Synthetic peptides that specifically bind nuclear hormone receptors offer an alternative approach to small molecules for the modulation of receptor signaling and subsequent gene expression. Here we describe the design of a series of novel stapled peptides that bind the coactivator peptide site of estrogen receptors. Using a number of biophysical techniques, including crystal structure analysis of receptor-stapled peptide complexes, we describe in detail the molecular interactions and demonstrate that all-hydrocarbon staples modulate molecular recognition events. The findings have implications for the design of stapled peptides in general.

The discovery of the new antibiotic teixobactin has been timely in the race for unearthing novel antibiotics wherein the emergence of drug resistance bacteria poses a serious threat worldwide. Herein, we present the total syntheses and biological activities of two teixobactin analogues. This approach is simple, efficient and has several advantages: it uses commercially available building blocks (except AllocHN-D-Thr-OH), has a single purification step and a good recovery (22). By using this approach we have synthesised two teixobactin analogues and established that the D-amino acids are critical for the antimicrobial activity of these analogues. With continuing high expectations from teixobactin, this work can be regarded as a stepping stone towards an in depth study of teixobactin, its analogues and the quest for synthesising similar molecules

Human angiogenin (ANG), the first member of the angiogenin family (from the pancreatic ribonuclease A superfamily) to be identified, is an angiogenic factor that induces neovascularization. It has received much attention due to its involvement in the growth of tumors and its elevated expression level in pancreatic and several other cancers. Recently the biological role of ANG has been shown to extend to the nervous system. Mutations in ANG have been linked with familial as well as sporadic forms of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder characterized by selective destruction of motor neurons. Furthermore, mouse angiogenin-1 has been shown to be expressed in the developing nervous system and during the neuronal differentiation of pluripotent stem cells. We have now characterized the seven variants of ANG reported in ALS patients with respect to the known biochemical properties of ANG and further studied the biological properties of three of these variants. Our results show that the ribonucleolytic activity of six of the seven ANG-ALS implicated variants is significantly reduced or lost and some variants also show altered thermal stability. We report a significant reduction in the cell proliferative and angiogenic activities of the three variants that we chose to investigate further. Our studies on the biochemical and structural features of these ANG variants now form the basis for further investigations to determine their role(s) in ALS.Amyotrophic lateral sclerosis (ALS) 1 is a fatal neurodegenerative disorder characterized by selective destruction of motor neurons (1). In the past decade, a small number of genes involved in the etiology of the disease have been identified (for a recent review see ref 2). The best studied of these is SOD1 (3), the gene for Cu/Zn superoxide dismutase. More than a hundred SOD1 mutations have now been linked with ALS, and motor neuron death from many of these mutations has been shown to result from a toxic gain of function rather than loss of dismutase activity. However, mutations in SOD1 account for only 1-2% of all cases of ALS and 20% of the familial cases. Some of the other proteins implicated in ALS are the vesicle-trafficking protein VAPB (4); ALSIN, a putative guanine nucleotide factor for GTPase (5); and senataxin (6). In addition, vascular endothelial growth factor (VEGF), an angiogenic factor that plays an important role in motor neuron survival, has been linked with ALS (7-10). However, the causes and molecular mechanisms underlying ALS are still largely unclear, and effective therapies do not appear to be imminent. Angiogenin (ANG), which encodes an angiogenic protein, was recently identified as a candidate susceptibility gene for ALS in the Irish and Scottish population by Greenway et al. (11). In a further study of over 2500 individuals from five independent populations from northern Europe and North America, Greenway et al. (12) found seven missense mutations (Figure 1) in 11 unrelated individuals with sporadic ALS and in f...

Leu10-teixobactin and Ile10-teixobactin have shown comparable activity to natural teixobactin.

Background: The precise role of the hemopexin domain of matrix metalloproteinase-1 (MMP-1) in collagenolysis is unknown. Results: The hemopexin domain collagen binding site is on ␤-propeller blades 1 and 2, and includes a Phe that is buried in the interface with the catalytic domain in the MMP-1 crystal structure. Conclusion: Domain dislocation is required for exosite exposure. Significance: MMP-1 may undergo significant domain rearrangements during collagenolysis.

The cyclic depsipeptide, teixobactin, kills a number of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), and Mycobacterium tuberculosis without detectable resistance. To date, teixobactin is the only molecule in its class that has shown in vivo antibacterial efficacy. In this work, we designed and synthesized 10 new in vivo ready teixobactin analogues. These analogues showed highly potent antibacterial activities against Staphylococcus aureus, MRSA, and vancomycin-resistant enterococci (VRE) in vitro. One analogue, d-Arg-Leu-teixobactin, 2, was found to be noncytotoxic in vitro and in vivo. Moreover, topical instillation of peptide 2 in a mouse model of S. aureus keratitis decreased the bacterial bioburden (>99.0% reduction) and corneal edema significantly as compared to untreated mouse corneas. Collectively, our results have established the high therapeutic potential of a teixobactin analogue in attenuating bacterial infections and associated severities in vivo.

The discovery of the highly potent antibiotic teixobactin, which kills the bacteria without any detectable resistance, has stimulated interest in its structure-activity relationship. However, a molecular structure-activity relationship has not been established so far for teixobactin. Moreover, the importance of the individual amino acids in terms of their l/d configuration and their contribution to the molecular structure and biological activity are still unknown. For the first time, we have defined the molecular structure of seven teixobactin analogues through the variation of the d/l configuration of its key residues, namely N-Me-d-Phe, d-Gln, d-allo-Ile and d-Thr. Furthermore, we have established the role of the individual d amino acids and correlated this with the molecular structure and biological activity. Through extensive NMR and structural calculations, including molecular dynamics simulations, we have revealed the residues for maintaining a reasonably unstructured teixobactin which is imperative for biological activity.

Matrix metalloproteinases (MMPs) regulate tissue remodeling, inflammation, and disease progression. Some soluble MMPs are inexplicably active near cell surfaces. Here, we demonstrate binding of MMP-12 directly to bilayers and cellular membranes using paramagnetic NMR and fluorescence. Opposing sides of the catalytic domain engage spin-labeled membrane mimics. Loops project from the β-sheet interface to contact the phospholipid bilayer with basic and hydrophobic residues. The distal membrane interface comprises loops on the other side of the catalytic cleft. Both interfaces mediate MMP-12 association with vesicles and cell membranes. MMP-12 binds plasma membranes and is internalized to hydrophobic perinuclear features, the nuclear membrane, and inside the nucleus within minutes. While binding of TIMP-2 to MMP-12 hinders membrane interactions beside the active site, TIMP-2-inhibited MMP-12 binds vesicles and cells, suggesting compensatory rotation of its membrane approaches. MMP-12 association with diverse cell membranes may target its activities to modulate innate immune responses and inflammation.