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SummaryAngiogenin (ANG) promotes cell growth and survival. Under growth conditions, ANG undergoes nuclear translocation and accumulates in the nucleolus where it stimulates rRNA transcription. When cells are stressed, ANG mediates the production of tRNA-derived stressinduced small RNA (tiRNA), which reprograms protein translation into a survival mechanism. The ribonucleolytic activity of ANG is essential for both processes but how this activity is regulated is unknown. We report here that ribonuclease/angiogenin inhibitor 1 (RNH1) controls both the localization and activity of ANG. Under growth conditions, ANG is located in the nucleus and is not associated with RNH1 so that the ribonucleolytic activity is retained to ensure rRNA transcription. Cytoplasmic ANG is associated with and inhibited by RNH1 so that random cleavage of cellular RNA is prevented. Under stress conditions, ANG is localized to the cytoplasm and is concentrated in stress granules where it is not associated with RNH1 and thus remains enzymatically active for tiRNA production. By contrast, nuclear ANG is associated with RNH1 in stressed cells to ensure that the enzymatic activity is inhibited and no unnecessary rRNA is produced to save anabolic energy. Knockdown of RNH1 abolished stress-induced relocalization of ANG and decreased cell growth and survival.

For the first time fish RNases have been isolated and characterized. Their functional and structural properties indicate that they belong to the RNase A superfamily (or tetrapod RNase superfamily), now more appropriately described as the vertebrate RNase superfamily. Our findings suggest why previously repeated efforts to isolate RNases from fish tissues have met with no success; fish RNases have a very low ribonucleolytic activity, and their genes have a low sequence identity with those of mammalian RNases. The investigated RNases are from the bony fish Danio rerio (or zebrafish). Their cDNAs have been cloned and expressed, and the three recombinant proteins have been purified to homogeneity. Their characterization has revealed that they have indeed a very low RNA-degrading activity, when compared with that of RNase A, the superfamily prototype, but comparable with that of mammalian angiogenins; that two of them have angiogenic activity that is inhibited by the cytosolic RNase inhibitor. These data and a phylogenetic analysis indicate that angiogenic fish RNases are the earliest diverging members of the vertebrate superfamily, suggesting that ribonucleases with angiogenic activity were the ancestors of all ribonucleases in the superfamily. They later evolved into both mammalian angiogenins and, through a successful phylogenesis, RNases endowed with digestive features or with diverse bioactivities.One of the largest and most studied superfamilies of proteins is that of extracellular, pyrimidine-specific, animal RNases. It has been labeled with different names on different bases: the "RNase A superfamily," a mostly historical name, recognizes bovine pancreatic RNase A, one of the most successfully investigated proteins, as the superfamily prototype; the "pancreatictype RNase superfamily," which includes not only the large family of RNases isolated from the pancreas of many animals but also all other RNases phylogenetically related to them; or "the tetrapod RNase superfamily," as to date the investigated members of this superfamily comprise RNases from mammals, birds, reptiles, and amphibians but not from fish (1).Some of the tetrapod RNases have diverse bioactivities, distinct from the ribonucleolytic activity, but strictly dependent on it, including immunosuppressive, cytotoxic, microbicidal, and angiogenic activity (2). The RNases with angiogenic activity, the angiogenins, form a distinct family within the superfamily and are identified by their ability to stimulate the growth of blood vessels (3, 4). Angiogenins with confirmed angiogenic activity, investigated so far only in mammals, are RNases characterized by a very low catalytic activity, albeit essential to their angiogenic activity, and the presence in their structure of only three disulfides, compared with the four disulfide bridges of most mammalian RNases (3-5).Studies carried out mostly with human angiogenin (hANG) 2 have indicated that hANG is recognized by a putative 170-kDa receptor on endothelial cells (6) and is translocated to the cell nucleus (...

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Cationic antimicrobial peptides (CAMPs) are a promising alternative to treat multidrug-resistant bacteria, which have developed resistance to all the commonly used antimicrobial, and therefore represent a serious threat to human health. One of the major drawbacks of CAMPs is their sensitivity to proteases, which drastically limits their half-life. Here we describe the design and synthesis of three nine-residue CAMPs, which showed high stability in serum and broad spectrum antimicrobial activity. As for all peptides a very low selectivity between bacterial and eukaryotic cells was observed, we performed a detailed biophysical characterization of the interaction of one of these peptides with liposomes mimicking bacterial and eukaryotic membranes. Our results show a surface binding on the DPPC/DPPG vesicles, coupled with lipid domain formation, and, above a threshold concentration, a deep insertion into the bilayer hydrophobic core. On the contrary, mainly surface binding of the peptide on the DPPC bilayer was observed. These observed differences in the peptide interaction with the two model membranes suggest a divergence in the mechanisms responsible for the antimicrobial activity and for the observed high toxicity toward mammalian cell lines. These results could represent an important contribution to unravel some open and unresolved issues in the development of synthetic CAMPs.

The importance of fish in vertebrate evolution has been better recognized in recent years after the intense work carried out on fish genomics. The recent discovery that fish genomes comprise homologs of ribonucleases, studied before only in tetrapods, and the isolation of ribonucleases from zebrafish have suggested an experimental model for studying fish and vertebrate evolution. Thus, the cDNAs encoding the RNases from the Atlantic salmon were expressed, and the recombinant RNases (Ss-RNase-1 and Ss-RNase-2) were isolated and characterized as both proteins and for their biological activities. Salmon RNases are less active than RNase A in degrading RNA, but are both sensitive to the action of the human cytosolic RNase inhibitor. The two enzymes possess both angiogenic and bactericidal activities. However, catalytically inactivated Ss-RNases do not exert any angiogenic activity, but preserve their full bactericidal activity, which is surprisingly preserved even when the enzyme proteins are fully denatured. Analyses of the conformational stability of the two RNases has revealed that they are as stable as typical RNases of the superfamily, and Ss-RNase-2, the most active as an enzyme, is also the most resistant to thermal and chemical denaturation. The implications of these findings in terms of the evolution of early RNases, in particular of the physiological significance of the angiogenic and bactericidal activities of fish RNases, are analyzed and discussed

Among bioactive peptides, cationic antimicrobial peptides (AMPs), also referred to as host defence peptides (HDPs), are valuable tools to treat infections, since they are able to kill a wide variety of microbes directly and/or to modulate host immunity. HDPs have great therapeutic potential against antibiotic-resistant bacteria, viruses and even parasites. However, high manufacturing costs have greatly limited their development as drugs, thus highlighting the need to develop novel and competitive production strategies. Here, a cost-effective procedure was established to produce the high amounts of peptides required for basic and clinical research. Firstly, a novel culture medium was designed, which was found to support significantly higher cell densities and recombinant expression levels of peptides under test compared to conventional media. The procedure has been also efficiently scaled up by using a 5 L fermenter, while the costs have been significantly lowered by developing a successful auto-induction strategy, which has been found to support significantly higher yields of target constructs and cell biomass compared to conventional strategies based on expression induction by IPTG. Interestingly, it was estimated that by increasing the production scale from 100 to 1,000 mg/batch, unit costs decreased strongly from 253 to 42 €/mg. These costs appear highly competitive when compared to chemical synthesis strategies. Altogether, the data indicate that the strategy represents an important starting point for the future development of large-scale manufacture of HDPs.

Multiwavelength anomalous dispersion (MAD) is the most widespread approach in structural biology for the determination of the crystal structure of a novel protein. Mass spectrometry is currently used to evaluate the selenomethionine (SeMet) content in solution, but excluding fluorescence spectroscopy at the absorption edge, no other routine method to check the SeMet incorporation and storage in the crystal state is yet available. Raman microscopy is an increasingly popular tool in physical biochemistry, with applications ranging from studies of ligand binding to secondary-structure analysis. Here, a novel methodological development is presented for the analysis via Raman microscopy of SeMet-labelled protein crystals to be used for MAD crystallography. The method is described and supported by validation and application to two novel proteins (a betagamma-crystallin-like protein and a DNA-binding protein). Markers of the SeMet residues are in the range 570-600 cm(-1), where proteins do not usually show Raman bands.