclization constraint, display superior activity as inhibitors. The cyclized hairpin, cyclo‐WW2, displays inhibitory activity at substoichiometric concentrations relative to this amyloidogenic peptide. The hairpin‐binding hypothesis stands confirmed.

A self-inhibitory interaction within Nup155 and membrane binding are required for nuclear pore complex formation

ABSTRACT Nuclear pore complexes (NPCs) are gateways through the nuclear envelope. How they form into a structure containing three rings and integrate into the nuclear envelope remains a challenging paradigm for coordinated assembly of macro-complexes. In vertebrates, the cytoplasmic and nucleoplasmic rings of NPCs are mostly formed by multiple copies of the Nup107–Nup160 complex, whereas the central, or inner ring is composed of Nup53, Nup93, Nup155 and the two paralogues Nup188 and Nup205. Inner ring assembly is only partially understood. Using in vitro nuclear assembly reactions, we show that direct pore membrane binding of Nup155 is crucial for NPC formation. Replacing full-length Nup155 with its N-terminal β-propeller allows assembly of the outer ring components to the NPC backbone that also contains Nup53. However, further assembly, especially recruitment of the Nup93 and Nup62 complexes, is blocked. Self-interaction between the N- and C-terminal domains of Nup155 has an auto-inhibitory function that prevents interaction between the N-terminus of Nup155 and the C-terminal region of Nup53. Nup93 can overcome this block by binding to Nup53, thereby promoting formation of the inner ring and the NPC. Highlighted Article: Membrane binding and an auto-inhibitory self-interaction within Nup155 is crucial for assembly of nuclear pore complexes in the nuclear envelope.