Processing of viral glycoproteins by the subtilisin-like endoprotease furin and its inhibition by specific peptidylchloroalkylketones

The spike glycoproteins of many enveloped viruses are proteolytically cleaved at the carboxytermini of sequences containing the basic motif R-X-K/R-R. Cleavage is often necessary for the fusion capacity of the glycoproteins and, thus, for virus infectivity. Among these viruses are pathogenic avian influenza viruses, human parainfluenza virus, human cytomegalovirus, and human immunodeficiency virus; it has been demonstrated that these viruses can be activated by furin. Indigenous furin has been identified in T-lymphocytes, which are host cells for HIV. Furin has been localized in the TGN and on the surface of cells after vectorial expression. Peptidylchloroalkylketones have been designed that inhibit with high specificity cleavage and fusion activity of viral glycoproteins, as well as virus replication.

Urodynamics in benign prostatic hyperplasia (BPH)

The simple pathophysiological concept of clinical BPH with a causal relationship between hyperplasia, obstruction, and specific symptoms does not hold up after a critical evaluation. The voiding function can nowadays be investigated comprehensively and differentiated utilizing modern urodynamic methods, and the function of the bladder outlet and the detrusor muscle can be evaluated quantitatively. Obstruction as a central term in clinical BPH can therefore be objectively documented. It can be shown that in a significant proportion of patients admitted for TURP with hyperplasia and symptoms of prostatism, no obstruction is present (over one-fourth of patients). The success rate of TURP in non-obstructed patients is worse than in obstructed patients; however, the subjective assessment of the surgical success is positive in the majority of patients. This holds true in a similar way for alternative treatment modalities (drug, balloon dilation, thermotherapy) after which the symptomatic success apparently is not associated with an objective reduction in obstruction. This lack of a definite correlation between symptoms and obstruction in BPH is open to many different interpretations. It is generally accepted that BPH without symptoms and obstruction or with obstruction but without symptoms may occur. It is, however, also true that aside from the highly selected patient population in this study with hyperplasia and symptoms and (suspected) obstruction, no data are available since urodynamic studies in patients with BPH but without symptoms are for obvious reasons not available. If we limit our thoughts to the few clear facts, it becomes evident that modern urodynamic methods can clearly distinguish between obstructive and non-obstructive symptomatic BPH. This introduces a new important standard of quality into BPH research requiring reassessment of currently available data. The simple urodynamics utilizing a flow rate recording as a convenient non-invasive diagnostic test is in widespread use and finds its proper place in the quick but non-specific documentation of bladder emptying function in clinical practice. Firm conclusions concerning the cause of a disturbed bladder emptying function are, however, not contained within the flow rate recording and can therefore not be abstracted from even the most refined methods to analyze the flow rate recording. The all-important parameter without which obstruction cannot be judged is the detrusor pressure during micturition. Since urodynamic pressure measurements are currently only possible as an invasive test, the indication for combined pressure flow measurements has to be considered carefully and the recording itself has to be conducted with appropriate expertise.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of two glycosylated boar spermadhesins

Boar spermadhesins AQN-1, AQN-3 and AWN form a recently described protein family, synthesized by the sexual accessory glands, and become associated with the sperm head upon ejaculation. They contain 109-133 amino acid residues, two conserved disulphide bridges, are not glycosylated, and have 40-60% primary structure identity. These boar polypeptides are multifunctional proteins, which possess heparin-, serine-protease-inhibitor- and/or zona-pellucida-glycoprotein-binding capability and have, therefore, been implicated in sperm capacitation and sperm-oocyte attachment. AQN-2 (18-20 kDa), however, is unique among boar spermadhesins in that it is the only member of the family which is known to be glycosylated and which possesses weak zona-pellucida-binding but not seminal-plasma-inhibitor-binding ability. In this study we report the structural and functional characterization of the two glycoproteins contained in the AQN-2 fraction. One component is identical with PSP-I, a major porcine seminal plasma protein whose function has not yet been identified, while the second protein is a glycosylated isoform of AQN-3. Here we show that the inability of the glycosylated boar spermadhesins to bind seminal-plasma protease inhibitors as well as the weak binding of glycosylated AQN-3 to zona pellucida glycoproteins is due to the presence of the oligosacharide chain on a conserved asparagine residue. This indicates that modification of a spermadhesin polypeptide framework may serve to modulate its ligand-binding capabilities.

Glycoprotein IIb peptide 656-667 mimics the fibrinogen gamma chain 402-411 binding site on platelet integrin GPIIb/IIIa

The human integrin glycoprotein IIb/IIIa complex plays a central role in haemostasis as an inducible receptor for fibrinogen and other adhesive proteins at the platelet plasma membrane. Current evidence indicates that the ligand-binding domain of GPIIb/IIIa is discontinuous and placed at the subunit interface. Here we show that a synthetic peptide containing the polypeptide stretch GPIIb 656-667, which is hidden within the resting platelet GPIIb/IIIa heterodimer but becomes exposed following platelet activation with thrombin, binds to soluble fibrinogen (n = 2.3 +/- 1.3; Kd = 2 +/- 0.8 x 10(-5) M). This interaction is Ca(2+)-independent and can be partially inhibited with synthetic fibrinogen gamma-chain peptide 400-411 but not with GRGDS. In addition, peptide GPIIb 656-667 inhibits in a dose-dependent manner the aggregation of activated platelets (IC50 = 170 microM). Altogether, our results indicate that the GPIIb 656-667 region may form part of the inducible fibrinogen binding site and may not overlap with the integrin RGD-recognition domain.

Secondary fungal metabolites and their biological activities, IV. Synthesis of compounds with structural similarities to the toxic metabolites of the pathogenic fungus Heterobasidion annosum and investigation of their antibiotic activities

A series of synthetic analogues of fomannoxin and fomajorin S, the toxic metabolites of the basidiomycete Heterobasidion annosum, was prepared in order to investigate which partial structures of the molecules are responsible for their biological activities. Of the compounds synthesized the five indane-2-acid derivatives 5-acetylindane-2-carboxylic acid (2), (+/-)5-formylindane-2-carboxylic acid (3), (+/-)indane-2,5-dicarboxylic acid (4), (+/-)formyl-2-methylindane-2-carboxylic acid (7) and 5-acetyl-indane-2,2-dicarboxylic acid (10) and 4-(2'-ethylbutyloxy)benzaldehyde (18) have not yet been described. Different biological test systems were employed to investigate the antibiotic activities of the synthesized analogues. The experimental results suggest that in the case of fomajorin S, the structural element essential for its toxicity is the 2-H- or 2-methylindane 2-acid. From the results obtained with the synthetic analogues of fomannoxin, it is now evident that the toxicity of this fungal metabolite can be attributed to an aromatic ring with a carbonyl or carboxyl substituent combined with a branched lipophilic side chain in p-substitution.

The Unexpected Reduction of the Vinyl Group of Chlorophyll b by Sodium Borohydride in Methanolic Extracts of Maize Leaves and Its Inhibition by 8-Hydroxyquinoline

During rapid extraction of chlorophylls from maize leaves under reducing conditions with methanol containing NaBH4, chlorophyll a remained unchanged but chlorophyll b yielded [7-hydroxymethyl]-chlorophyll b. The 3-vinyl group of chlorophyll b was also reduced forming significant am ounts, up to 60%, of [3-ethyl]-[7-hydroxymethyl]-chlorophyll b. This was unexpected since this reduction of the 3-vinyl group does not occur when isolated chlorophyll b is treated in an identical manner with methanolic borohydride. The vinyl-group of chlorophyll a is not reduced during the same extraction conditions suggesting that the presence of a formyl or hydroxyethyl group at C-7 is necessary. The presence of 8-hydroxyquinoline and NaBH4 in equimolar (16.5 m M) concentrations strongly inhibits the reduction of the 3-vinyl group of chlorophyll b in leaf extracts

Transient and stable gene expression in the fungal maize pathogen Cochliobolus heterostrophus after transformation with the beta-glucuronidase (GUS) gene

The bacterial GUS (beta-glucuronidase) gene has been used as a reporter gene in plants and bacteria and was recently expressed in filamentous fungi. Here, we report the application of GUS for the establishment of transient and stable gene expression systems in the phytopathogenic fungus Cochliobolus heterostrophus. The utility of the transient expression system is demonstrated in applications involving promoter analysis and in tests of various parameters of a transformation system, for comparing the rates of stable and transient transformation events using GUS as sole screening marker and for comparing different transformation systems using either GUS or a dominant selection marker. For these purposes two plasmids were constructed harbouring the GUS gene and the hph gene of Escherichia coli which confers resistance to the antibiotic hygromycin B (HygB), ligated either to the P1 or GPD1 (glyceraldehyde 3 phosphate dehydrogenase) promoter of C. heterostrophus. In transient expression studies the first appearance of GUS activity was observed within 2 h after transformation and maximal values were obtained after 7 or 10 h, depending on the promoter fused to the GUS gene. At peak activity, the GPD1 promoter was revealed to be five fold stronger than the P1 promoter. The same difference in promoter strength was observed when the vectors were stably integrated in the fungal genome. Using the GUS gene as a colour selection marker in plate assays, it was possible to detect transformants and monitor the process of transient gene expression visually. Blue transformants obtained by screening for the GUS phenotype were mitotically unstable. Transformants obtained by selecting for HygB resistance were mitotically stable and expressed the beta-glucuronidase gene constitutively.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective non-nucleoside HIV-1 reverse transcriptase inhibitors. New 2,3-dihydrothiazolo[2,3-a]isoindol-5(9bH)-ones and related compounds with anti-HIV-1 activity

A series of substituted 2,3-dihydrothiazolo[2,3-a]isoindol-5(9bH)-ones and related compounds 1-73 were synthesized and evaluated for their ability to inhibit reverse transcriptase (RT) of the human immune deficiency virus 1 (HIV-1) and replication of HIV-1 in MT2 cells. The antiviral activity of these compounds depends on the stereoselective configuration of the substituent in position 9b. Structure-activity studies were done within these series of compounds to determine the optimum substituents for antiviral activity. The most potent inhibitors were found in the class of 2,3-dihydrothiazolo[2,3-a]isoindol-5(9bH)-ones bearing a phenyl ring system in position 9b optionally substituted with one or two methyl groups or a chlorine atom in position 8. The most active analogues (R)-(+)-1, (R)-(+)-6, (R)-(+)-13, (R)-(+)-26, and (R)-(+)-53 inhibit the HIV-1 RT with an IC50 between 16 and 300 nM and an IC50 between 10 and 392 nM in MT2 cells, respectively.

Drosophila evolution challenges postulated redundancy in the E(spl) gene complex

The Enhancer of split [E(spl)] gene complex belongs to the class of neurogenic loci, which, in a concerted action, govern neurogenesis in Drosophila. Two genetically distinct functions, vital and neurogenic, reside within the complex defined by lethal mutations in the l(3) gro gene and by the typical neurogenic phenotype of deletions, respectively. Such deletions always affect several of the many embryonically active genes in the region, which cannot be mutated separately to lethality. Seven of these genes are extremely similar at the transcription and sequence level sharing the basic helix-loop-helix (bHLH) motif of transcriptional regulators. While these E(spl) bHLH genes seem to be required collectively for neurogenesis, they are nonessential individually, suggesting functional redundancy of the encoded gene products. No specific functions could yet be ascribed to any of the other genes located within the complex. One might expect these apparently dispensable genes, as well as the supposedly redundant bHLH genes, to be under little evolutionary constraint and, thus, to evolve most rapidly. However, we find the entire E(spl) gene complex highly conserved during Drosophila evolution, indicating that all the genes as well as their organization are of functional importance.

Derivation of the formyl-group oxygen of chlorophyll b from molecular oxygen in greening leaves of a higher plant (Zea mays)

Using mass spectroscopy, we demonstrate as much as 93% enrichment of the 7-formyl group oxygen of chlorophyll b when dark-grown, etiolated maize leaves are greened under white light in the presence of 18O2. This suggests that a mono-oxygenase is involved in the oxidation of its methyl group precursor. The concomitant enrichment of about 75% of the 13(1)-oxygen confirms the well-documented finding that this oxo group, in both chlorophyll a and b, also arises from O2. High 18O enrichment into the 7-formyl oxygen relative to the substrate 18O2 was achieved by optimization of the greening conditions in combination with a reductive extraction procedure. It indicates not only a single pathway for Chl b formyl group formation, but also unequivocally demonstrates that molecular oxygen is the sole precursor of the 7-formyl oxygen.

The role of cutinase in fungal pathogenicity

Cutinase, an extracellular fungal enzyme, is thought to be essential for the pathogenicity of certain fungal species to plants. Interpretations of recent data on fungal cutinase activity and pathogenicity are contradictory, and range from cutinase having no apparent influence on pathogenicity to it enhancing adhesion of fungal spores to the plant surface.

[Side reactions in peptide synthesis. V. O-sulfonation of serine and threonine during removal of pmc- and mtr-protecting groups from arginine residues in fmoc-solid phase synthesis]

A novel side reaction in Fmoc-solid-phase synthesis, which occurs during removal of protecting groups and detachment from the resin, was elucidated by investigations on model peptides: During the cleavage of Pmc- or Mtr-protecting groups from arginine residues by trifluoroacetic acid in peptides with O-tert-butyl-protected aliphatic hydroxyamino acids, peptides containing O3-sulfo-serine and O3-sulfo-threonine are formed as side-products in high yields, if suitable scavengers are absent. Subsequent to their isolation and purification, the structures of these peptide sulfuric acid mono-esters could unequivocally be proven by chemical and spectroscopic (MS, NMR, IR) methods.

The response of rat liver perisinusoidal lipocytes to polypeptide growth regulator changes with their transdifferentiation into myofibroblast-like cells in culture

During culture on uncoated plastic wells rat liver perisinusoidal lipocytes change their differentiated phenotype (transdifferentiate) within 1-2 weeks and obtain a myofibroblast-like phenotype (myofibroblast-like cells). This transdifferentiation was documented by morphologic (loss of fat droplets, flat cell shape, cytoplasmic extensions, expression of iso-alpha smooth muscle actin) and biochemical criteria (loss of retinyl-palmitate, enhanced matrix synthesis). Whereas transforming growth factor alpha (TGF alpha) stimulated and transforming growth factor beta (TGF beta 1) inhibited the proliferation of perisinusoidal lipocytes (early culture) these cytokines did not effect the growth of the myofibroblast-like cells. Opposite effects were obtained with platelet-derived growth factor (PDGF) which stimulated the growth of myofibroblast-like cells only. Insulin-like growth factor (IGF1) was mitogenic in both perisinusoidal lipocytes and myofibroblast-like cells, respectively. Furthermore, whereas the expression of the mRNAs of decorin and biglycan was stimulated by TGF beta 1 in perisinusoidal lipocytes, the synthesis of these mRNAs was stimulated in myofibroblast-like cells predominantly by TGF alpha. Similar effects of TGF alpha and TGF beta 1 have been observed on the glycosaminoglycan-([35S]sulfate incorporation) and proteoglycan level ([3H]leucin incorporation into decorin and biglycan). Neither IGF1 and PDGF stimulated glycosaminoglycan synthesis in perisinusoidal lipocytes or in myofibroblast-like cells. The results demonstrate that the effects of the polypeptide growth regulators TGF alpha, TGF beta 1 and PDGF depend on the cell phenotype (stage of cell activation/transdifferentiation) and may be completely different in perisinusoidal lipocytes and its transformed counterpart the myofibroblast-like cells.

Cloning and analysis of the mating type genes from Cochliobolus heterostrophus

Cochliobolus heterostrophus, a heterothallic Ascomycete, has a single mating type locus with two alternate forms called MAT-1 and MAT-2. MAT-1 was cloned by complementing a MAT-2 strain using a cosmid library from a MAT-1 strain and screening for a homothallic transformant. The cosmid recovered from this transformant was able to re-transform a MAT-2 strain to homothallism and MAT identity was proven by restriction fragment length polymorphism and conventional genetic mapping. All homothallic transformants could mate with either MAT-1 or MAT-2 strains, although the number of ascospores produced by self matings or crosses to MAT-2 strains was low. Progeny of selfed homothallic transformants were themselves homothallic. MAT-2 was cloned by probing a cosmid library from a MAT-2 strain with a fragment of insert DNA from a MAT-1 cosmid. A 1.5 kb subclone of either MAT-containing cosmid was sufficient to confer mating function in transformants. Examination of the DNA sequence of these subclones revealed that MAT-1 and MAT-2 contain 1297 bp and 1171 bp, respectively, of completely dissimilar DNA flanked by DNA common to both mating types. Putative introns were found (one in each MAT gene) which, when spliced out, would yield open reading frames (ORFs) that occupied approximately 90% of the dissimilar DNA sequences. Translation of the MAT-1 ORF revealed similarity to the Neurospora crassa MATA, Podospora anserina mat-, and Saccharomyces cerevisiae MAT alpha 1 proteins; translation of the MAT-2 ORF revealed similarity to the N. crassa MATa, P. anserina mat+, and Schizosaccharomyces pombe mat-Mc proteins. These gene products are all proven or proposed DNA binding proteins. Those with similarity to MAT-2 are members of the high mobility group.

Non-nucleoside inhibitors of HIV-1 reverse transcriptase: molecular modeling and X-ray structure investigations

The structural features of a new class of non-nucleoside HIV-1 reverse transcriptase inhibitors (3) are presented. Comparison of the structural and electronic properties with those of TIBO (1) and Nevirapine (2) yields a common three-dimensional model. This model permits the improvement of the lead compound 3 by chemical modification (5,6). Additionally, two new types of inhibitors (4, 7) with similar biological activity can be derived from this model. The structure of the new compounds, including their absolute configuration, are determined by X-ray crystallography.

The amino acid sequence of a type I copper protein with an unusual serine- and hydroxyproline-rich C-terminal domain isolated from cucumber peelings

We have determined the amino acid sequence of a small copper protein isolated from cucumber peelings. This cupredoxin contains 137 amino acids including a pyroglutamate as the first residue. The N-terminal 110 amino acid-long domain shows 30-37% identity to 2 other cupredoxins, stellacyanin and cucumber basic blue protein. A unique feature of this protein is a 27 amino acid-long C-terminal domain rich in 4-hydroxyproline and serine and resembling certain plant cell wall proteins. The prolines in this domain are hydroxylated to a different extent depending on the surrounding sequence.