Current Protein and Peptide Science - Volume 21, Issue 10, 2020

Infectious diseases caused by viruses have become a serious public health issue in the recent past, including the current pandemic situation of COVID-19. Enveloped viruses are most commonly known to cause emerging and recurring infectious diseases. Viral and cell membrane fusion is the major key event in the case of enveloped viruses that is required for their entry into the cell. Viral fusion proteins play an important role in the fusion process and in infection establishment. Because of this, the fusion process targeting antivirals become an interest to fight against viral diseases caused by the enveloped virus. Lower respiratory tract infections casing viruses like influenza, respiratory syncytial virus (RSV), and severe acute respiratory syndrome coronavirus (SARS-CoV) are examples of such enveloped viruses that are at the top in public health issues. Here, we summarized the viral fusion protein targeted antiviral peptides along with their mechanism and specific design to combat the viral fusion process. The pandemic COVID-19, severe respiratory syndrome disease is an outbreak worldwide. There are no definitive drugs yet, but few are in on-going trials. Here, an approach of fragmentbased drug design (FBDD) methodology is used to identify the broad spectrum agent target to the conserved region of fusion protein of SARS CoV-2. Three dipeptides (DL, LQ and ID) were chosen from the library and designed by the systematic combination along with their possible modifications of amino acids to the target sites. Designed peptides were docked with targeted fusion protein after energy minimization. Results show strong and significant binding affinity (DL = -60.1 kcal/mol; LQ = - 62.8 kcal/mol; ID= -71.5 kcal/mol) during interaction. Anyone of the active peptides from the developed libraries may help to block the target sites competitively to successfully control COVID-19.

Background: The neuroinflammatory process is associated with the pathogenesis of many cardiovascular disorders, particularly with hypertension. In this regard, the deficiency of vitamin D seems to increase the risk of cardiovascular pathologies related to neuroinflammation. Long-term lack of vitamin D leads to over-activation of the renin-angiotensin-aldosterone system (RAAS), one of the essential mechanisms of blood pressure regulation. Purpose of Review: This review summarizes the latest studies carried out to evaluate the primary mechanisms underlying the neuroprotective effect of vitamin D and its receptors (VDR) in the central nervous system. Besides, the present article condenses the evidence supporting the link between vitamin D and the RAAS in hypertension and neuroinflammation. Highlights Standpoints: Vitamin D deficiency is highly prevalent in the world, and the rising prevalence of neuroinflammatory diseases and associated pathologies such as hypertension around the world justifies the urgent need of searching new and more effective therapeutic methods that could be related to RAAS modulation and vitamin D levels management.

Ghrelin is a 28-amino acid octanoylated peptide hormone that is implicated in many physiological and pathophysiological processes. Specific visualization of ghrelin and its cognate receptor using traceable ligands is crucial in elucidating the localization, functions, and expression pattern of the peptide’s signaling pathway. Here 12 representative radio- and fluorescently-labeled peptide-based ligands are reviewed for in vitro and in vivo imaging studies. In particular, the focus is on their structural features, pharmacological properties, and applications in further biochemical research.

Locating remedies for Alzheimer’s disease (AD) has been majorly restricted by the inefficiency to establish a definitive detection model for early-stage diagnosis of pathological events. This current lapse in AD diagnosis also limits the therapeutic efficiency of the drugs, which might have been effective if given at the earlier stages of the disease. The indicated situation directs towards the burgeoned need for an effective biomarker technique that will help in early detection of AD and would be imminently useful to facilitate improved diagnosis and stimulate therapeutic trials. Till date, the major biomarkers, specifically associated with AD detection, may help in determining the early-stage AD diagnosis and identifying alterations in the cellular proteome, offering deeper insight into disease etiology. Currently existing multidisciplinary clinical diagnosis of AD is a very tedious, expensive procedure and requires highly trained and skilled professionals who are rarely available outside the specialty clinics. Mutations in amyloid precursor protein (APP) or Presenilin 1 and 2 (PSEN1 and PSEN2) are some biomarkers acting as critical checkpoints for AD diagnosis. However, the presence of some associated biomarkers in cerebrospinal fluid (CSF) such as total-Tau (tTau), phosphorylated- Tau (pTau) 181 and Amyloid-β (Aβ) 1-42 using structural or functional imaging techniques is considered for confirmatory diagnosis of AD. Furthermore, the molecular diagnosis of AD incorporates various sophisticated techniques including immuno-sensing, machine learning, nano conjugation-based detections, etc. In the current review description, we have summarized the various diagnostic approaches and their relevance in mitigating the long-standing urgency of targeted diagnostic tools for detection of AD.

Serotonin (5-hydroxytryptamine, 5-HT) has been recognized as a potent pro-inflammatory mediator. Increasing the bioavailability and preventing the formation of 5-HT can reduce the inflammatory response in the body. Moreover, 5-HT is considered as an important central physiologic mediator of intestinal function by regulating intestinal motility, permeability, and other functions. The dysfunction of intestinal serotonergic system causes intestinal barrier damage and further leads to the increase of bacterial endotoxin (LPS) translocation into the liver, which contributes to the development of non-alcoholic fatty liver disease (NAFLD). In addition, increasing the expression of serotonin reuptake transporter (SERT) and decreasing the expression of tryptophan hydroxylase1 (TPH1) can relieve the symptoms of NAFLD. Tryptophan (TRP), as a precursor of 5-HT synthesis, plays an important role in gut homeostasis and energy metabolism. Previous studies have found that TRP supplementation aggravates fatty liver degeneration by producing 5-HT, which activates mTOR signaling pathway in mice fed a high fat and high fructose diet. However, recent researches reveal that TRP supplementation stabilizes the intestinal barrier damage by increasing the expression of occludin and reduces the accumulation of fatty acids in liver. Although the effects of TRP supplementation on NAFLD are not clear and the specific mechanism needs to be further explored. A better understanding of the mechanisms of 5-HT on the liver and gut may open new therapeutic strategies in NAFLD.

Transient receptor potential melastatin 7 (TRPM7), along with the closely related TRPM6, are unique channels that have dual operations: cation permeability and kinase activity. In contrast to the limited tissue distribution of TRPM6, TRPM7 is widely expressed among tissues and is therefore implicated in a variety of cellular functions physiologically and pathophysiologically. The discovery of TRPM7’s unique structure imparting dual ion channel and kinase activities shed light onto novel and peculiar biological functions, such as Mg2+ homeostasis, cellular Ca2+ flickering, and even intranuclear transcriptional regulation by a cleaved kinase domain translocated to nuclei. Interestingly, at a higher level, TRPM7 participates in several biological processes in the nervous and cardiovascular systems, in which excitatory responses in neurons and cardiomyocytes are critical for their function. Here, we review the roles of TRPM7 in cells involved in the nervous and cardiovascular systems and discuss its potential as a future therapeutic target.

Ligand-linked changes in the aggregation state of biological macromolecules occur and have importance in several physiological processes, e.g., the response of hormone receptors, cooperative ligand binding, and others. The mathematical formalisms that express the thermodynamics governing these processes are complex, as they are required to describe observations made under experimental conditions in which many parameters may be simultaneously varied. The description of the functional behaviour of proteins that present ligand-linked association-dissociation events must accommodate cases where both the binding stoichiometries and reaction mechanisms are variable. In this paper, we review some paradigmatic cases that cover different structural arrangements and binding modes, with special attention to the case of dissociating homodimeric transport proteins and receptors. Even though we cannot pretend to be comprehensive on the proteins presenting this behaviour, we believe that we can attempt to be comprehensive on the structural arrangements and thermodynamic properties of these systems, which fall into a limited set of possible types.

Aminoglycosides and β-lactams are the most commonly used antimicrobial agents in clinical practice. This occurs because they are capable of acting in the treatment of acute bacterial infections. However, the effectiveness of antibiotics has been constantly threatened due to bacterial pathogens producing resistance enzymes. Among them, the aminoglycoside-modifying enzymes (AMEs) and β-lactamase enzymes are the most frequently reported resistance mechanisms. AMEs can inactivate aminoglycosides by adding specific chemical molecules in the compound, whereas β-lactamases hydrolyze the β-lactams ring, preventing drug-target interaction. Thus, these enzymes provide a scenario of multidrug-resistance and a significant threat to public health at a global level. In response to this challenge, in recent decades, several studies have focused on the development of inhibitors that can restore aminoglycosides and β-lactams activity. In this context, peptides appear as a promising approach in the field of inhibitors for future antibacterial therapies, as multiresistant bacteria may be susceptible to these molecules. Therefore, this review focused on the most recent findings related to peptide-based inhibitors that act on AMEs and β-lactamases, and how these molecules could be used for future treatment strategies.

Indoleamine 2, 3-dioxygenase 1 (IDO1) is the only rate-limiting enzyme outside the liver that catalyzes the oxidation and cracking of indole rings in the tryptophan along the kynurenine pathway (KP). The overactivation of IDO1 is closely related to the pathogenesis of various human immune and neurological diseases. As an important target for the treatment of many human serious diseases, including malignant tumors, the development of IDO1 inhibitors is of great practical significance. In this work, the structure and function of IDO1 both are summarized from the aspects of the signal pathway, catalytic mechanism, structural biology, and so on. Moreover, the current development status of IDO1 inhibitors is also systematically reviewed, which provides assistance for anti-cancer drug design based on the structure of receptors.