Encapsulation and release of As pidasept peptides in polysaccharide formulation for oral application.

Due to the increase in bacterial resistance to common antibiotics and the lack of newly approved drugs, antimicrobial peptides (AMP) have been shown to be an alternative to combat infections caused by drug-resistant organisms. In particular, synthetic anti-lipopolysaccharide peptides (SALP) with the lead structure Aspidasept (Pep19-2.5) display a high anti-inflammatory activity in vitro and in vivo systems of endotoxemia and bacteremia. This was found not only when SALP were applied systemically (i.e. against sepsis), but also in topical therapies aimed at treating wound infections. A further important application involves combating common pathologies of the gastrointestinal tract, such as chronic infections of the small intestine and the colon (e.g., Crohn's disease). For the necessary oral application, the active pharmaceutical ingredient (API), Aspidasept®, must be encapsulated to ensure its protection against the low pH and the hydrolytic enzymes of the gastrointestinal tract. Here, the encapsulation of Aspidasept in polysaccharide matrices, essentially alginate and pectin, was systematically investigated with a variety of physico-chemical techniques. Specifically, we characterized key features of the nanoparticles such as their sizes and size distributions, as well as their stability in different environments mimicking digestive fluids. Finally, we studied the release of the drug from the polysaccharide matrices and the ability of nanoparticles to neutralize endotoxemia in vitro. We showed that our lead formulations exert an optimum inhibitory activity on immune cells stimulated by lipopolysaccharide.

Production of coronavirus nonstructural proteins in soluble form for crystallization.

For biophysical investigations on viral proteins, in particular for structure determination by X-ray crystallography, relatively large quantities of purified protein are necessary. However, expression of cDNAs coding for viral proteins in prokaryotic or eukaryotic systems is often not straightforward, and frequently the amount and/or the solubility of the protein obtained are not sufficient. Here, we describe a number of protocols for production of nonstructural proteins of coronaviruses that have proven to be efficient in increasing expression yields or solubilities.

Variable oligomerization modes in coronavirus non-structural protein 9.

Non-structural protein 9 (Nsp9) of coronaviruses is believed to bind single-stranded RNA in the viral replication complex. The crystal structure of Nsp9 of human coronavirus (HCoV) 229E reveals a novel disulfide-linked homodimer, which is very different from the previously reported Nsp9 dimer of SARS coronavirus. In contrast, the structure of the Cys69Ala mutant of HCoV-229E Nsp9 shows the same dimer organization as the SARS-CoV protein. In the crystal, the wild-type HCoV-229E protein forms a trimer of dimers, whereas the mutant and SARS-CoV Nsp9 are organized in rod-like polymers. Chemical cross-linking suggests similar modes of aggregation in solution. In zone-interference gel electrophoresis assays and surface plasmon resonance experiments, the HCoV-229E wild-type protein is found to bind oligonucleotides with relatively high affinity, whereas binding by the Cys69Ala and Cys69Ser mutants is observed only for the longest oligonucleotides. The corresponding mutations in SARS-CoV Nsp9 do not hamper nucleic acid binding. From the crystal structures, a model for single-stranded RNA binding by Nsp9 is deduced. We propose that both forms of the Nsp9 dimer are biologically relevant; the occurrence of the disulfide-bonded form may be correlated with oxidative stress induced in the host cell by the viral infection.

The non-structural protein Nsp10 of mouse hepatitis virus binds zinc ions and nucleic acids.

The non-structural protein Nsp10 of coronaviruses is a small cleavage product of the viral replicase polyprotein that has been implicated in RNA synthesis. Nsp10 of mouse hepatitis virus (MHV) displays an apparent molecular mass of 13-16kDa in reducing SDS-PAGE and analytical gel filtration, while dynamic light scattering suggests the existence of oligomeric forms. Atomic absorption spectroscopy reveals two metal ions per Nsp10 monomer, with a preference for Zn(2+) over Fe(2+/3+) and Co(2+). These are probably bound by two Zn-finger-like motifs. Moreover, MHV Nsp10 interacts with tRNA, single-stranded RNA, double-stranded DNA and, to a lesser extent, single-stranded DNA as shown by gel-shift experiments. The K(d) for tRNA is 2.1+/-0.2 microM.

Combination of serum eye drops with hydrogel bandage contact lenses in the treatment of persistent epithelial defects.

BACKGROUND: The treatment of persistent epithelial defects (PED) with autologous serum eye drops is often combined with conventional medication such as artificial tears and topical antibiotics, but until now no report exists on the use of a bandage contact lens (BCL) in combination with autologous serum eye drops in the treatment of PEDs. We report six eyes (five patients) which were all treated with autologous serum eye drops in combination with an FDA group IV hydrogel contact lens. METHODS: Five patients aged 36-88 years, were suffering from six PEDs for 73.5+/-46.9 days due to rheumatoid sterile corneal ulcer (n=1), neurotrophic keratopathy (n=3) or partial limbal stem cell deficiency (n=1). All patients had been unsuccessfully treated with conventional therapy before. Three of them had already had an amniotic membrane transplantation and two had undergone a keratoplasty; however, the epithelial defect persisted or recurred. In all cases, an FDA group IV hydrogel contact lens (Biomedics 55, ocufilcon D, 55% water content) was fitted and serum eye drops applied 8 times a day. RESULTS: The PED healed in five of six eyes after a treatment period of 14.2+/-8.9 days. In one eye the PED became smaller, but it took 90 days until the lesion healed completely. In three eyes (two patients) white deposits appeared on the surface of the BCL during the treatment after 12.3+/-5.1 days. Because no signs of inflammation were observed and since the epithelial defect improved, a new identical lens was applied and the medication continued unaltered. The surface of contaminated and non-contaminated BCLs were analyzed by scanning electron microscopy and SDS gel-electrophoresis. The scanning electron microscopic examination presented a coating of amorphous material with a wrinkled appearance and many corpuscular deposits. There was no indication of bacterial colonisation. The SDS gel-electrophoresis showed a small band at 65 kDa, probably albumin. CONCLUSION: These findings suggest that the combination of a therapeutic contact lens and serum eye drops can be successfully used in the treatment of persistent epithelial defects. Deposition of albumin may occur on the surface of the contact lenses, which, in the small group presented here, caused no unwanted effects.

The archaeal signal recognition particle: steps toward membrane binding.

Signal recognition particles and their receptors target ribosome nascent chain complexes of preproteins toward the protein translocation apparatus of the cell. The discovery of essential SRP components in the third urkingdom of the phylogenetic tree, the archaea (Woese, C. R., and Fox, G. E. (1977). Proc. Natl. Acad. Sci. U.S.A. 74, 5088-5090) raises questions concerning the structure and composition of the archaeal signal recognition particle as well as the functions that route nascent prepoly peptide chains to the membrane. Investigations of the archaeal SRP pathway could therefore identify novel aspects of this process not previously reported or unique to archaea when compared with the respective eukaryal and bacterial systems.

Novel functional aspects of the membrane-bound exo-pyrophosphatase of the hyperthermoacidophilic archaeon Sulfolobus are provided by analysis of its gene and the adjacent gene cluster.

The gene of the previously described plasma-membrane-bound acidic pyrophosphatase (exo-PPase) and adjacent genes of the hyperthermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) were cloned and sequenced. The 4-kb gene cluster comprises four open reading frames (sepp, simp, sabc, and satr) encoding the pyrophosphatase, a small hydrophobic protein of unknown cellular function, a hydrophilic ABC transport ATPase, and an amino transferase. The four proteins have deduced molecular masses of 21, 16, 34, and 48 kDa, respectively. Sepp, simp, and sabc are transcribed as monocistronic mRNAs from which sepp and sabc have been heterologously expressed by in vitro translation using reticulocyte lysates. The Sulfolobus acidocaldarius acidic exo-pyrophosphatase is a membrane-residing protein anchored with five transmembrane alpha-helices. Alignments with protein sequences from databases together with predictions of membrane topology reveal a novel group of proteins with the conserved phosphatase motif KxxxxxRP-(x12-54)-PSGH-(x31-54)-SRxxxxxHxxxD. For none of them a phosphatase or pyrophosphatase activity has yet been described except for the authentic Sulfolobus acidocaldarius protein. On the basis of these investigations a direct role of the exo-PPase in dolichyl phosphate or pyrophosphate hydrolysis and in resistance to the peptide antibiotic bacitracin is discussed.

Protein-protein, protein-RNA and protein-lipid interactions of signal-recognition particle components in the hyperthermoacidophilic archaeon Acidianus ambivalens.

The signal-recognition particle (SRP) of one of the most acidophilic and hyperthermophilic archaeal cells, Acidianus ambivalens, and its putative receptor component, FtsY (prokaryotic SRP receptor), were investigated in detail. A. ambivalens Ffh (fifty-four-homologous protein) was shown to be a soluble protein with strong affinity to membranes. In its membrane-residing form, Ffh was extracted from plasma membranes with chaotropic agents like urea, but not with agents diminishing electrostatic interactions. Using unilamellar tetraether phospholipid vesicles, both Ffh and FtsY associate independently from each other in the absence of other factors, suggesting an equilibrium of soluble and membrane-bound protein forms under in vivo conditions. The Ffh protein precipitated from cytosolic cell supernatants with anti-Ffh antibodies, together with an 7 S-alike SRP-RNA, suggesting a stable core ribonucleoprotein composed of both components under native conditions. The SRP RNA of A. ambivalens depicted a size of about 309 nucleotides like the SRP RNA of the related organism Sulfolobus acidocaldarius. A stable heterodimeric complex composed of Ffh and FtsY was absent in cytosolic supernatants, indicating a transiently formed complex during archaeal SRP targeting. The FtsY protein precipitated in cytosolic supernatants with anti-FtsY antisera as a homomeric protein lacking accessory protein components. However, under in vitro conditions, recombinantly generated Ffh and FtsY associate in a nucleotide-independent manner, supporting a structural receptor model with two interacting apoproteins.

Archaeal complex II: 'classical' and 'non-classical' succinate:quinone reductases with unusual features.

Reversible succinate dehydrogenase (SDH) activities have been ubiquitously detected in organisms from the three domains of life. They represent constituents either of respiratory complexes II in aerobes, or of fumarate dehydrogenase complexes in anaerobes. The present review gives a survey on archaeal succinate:quinone oxidoreductases (SQRs) analyzed so far. Though some of these could be studied in detail enzymologically and spectroscopically, the existence of others has been deduced only from published genome sequences. Interestingly, two groups of enzyme complexes can be distinguished in Archaea. One group resembles the properties of SDHs known from bacteria and mitochondria. The other represents a novel class with an unusual iron-sulfur cluster in subunit B and atypical sequence motifs in subunit C which may influence electron transport mechanisms and pathways. This novel class of SQRs is discussed in comparison to the so-called 'classical' complexes. A phylogenetic analysis is presented suggesting a co-evolution of the flavoprotein-binding subunit A and subunit B containing the three iron-sulfur clusters.