Springer Science and Business Media LLC

Due to increasing resistance of bacteria to traditional antibiotics, antimicrobial peptides are being investigated as a promising alternative. Tachyplesin, an antimicrobial peptide isolated from horseshoe crab, inhibits the growth of many different types of bacteria with its ability to permeabilize the cell membrane. Starting with a previously reported linear tachyplesin analog lacking cysteine (cysteine-deleted tachyplesin, CDT, KWFRVYRGIYRRR-CONH2), this study examines the systematic deletion of the C-terminal arginines and the N-terminal lysine, addition of positively charged N-and C-terminal residues, replacement of arginine with similarly-charged lysine, and replacement of hydrophobic residues with aliphatic, aromatic, fluoro-substituted aromatic, and bicyclic amino acids to examine effects on activity. The 16 modified CDT analogs were tested for their ability to disrupt model liposomes, and minimum inhibitory concentrations were determined for gram-positive and gram-negative bacterial strains. Hemolytic activity also was assessed. Overall, results indicate that elimination of two C-terminal arginine residues results in a peptide ([des-Arg12,13]CDT) with preserved antimicrobial activity but a reduction in hemolysis, a selectivity desirable for a therapeutic agent. Additional deletion was not tolerated, nor was addition of residues at the termini. Analysis of the 16 analogs also reveals the importance of hydrophobicity, not necessarily aromaticity, as an analog with hydrophobic isoleucine residues placed throughout the sequence ([Ile2,3,6,10]CDT) displayed comparable antimicrobial activity to CDT with lower hemolysis, representing a promising antimicrobial peptide with lowered toxicity.

Klebsiella pneumoniae is a Gram-negative opportunistic pathogen that causes bacteremia, meningitis, endocarditis, cellulitis, urinary tract infections. The emergence of antibiotic resistance in this pathogen makes the infection of K. pneumoniae more dangerous. Therefore, it is the need of hour to use the advanced technologies for developing vaccines, which can surpass the traditional methods used for treating the infections. In our study, we have considered designing multi-epitope based vaccines targeting the outer membrane proteins of K. pneumoniae. The proteome of K. pneumoniae was analysed using subtractive proteomics, and reverse vaccinology. In subtractive proteomics, the proteins were sorted on the basis of SignalP, TatP, LIPOP, Transmembrane helicity (TMHMM, HMMTOP), and cellular localization (CELLO and PSORTb). Fifteen outer membrane protein were selected that had the potential for the multi-epitope based vaccine designing. The MHC I, MHC II, B cell interacting epitopes of these proteins, which could generate a decent cellular and humoral immune responses in the host cell, were analysed. On this basis, four vaccine constructs (VK1 to VK4) were analyzed for their antigenicity, allergenicity, solubility, and physicochemical properties. Out of these constructs, VK2 was modeled using RapotorX server and docked (PatchDock) with different HLA alleles, and its molecular dynamics was also studied. These analysis showed that VK2 multi-epitope vaccine could be a suitable target to control the K. pneumoniae infections.

To answer the question of whether the conformation of the Leu-Pro bond is cis or trans in Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH2 when complexed with the SH2 domain of Stat3, we substituted 2,2-dimethyloxazolidines derived from serine (Ser(ΨMe,Mepro)) and threonine (Thr(ΨMe,Mepro)) for proline. The 2,2-dimethyloxazolidine and 2,2-dimethylthiazolidine pseudoproline (ΨPro) analogs induce predominantly cis Xxx-ΨPro peptide bonds. As these ΨPro analogs are acid-labile, the phosphopeptides were synthesized using Fmoc-based SPPS using unprotected phosphotyrosine and 4-hydroxybenzoate as the linker that allowed release from the support by alkaline ammonolysis, conditions that kept the oxazolidine rings intact. Incorporation of Ser(ΨMe,Mepro) resulted in 69% cis Leu-ΨPro bond content in aqueous solution whereas that for Thr(ΨMe,Mepro) analog was 63%. Affinities for Stat3 were 3–5 fold lower than the lead compound and were inversely correlated with cis content. Thus we conclude that the Leu-Pro peptide bond is trans when the peptide is bound to Stat3.

Sepsis, a result of a hyperreaction of the immune system to acute infection, has been recognized as a significant healthcare challenge due to the considerable associated morbidity and mortality. In this study, the antisepsis effects of bovine lactoferrin (bLF) and metoprolol were evaluated in a lipopolysaccharide (LPS)-induced sepsis model in mice. Eighty mice were divided into two equal groups and received LPS or PBS inoculation. Prior to LPS/PBS inoculation, each group was further divided into four equal groups to receive saline solution (SS), metoprolol, bLF, or bLF + metoprolol. Mouse survival was monitored at 0, 3, 24, 48 and 96 h after LPS/PBS inoculation, and blood was collected for inflammatory cytokine and lactate measurements. Morphological and structural changes in vital organs, such as the heart, kidney, and liver, were recorded. The survival rates of septic mice treated with metoprolol, bLF, and bLF + metoprolol significantly improved compared to those of mice treated with SS. The levels of inflammatory cytokines and lactate decreased in the bLF and bLF + metoprolol groups, and tissue injury was diminished in all groups compared with septic LPS-SS mice. This study shows an antisepsis effect of bLF against LPS-induced sepsis in mice, an effect that is boosted in combination with metoprolol, indicating a novel option to prevent or treat sepsis.

The original version of this article unfortunately contained a typo in the author name. The co-author name should be Khalil K.Y. Saleh instead it was published as Klalil K.Y. Saleh.

Many antimicrobial peptides (AMPs) have multiple antimicrobial immunity effects. One such class of peptides is temporins. Temporins are the smallest (AMPs) found in nature and are highly active against gram-positive bacteria. Nowadays, there was a rapid increase in the availability of the 3D structure of proteins in PDB (protein data bank). The conserved residues and 3D structural conformations of temporins (AMPs) were still unknown. The present study explores the sequence analysis, alpha-helical structural conformations of temporins. The sequence of temporins was deracinated from APD3 database, the three-dimensional structure was constructed by homology modeling studies. The sequence analysis results show that the conserved residues among the peptide sequences, the maximum of the sequences are 70% alike to each other. The secondary structure prediction results revealed that 99% of temporin (AMPs) exhibited in alpha-helical form. The 3D structure speculated using RAMPAGE exposes the alpha-helical conformation in all temporins (AMPs). The phylogenetic analysis reveals the evolutionary relationships of temporins (AMPs), which are branched into seven clusters. As a result, we identified a list of potential temporin AMPs which docked to the antiviral protein (MERS-CoV), it shows good protein-peptide binding. This computational approach may serve as a good model for the rationale design of temporin based antibiotics.

CuSO4 was used and created an in-vivo inflammatory model of a zebrafish embryo for drug testing in this work. In our study, molecular docking was performed to check the possible polar interaction with the peptide, TL15 of sulphite reductase derived from spirulina (Arthrospira plantensis) and the COX-2, which is predicted to have anti-inflammatory activity. In-vitro anti-inflammatory activity was performed on human erythrocytes, and the potential activity of TL15 peptide was in a concentration-dependent manner. We further investigated the technique for evaluating the anti-inflammatory effects of TL15. To produce acute inflammation, the zebrafish (Danio rerio) larvae were treated with CuSO4 at 2 μM and toxicity analysis were done at 0–96 hpf. The effect of TL15 was analysed upon treatment to CuSO4 induced larvae at dose-dependent manner (10–80 μM) and exhibited a gradual reduction in oxidative stress at 80 μM TL15. Macrophages were monitored using neutral red labelling after CuSO4 stimulation; as the major end-point, larval mortality was employed. RT-PCR was used to assess the expression level of important cytokines implicated in the inflammatory response, such as COX-2, TNF-α, IL-1β and IL-10. Within 24 h, CuSO4 increased mortality in a dose-dependent process. The increment in the inflammatory response due to CuSO4 induction in zebrafish larvae was demonstrated by analysing the COX-2, IL-1β, IL-10 and TNF-α expression. In addition, we also investigated the reactive oxygen species scavenging activity of TL15 on CuSO4 induced larvae by analysing the GST and GPX expression levels in the zebrafish embryo. Overall, TL15 of sulphite reductase was found to have a potent anti-inflammatory activity by scavenging the free radical productions.

Cell-penetrating peptides have proven themselves as valuable vectors for intracellular delivery. Relatively little is known about the frequency of cell-penetrating sequences in native proteins and their functional role. By computational comparison of peptide sequences, we recently predicted that intracellular loops of G-protein coupled receptors (GPCR) have high probability for occurrence of cell-penetrating motifs. Since the loops are also receptor and G-protein interaction sites, we postulated that the short cell-penetrating peptides, derived from GPCR, when applied extracellularly can pass the membrane and modulate G-protein activity similarly to parent receptor proteins. Two model systems were analyzed as proofs of the principle. A peptide based on the C-terminal intracellular sequence of the rat angiotensin receptor (AT1AR) is shown to internalize into live cells and elicit blood vessel contraction even in the presence of AT1AR antagonist Sar1-Thr8-angiotensin II. The peptide interacts with the same selectivity towards G-protein subtypes as agonist-activated AT1AR and blockade of phospholipase C abolishes its effect. Another cell-penetrating peptide, G53-2 derived from human glucagon-like peptide receptor (GLP-1R) is shown to induce insulin release from isolated pancreatic islets. The mechanism was again found to be shared with the original GLP-1R, namely G11-mediated inositol 1,4,5-triphosphate release pathway. These data reveal a novel possibility to mimic the effects of signalling transmembrane proteins by application of shorter peptide fragments.

Peptides mimicking the biological properties of apolipoproteins have shown beneficial properties against a variety of diseases and have emerged as a potential candidate for their treatments. In this review, we have discussed the emerging field of apolipoprotein-mimetic peptides for clinical use. We have briefly discussed the latest in the field of development of high-density lipoprotein mimetics and apolipoprotein-A and apolipoprotein-E mimetic peptides. We primarily focused on the therapeutic potential of apolipoprotein-mimetic peptides in terms of their broad spectrum applications reported in pre-clinical and clinical studies. We conclude with a discussion on the emergence of apolipoprotein-mimetic peptides as potential candidates for the treatment of a broad spectrum of disorders.

Defects in liver peroxisomal alanine:glyoxylate aminotransferase (AGT), as a consequence of inherited mutations on the AGXT gene, lead to primary hyperoxaluria type I (PH1), a rare metabolic disorder characterized by the formation of calcium oxalate stones at first in the urinary tract and then in the whole body. The curative treatments currently available for PH1 are pyridoxine therapy, effective in only 10–30 % of the patients, and liver transplantation, an invasive procedure with potentially serious complications. A valid therapeutic option for PH1 patients would be the development of an enzyme administration therapy. However, the exogenous administration of the missing AGT would require the crossing of the plasma membrane to deliver the protein to liver peroxisomes. In this study, we constructed, purified and characterized the fusion protein of AGT with the membrane-penetrating Tat peptide (Tat-AGT). Although Tat-AGT shows subtle active site conformational changes as compared with untagged AGT, it retains a significant transaminase activity. Western-blot analyses, enzymatic assays and immunofluorescence studies show that active Tat-AGT can be successfully delivered to a mammalian cellular model of PH1 consisting of chinese hamster ovary cells expressing glycolate oxidase (CHO-GO), whereas untagged AGT cannot. Moreover, the intracellular transduced Tat-AGT makes CHO-GO cells able to detoxify endogenously produced glyoxylate to an extent similar to that of CHO-GO cells stably expressing AGT. Altogether, these results show that the Tat peptide is capable of delivering a functional AGT to mammalian cells, thus paving the way for the possibility to use Tat-AGT as an enzyme replacement therapy to counteract PH1.