A structure filter for the Eukaryotic Linear Motif Resource

Background  

Many proteins are highly modular, being assembled from globular domains and segments of natively disordered polypeptides. Linear motifs, short sequence modules functioning independently of protein tertiary structure, are most abundant in natively disordered polypeptides but are also found in accessible parts of globular domains, such as exposed loops. The prediction of novel occurrences of known linear motifs attempts the difficult task of distinguishing functional matches from stochastically occurring non-functional matches. Although functionality can only be confirmed experimentally, confidence in a putative motif is increased if a motif exhibits attributes associated with functional instances such as occurrence in the correct taxonomic range, cellular compartment, conservation in homologues and accessibility to interacting partners. Several tools now use these attributes to classify putative motifs based on confidence of functionality.     

Chemical synthesis of cross-linked poly(KGGVG), an elastin-like biopolymer

Previous studies afforded on peptides and polypeptides containing repetitive sequences of elastin have largely demonstrated that their molecular and supramolecular properties are fully representative of those of tropoelastin, the soluble, linear precursor of elastin itself. In the attempt to synthesize cross-linked elastin-mimetic polypeptides, the repeating sequence VGGVG (V: valine; G: glycine), typical of elastin, was modified to incorporate lysine residues, yielding the polymer poly(KGGVG) (K: lysine). This imparts primary amine functionality susceptible to cross-linking reaction with appropriate bifunctional cross-linking reagents. We report herein the chemical synthesis and cross-linking of poly(KGGVG) with glutaraldehyde (GTA) and with disuccinimidyl glutarate (DSG). In both cases, the characterization of the polymers, both linear and cross-linked, has been carried out by CD spectroscopy and transmission electron microscopy measurements. The obtained results, although not conclusive, demonstrate that poly(KGGVG), both linear and cross-linked, may be considered very similar to tropoelastin and mature elastin, as concerns its molecular and supramolecular properties.     

Development of a new class of potential antiatherosclerosis agents: NO-donor antioxidants

A new class of NO-donor phenol derivatives is described. The products were obtained by joining appropriate phenols with either nitrooxy or 3-phenylsulfonylfuroxan-4-yloxy moieties. All the compounds proved to inhibit the ferrous salt/ascorbate induced lipidic peroxidation of membrane lipids of rat hepatocytes. They were also capable of dilating rat aorta strips precontracted with phenylephrine.     

Simultaneous production of triploid and haploid eggs by triploid Squalius alburnoides (Teleostei: Cyprinidae)

The hybrid minnow Squalius alburnoides comprises diploid and polyploid forms with altered modes of reproduction. In the present paper, we report a cross where a triploid female generated both large, triploid and small, haploid eggs simultaneously, which were fertilized with S. pyrenaicus sperm. Although the large eggs were rarer (15%), they originated offspring with higher survivorship, so that tetraploids were dominant among the surviving siblings. The cross yielded apparently all female progeny. Inheritance patterns were inferred using four microsatellite markers and NORs (Nucleolus Organizer Regions) phenotypes, and suggested that haploid eggs were probably produced by an atypical hybridogenesis, in which the elimination of the unmatched genome permitted random segregation and recombination between the homospecific genomes, while the triploid eggs were clonal. The present results suggest that the occurrence of triploid unreduced eggs may be a new route for the natural tetraploidization in the complex.     

Percutaneous closure of a coronary fistula between the right coronary artery to the left atrium

We describe a case of a congenital coronary artery fistula of the right coronary artery draining into the left atrium in an eight-year-old boy. The initial diagnosis was made after the detection of a continuous cardiac murmur at the age of six years. Transthoracic echocardiography showed the right coronaric ostium dilatation, the site of drainage in the left atrium and left ventricle volume overload. Catheterization confirmed the diagnosis. The patient underwent percutaneous closure by PDA occluder device. Immediate post-closure angiograms showed complete occlusion of the fistula. The patient showed transient ischemic changes on ECG associated to an increase of plasmatic levels of the cardiac enzyme. ECG and cardiac enzyme were normal one week after the procedure.     

Genomic Structure and Functional Analysis of Promoter Region of Somatolactin Gene of Sea Bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>)

Somatolactin (SL) is a pituitary hormone belonging to the growth hormone–prolactin family and is produced in the intermediate lobe of teleosts. The SL gene was isolated from a sea bream genomic library and found to be composed of 5 exons distributed within a 9-kb length of DNA. Sequence analysis of the proximal promoter region showed the presence of a classical TATA box located 59 bp upstream from the initial start ATG codon, 5 consensus sequences corresponding to the Pit-1 binding element, and a putative CREB site. In CHO cells cotransfected with the DNA from 2 plasmids, one encoding sea bream Pit-1 under Rous sarcoma virus long terminal repeat regulation and one encoding the SL promoter driving the expression of luciferase, Pit-1 was found to enhance the expression of luciferase. Only one Pit-1 binding site was necessary for enhancement. Analysis by immunoblots of in vitro culture of pituitaries of Sparus aurata showed that several agents, including estradiol, verapamil, and phorbol myristate acetate, had different inhibitory effects on SL and growth hormone released to the culture medium.     

AFM study of the elastin-like biopolymer poly(ValGlyGlyValGly)

In this paper, we report an AFM study on the supramolecular structures adopted by the synthetic polypentapeptide poly(ValGlyGlyValGly), whose monomeric sequence is an abundant, simple building block of elastin. The polypeptide was analyzed by deposition from both methanolic and aqueous suspensions, showing different behaviors. In methanol, the polypeptide is able to evolve, in a time-dependent way, from layers to ribbons to beaded filaments. When the equilibrium is reached, the formation of well-defined dendritic structures is also observed. This restructuring of the polypentapeptide seems to be reminiscent of a sort of Rayleigh instability. When deposited from aqueous suspensions, the polypeptide self-assembles either in fibrillar networks or in amyloid-like patterns, both of them being found in elastin or elastin-related polypeptides. As a general finding, poly(ValGlyGlyValGly) seems to constitute an excellent mimetic of the supramolecular properties of native elastin.     

Convenient preparation of L-arabino-hexos-5-ulose derivatives from lactose

2,6-di-O-benzyl- (9), 2-O-benzyl-3,4-O-isopropylidene- (19), and 2-O-benzyl-6-O-m-chlorobenzoyl-L-arabino-hexos-5-ulose (20) have been prepared using 4'-deoxy-4'-eno- and 6'-deoxy-5'-eno lactose dimethyl acetal derivatives 7 and 14 as key intermediates. The synthesis of enol ethers 7 and 14 has been performed with good yields by base-promoted elimination of acetone or p-toluenesulfonic acid from 2',6'-di-O-benzyl-, and 6'-O-p-toluenesulfonyl-2,3:5,6:3',4'-tri-O-isopropylidenelactose dimethyl acetal, respectively. The epoxidation with MCPBA of 7 and 14 in methanol or dichloromethane furnishes C-5'-methoxy and C-5'-m-chlorobenzoyloxy derivatives, easily transformed with good yields into L-arabino 5-ketoaldohexoses 9, 19 and 20.