Cation Diffusion Facilitators Transport Initiation and Regulation Is Mediated by Cation Induced Conformational Changes of the Cytoplasmic Domain

Cation diffusion facilitators (CDF) are part of a highly conserved protein family that maintains cellular divalent cation homeostasis in all domains of life. CDF's were shown to be involved in several human diseases, such as Type-II diabetes and neurodegenerative diseases. In this work, we employed a multi-disciplinary approach to study the activation mechanism of the CDF protein family. For this we used MamM, one of the main ion transporters of magnetosomes - bacterial organelles that enable magnetotactic bacteria to orientate along geomagnetic fields. Our results reveal that the cytosolic domain of MamM forms a stable dimer that undergoes distinct conformational changes upon divalent cation binding. MamM conformational change is associated with three metal binding sites that were identified and characterized. Altogether, our results provide a novel auto-regulation mode of action model in which the cytosolic domain's conformational changes upon ligand binding allows the priming of the CDF into its transport mode

NPT088 reduces both amyloid-b and tau pathologies in transgenic mice

Introduction: Alzheimer’s disease (AD) is characterized by appearance of both extracellular senile plaques and intracellular neurofibrillary tangles, comprised of aggregates of misfolded amyloid-b (Ab) and hyper-phosphorylated tau, respectively. In a previous study, we demonstrated that g3p, a capsid protein from bacteriophage M13, binds to and remodels misfolded aggregates of proteins that assume an amyloid conformation. We engineered a fusion protein (“NPT088”) consisting of the active fragment of g3p and human-IgG1-Fc. Methods: Aged Tg2576 mice or rTg4510 mice received NPT088 weekly via IP injection. Cognitive and/or functional motor endpoints were monitored during dosing. Pathology was quantified biochemically and immunohistochemically. Results: NPT088-lowered Ab plaque and improved cognitive performance of aged Tg2576 mice. Moreover, NPT088 reduced phospho-tau pathology, reduced brain atrophy, and improved cognition in rTg4510 mice. Discussion: These observations establish NPT088 as a novel therapeutic approach and potential drug class that targets both Ab and tau, the hallmark pathologies of AD

In Vivo Anti-Tumor Activity of Polypeptide HM-3 Modified by Different Polyethylene Glycols (PEG)

HM-3, designed by our laboratory, is a polypeptide composed of 18 amino acids. Pharmacodynamic studies in vivo and in vitro indicated that HM-3 could inhibit endothelial cell migration and angiogenesis, thereby inhibiting tumor growth. However, the half-life of HM-3 is short. In this study, we modified HM-3 with different polyethylene glycols (PEG) in order to reduce the plasma clearance rate, extend the half-life in the body, maintain a high concentration of HM-3 in the blood and increase the therapeutic efficiency. HM-3 was modified with four different types of PEG with different molecular weights (ALD-mPEG5k, ALD-mPEG10k, SC-mPEG10k and SC-mPEG20k), resulting in four modified products (ALD-mPEG5k-HM-3, ALD-mPEG10k-HM-3, SC-mPEG10k-HM-3 and SC-mPEG20k-HM-3, respectively). Anti-tumor activity of these four modified HM-3 was determined in BALB/c mice with Taxol as a positive control and normal saline as a negative control. Tumor weight inhibition rates of mice treated with Taxol, HM-3, ALD-mPEG5k-HM-3, ALD-mPEG10k-HM-3, SC-mPEG10k-HM-3 and SC-mPEG20k-HM-3 were 44.50%, 43.92%, 37.95%, 31.64%, 20.27% and 50.23%, respectively. Tumor inhibition rates in the Taxol, HM-3 and SC-mPEG20k-HM-3 groups were significantly higher than that in the negative control group. The efficiency of tumor inhibition in the SC-mPEG20k-HM-3 group (drug treatment frequency: once per two days) was better than that in the HM-3 group (drug treatment frequency: twice per day). In addition, tumor inhibition rate in the SC-mPEG20k-HM-3 group was higher than that in the taxol group. We conclude that SC-mPEG20k-HM-3 had a low plasma clearance rate and long half-life, resulting in high anti-tumor therapeutic efficacy in vivo. Therefore, SC-mPEG20k-HM-3 could be potentially developed as new anti-tumor drugs

Profiling the selectivity of DNA ligases in an array format with mass spectrometry

This article describes a method for the global profiling of the substrate specificities of DNA ligases and illustrates examples using the Taq and T4 DNA ligases. The method combines oligonucleotide arrays, which offer the benefits of high throughput and multiplexed assays, with mass spectrometry to permit label-free assays of ligase activity. Arrays were prepared by immobilizing ternary biotin-tagged DNA substrates to a self-assembled monolayer presenting a layer of streptavidin protein. The array represented complexes having all possible matched and mismatched base pairs at the 3′ side of the nick site and also included a number of deletions and insertions at this site. The arrays were treated with ligases and adenosine triphosphate or analogs of the nucleotide triphosphate and then analyzed by matrix-assisted laser desorption-ionization mass spectrometry to determine the yields for both adenylation of the 5′-probe strand and joining of the two probe strands. The resulting activity profiles reveal the basis for specificity of the ligases and also point to strategies that use ATP analogs to improve specificity. This work introduces a method that can be applied to profile a broad range of enzymes that operate on nucleic acid substrates

The Potential of Antimicrobial Peptides as Biocides

Antimicrobial peptides constitute a diverse class of naturally occurring antimicrobial molecules which have activity against a wide range of pathogenic microorganisms. Antimicrobial peptides are exciting leads in the development of novel biocidal agents at a time when classical antibiotics are under intense pressure from emerging resistance, and the global industry in antibiotic research and development stagnates. This review will examine the potential of antimicrobial peptides, both natural and synthetic, as novel biocidal agents in the battle against multi-drug resistant pathogen infections