Genome Sequences of Mycobacterium smegmatis Phages Purgamenstris and PhancyPhin.

Two novel mycobacteriophages, PhancyPhin and Purgamenstris, were isolated from the Houston, Texas, area. They were isolated in the same year with the soil enrichment method using the host Mycobacterium smegmatis mc2 155. They exhibit a 99.55% nucleotide identity with each other.

Indolyl-α-keto-1,3,4-oxadiazoles: Synthesis, anti-cell proliferation activity, and inhibition of tubulin polymerization.

A series of novel indolyl-α-keto-1,3,4-oxadiazole derivatives have been synthesized by employing molecular iodine-mediated oxidative cyclization of acylhydrazones. In vitro anti cell proliferation activity of these derivatives against various cancer cells lines such as human lymphoblast (U937), leukemia (Jurkat & SB) and human breast (BT474) was investigated. Among the synthesized indolyl-α-keto-1,3,4-oxadiazoles 19a-p, only one compound (19e) exhibited significant antiproliferative activity against a panel of cell lines. The compound 19e with 3,4,5-trimethoxyphenyl motif, endowed strong cytotoxicity against U937, Jurkat, BT474 and SB cancer cells with IC50 values of 7.1, 3.1, 4.1, and 0.8 µM, respectively. Molecular docking studies suggested a potential binding mode for 19e in the colchicine binding site of tubulin. When tested for in vitro tubulin polymerizaton, 19e inhibited tubulin polymezations (IC50 = 10.66 µM) and induced apoptosis through caspase 3/7 activation. Further, the derivative 19e did not cause necrosis when measured using lactate dehydrogenase assay.

Synthesis and bioevaluation of 6-chloropyridazin-3-yl hydrazones and 6-chloro-3-substituted-[1,2,4]triazolo[4,3-b]pyridazines as cytotoxic agents.

An efficient synthesis of a series of 6-chloro-3-substituted-[1,2,4]triazolo[4,3-b]pyridazines is described via intramolecular oxidative cyclization of various 6-chloropyridazin-3-yl hydrazones with iodobenzene diacetate. The structures of the newly synthesized compounds were assigned on the basis of elemental analysis, IR, NMR (1H and 13C) and mass spectral data. All the thirty three compounds 3a-q and 4b-q synthesized in the present study were evaluated for their in vitro cytotoxic activities against two Acute Lymphoblastic Leukemia (ALL) cell lines named, SB-ALL and NALM-6, and a human breast adenocarcinoma cell lines (MCF-7). The results revealed that triazoles 4 exhibit better cytotoxicity than their hydrazone precursors 3. Among triazoles, compounds 4f, 4j and 4q exhibited potent cytotoxic activity against SB-ALL and NALM-6 with IC50 values in the range of ∼1.64-5.66 µM and ∼1.14-3.7 µM, respectively, compared with doxorubicin (IC50 = 0.167 µM, SB-ALL). Compounds 4f, 4j and 4q were subjected to apoptosis assay after 48 h treatment and these compounds induced apoptosis of NALM-6 cells via caspase 3/7 activation. Results revealed that compound 4q represents potential promising lead.

Genome Sequences of Subcluster K5 Mycobacteriophages AlleyCat, Edugator, and Guillsminger.

Bacteriophages AlleyCat, Edugator, and Guillsminger were isolated on Mycobacterium smegmatis mc2155 from enriched soil samples. All are members of mycobacteriophage subcluster K5, with genomes of 62,112 to 63,344 bp. Each genome contains 92 to 99 predicted protein-coding genes and one tRNA. Guillsminger is the first mycobacteriophage to carry an IS1380 family transposon.

Genome Sequences of Mycobacteriophages Findley, Hurricane, and TBond007.

We report here the genome sequences of three newly isolated phages that infect Mycobacterium smegmatis mc2155. Phages Findley, Hurricane, and TBond007 were discovered in geographically distinct locations and are related to cluster K mycobacteriophages, with Findley being similar to subcluster K2 phages and Hurricane and TBond007 being similar to subcluster K3 phages.

Genome Sequences of Mycobacteriophages Kerberos, Pomar16, and StarStuff.

We describe the genome sequences of three closely related mycobacteriophages, Kerberos, Pomar16, and StarStuff, isolated at similar times but from geographically distinct regions. All three genomes are similar to those of other subcluster A2 phages, such as L5 and D29, are temperate, and have siphoviral virion morphologies.

Design and synthesis of bis(indolyl)ketohydrazide-hydrazones: Identification of potent and selective novel tubulin inhibitors.

A novel series of ketohydrazide-hydrazones as analogues of naturally occurring coscinamides has been synthesized and evaluated for their anticancer activity against five cancer cell lines. Of the twenty-synthesized ketohydrazide-hydrazones, compounds, 21c, 21f, 21g, 21k and 21o showed cytotoxic effects (less than 50% cell survival) against multiple cancer cell lines when tested at a final concentration of 10 µM. IC50 of three compounds 21f, 21k and 21o was determined to be less than 5 µM for all tested cancer cell lines. Compound 21k exhibited significant anticancer activity against MCF-7, MDA-MB-231, HCT-116 and JURKAT cancer cell lines with IC50 values of 0.8 µM, 0.50 µM, 0.15 µM, and 0.22 µM, respectively. Also, 21k was found to be more selectively cytotoxic against tumor cells when compared to normal cells. Preliminary mechanism of action studies indicated that the most active compound 21k induced caspase-dependent apoptosis in cells. 21k arrests cell cycle in G2/M phase by inhibiting of tubulin polymerization (IC50 = 0.6 µM).

Design, synthesis and in vitro cytotoxicity studies of novel ß-carbolinium bromides.

A series of novel ß-carbolinium bromides has been synthesized from easily accessible ß-carbolines and 1-aryl-2-bromoethanones. The newly synthesized compounds were evaluated for their in vitro anticancer activity. Among the synthesized derivatives, compounds 16l, 16o and 16s exhibited potent anticancer activity with IC50 values of <10µM against tested cancer cell lines. The most potent analogue 16l was broadly active against all the tested cancer cell lines (IC50=3.16-7.93µM). In order to test the mechanism of cell death, we exposed castration resistant prostate cancer cell line (C4-2) to compounds 16l and 16s, which resulted in increased levels of cleaved PARP1 and AO/EB staining, indicating that ß-carbolinium salts induce apoptosis in these cells. Additionally, the most potent ß-carbolines 16l and 16s were found to inhibit tubulin polymerization.

Solvent-free synthesis of bacillamide analogues as novel cytotoxic and anti-inflammatory agents.

Synthesis of fourteen analogues of bacillamide, a bioactive tryptamide alkaloid of marine origin, has been accomplished through a highly efficient convergent route. The present solvent-free protocol involves the formation of thiazole ring in the initial step followed by amide coupling between substituted ethyl 2-alkyl/aryl/heteroaryl/amino/aminoarylthiazole-4-carboxylates and tryptamine in presence of 2-hydroxy-4,6-dimethylpyrimidine, a solid phase catalyst to yield N-[2-(1H-indol-3-yl)ethyl]-2-alkyl/aryl/heteroaryl/amino/aminoarylthiazole-4-carboxamides as bacillamide analogues having structural variation at position-2 of thiazole ring. Bacillamide and its analogues were evaluated for their cytotoxic activity against three cancer cell lines (HCT-116, MDA-MD-231 and JURKAT cell lines) using colorimetric cell proliferation assay. Compounds 17a and 17b exhibited potent anti-cell proliferation activity with IC50 values in the range of ∼3.0 µM and ∼0.1-0.6 µM, respectively against these cell lines. Preliminary mechanism of action studies indicates that these compounds initiate caspase dependent apoptosis. Also, compounds 16d, 16f, 17a and 17d exhibited excellent anti-inflammatory activity comparable to well-known NSAID indomethacin and better to bacillamide, when evaluated using carrageenan induced rat hind paw oedema method.

Adenylyl Cyclase 5 Regulation by Gßγ Involves Isoform-Specific Use of Multiple Interaction Sites.

Adenylyl cyclase (AC) converts ATP into cyclic AMP (cAMP), an important second messenger in cell signaling. Heterotrimeric G proteins and other regulators are important for control of AC activity. Depending on the AC isoform, Gßγ subunits can either conditionally stimulate or inhibit cAMP synthesis. We previously showed that the Gαs-ßγ heterotrimer binds to the N terminus (NT) of type 5 AC (AC5). We now show that Gßγ binds to the NT of a wide variety of AC isoforms. We hypothesized that Gßγ/AC5 interactions involving inactive heterotrimer and Gßγ stimulation of AC5 were separable events. Mutations of the Gßγ "hotspot" show that this site is necessary for AC5 stimulation but not for interactions with the first 198 aa of AC5NT, which is a G protein scaffolding site. This contrasts with AC6, where the Gßγ hotspot is required for both interactions with AC6NT and for stimulation of AC6. Additionally, the SIGK hotspot peptide disrupts Gßγ regulation of AC isoforms 1, 2, and 6, but not AC5. Gßγ also binds the C1/C2 catalytic domains of AC5 and AC6. Finally, cellular interactions with full-length AC5 depend on multiple sites on Gßγ. This suggests an isoform-specific mechanism in which bound Gßγ at the AC5NT is ideally situated for spatiotemporal control of AC5. We propose Gßγ regulation of AC involves multiple binding events, and the role of the AC NT for mechanisms of regulation by heterotrimeric G protein subunits is isoform-specific.

N terminus of type 5 adenylyl cyclase scaffolds Gs heterotrimer.

According to accepted doctrine, agonist-bound G protein-coupled receptors catalyze the exchange of GDP for GTP and facilitate the dissociation of Galpha and Gbetagamma, which in turn regulate their respective effectors. More recently, the existence of preformed signaling complexes, which may include receptors, heterotrimeric G proteins, and/or effectors, is gaining acceptance. We show herein the existence of a preformed complex of inactive heterotrimer (Galpha(s) x betagamma) and the effector type 5 adenylyl cyclase (AC5), localized by the N terminus of AC5. GST fusions of AC5 N terminus (5NT) bind to purified G protein subunits (GDP-Galpha(s) and Gbetagamma) with apparent affinities of 270 +/- 21 and 190 +/- 7 nM, respectively. GDP-bound Galpha(s) and Gbetagamma did not compete, but rather facilitated their interaction with 5NT, consistent with the isolation of a ternary complex (5NT, Galpha(s), and Gbetagamma) by gel filtration. The AC5/Gbetagamma interaction was also demonstrated by immunoprecipitation and fluorescence resonance energy transfer (FRET) and the binding site of heterotrimer Galpha(s) x betagamma mapped to amino acids 60 to 129 of 5NT. Deletion of this region in full-length AC5 resulted in significant reduction of FRET between Gbetagamma and AC. 5NT also interacts with the catalytic core of AC, mainly via the C1 domain, to enhance Galpha(s)--and forskolin-stimulated activity of C1/C2 domains. The N terminus also serves to constrain Galpha(i)-mediated inhibition of AC5, which is relieved in the presence of Gbetagamma. These results reveal that 5NT plays a key regulatory role by interacting with the catalytic core and scaffolding inactive heterotrimeric G proteins, forming a preassembled complex that is potentially braced for GPCR activation.

An adenylyl cyclase-mAKAPbeta signaling complex regulates cAMP levels in cardiac myocytes.

Protein kinase A-anchoring proteins (AKAPs) play important roles in the compartmentation of cAMP signaling, anchoring protein kinase A (PKA) to specific cellular organelles and serving as scaffolds that assemble localized signaling cascades. Although AKAPs have been recently shown to bind adenylyl cyclase (AC), the functional significance of this association has not been studied. In cardiac myocytes, the muscle protein kinase A-anchoring protein beta (mAKAPbeta) coordinates cAMP-dependent, calcium, and MAP kinase pathways and is important for cellular hypertrophy. We now show that mAKAPbeta selectively binds type 5 AC in the heart and that mAKAPbeta-associated AC activity is absent in AC5 knock-out hearts. Consistent with its known inhibition by PKA phosphorylation, AC5 is inhibited by association with mAKAPbeta-PKA complexes. AC5 binds to a unique N-terminal site on mAKAP-(245-340), and expression of this peptide disrupts endogenous mAKAPbeta-AC association. Accordingly, disruption of mAKAPbeta-AC5 complexes in neonatal cardiac myocytes results in increased cAMP and hypertrophy in the absence of agonist stimulation. Taken together, these results show that the association of AC5 with the mAKAPbeta complex is required for the regulation of cAMP second messenger controlling cardiac myocyte hypertrophy.

Physiological roles for G protein-regulated adenylyl cyclase isoforms: insights from knockout and overexpression studies.

Cyclic AMP is a universal second messenger, produced by a family of adenylyl cyclase (AC) enzymes. The last three decades have brought a wealth of new information about the regulation of cyclic AMP production by ACs. Nine hormone-sensitive, membrane-bound AC isoforms have been identified in addition to a tenth isoform that lacks membrane spans and more closely resembles the cyanobacterial AC enzymes. New model systems for purifying and characterizing the catalytic domains of AC have led to the crystal structure of these domains and the mapping of numerous interaction sites. However, big hurdles remain in unraveling the roles of individual AC isoforms and their regulation in physiological systems. In this review we explore the latest on AC knockout and overexpression studies to better understand the roles of G protein regulation of ACs in the brain, olfactory bulb, and heart.

Conditional stimulation of type V and VI adenylyl cyclases by G protein betagamma subunits.

In a yeast two-hybrid screen of mouse brain cDNA library, using the N-terminal region of human type V adenylyl cyclase (hACV) as bait, we identified G protein beta2 subunit as an interacting partner. Additional yeast two-hybrid assays showed that the Gbeta(1) subunit also interacts with the N-terminal segments of hACV and human type VI adenylyl cyclase (hACVI). In vitro adenylyl cyclase (AC) activity assays using membranes of Sf9 cells expressing hACV or hACVI showed that Gbetagamma subunits enhance the activity of these enzymes provided either Galpha(s) or forskolin is present. Deletion of residues 77-151, but not 1-76, in the N-terminal region of hACVI obliterated the ability of Gbetagamma subunits to conditionally stimulate the enzyme. Likewise, activities of the recombinant, engineered, soluble forms of ACV and ACVI, which lack the N termini, were not enhanced by Gbetagamma subunits. Transfection of the C terminus of G protein receptor kinase 2 to sequester endogenous Gbetagamma subunits attenuated the ability of isoproterenol to increase cAMP accumulation in COS-7 cells overexpressing hACVI even when G(i) was inactivated by pertussis toxin. Therefore, we conclude that the N termini of human hACV and hACVI are necessary for interactions with, and regulation by, Gbetagamma subunits both in vitro and in intact cells. Moreover, Gbetagamma subunits derived from a source(s) other than G(i) are necessary for the full activation of hACVI by isoproterenol in intact cells.

Purification and characterization of cathepsin L-like proteinase from goat brain.

Cathepsin L-like proteinase was purified approximately 1708-fold with 40% activity yield to an apparent electrophoretic homogeneity from goat brain by homogenization, acid-autolysis at pH 4.2, 30-80% (NH4)2SO4 fractionation, Sephadex G-100 column chromatography and ion-exchange chromatography on CM-Sephadex C-50 at pH 5.0 and 5.6. The molecular weight of proteinase was found to be approximately 65,000 Da, by gel-filtration chromatography. The pH optima were 5.9 and 4.5 for the hydrolysis of Z-Phe-Arg-4mbetaNA (benzyloxycarbonyl-L-phenylalanine-L-arginine-4-methoxy-beta-naphthylamide) and azocasein, respectively. Of the synthetic chromogenic substrates tested, Z-Phe-Arg-4mbetaNA was hydrolyzed maximally by the enzyme (Km value for hydrolysis was 0.06 mM), followed by Z-Val-Lys-Lys-Arg-4mbetaNA, Z-Phe-Val-Arg-4mbetaNA, Z-Arg-Arg-4mbetaNA and Z-Ala-Arg-Arg-4mbetaNA. The proteinase was activated maximally by glutathione in conjunction with EDTA, followed by cysteine, dithioerythritol, thioglycolic acid, dithiothreitol and beta-mercaptoethanol. It was strongly inhibited by p-hydroxymercuribenzenesulphonic acid, iodoacetic acid, iodoacetamide and microbial peptide inhibitors, leupeptin and antipain. Leupeptin inhibited the enzyme competitively with Ki value 44 x 10(-9) M. The enzyme was strongly inhibited by 4 M urea. Metal ions, Hg(2+), Ca(2+), Cu(2+), Li(2+), K(+), Cd(2+), Ni(2+), Ba(2+), Mn(2+), Co(2+) and Sn(2+) also inhibited the activity of the enzyme. The enzyme was stable between pH 4.0-6.0 and up to 40 degrees C. The optimum temperature for the hydrolysis of Z-Phe-Arg-4mbetaNA was approximately 50-55 degrees C with an activation energy Ea of approximately 6.34 KCal mole(-1).

Effects of some antituberculous and anti-leprotic drugs on cathepsins B, H and L.

The cysteine proteinases like cathepsins B, L and H are main hydrolytic enzymes present in lysosomes and play an important role in intracellular protein degradation. Tuberculosis and leprosy, both are tissue- destructive diseases. Main drugs used in chemotherapy of these diseases may inhibit the main lysosomal cysteine proteinases i.e. cathepsins B, L and H released during tissue destruction and thus prevent the further destruction of tissue by these enzymes. So the aim of this study is to see the effect of antituberculous and antileprotic drugs on these proteolytic enzymes. The effect of commonly used antituberculous and antileprotic drugs was screened on the activities of purified brain lysosomal cysteine proteinases namely cathepsins B [EC 3.4.22.1], L [EC 3.4.22.15] and H [EC 3.4.22.16]. Among the antileprotic drugs, only clofazimine inhibited the enzymic activities whereas dapsone had no effect whatsoever. In antituberculous drugs, rifampicin was the most inhibitory while isoniazid had little inhibitory potency. Streptomycin and pyrazinamide did not effect the activities at all. As regards the mechanism of inhibition, clofazimine and isoniazid inhibited the enzymes in a non-competitive manner with K values of 0.25 mM and 5.0 mM for cathepsin B, 0.071 mM and 0.833 mM for cathepsin L and 1.513 mM and 0.885 mM for cathepsin H, While rifampicin could effect in a competitive manner with K(i) values of 0.03 mM, 0.125 mM and 0.027 mM for cathepsin B, L and H respectively.