Cloning, expression, and sequence analysis of diaminopropionate ammonia lyase gene from a nonvirulent Salmonella typhimurium PU011.

BACKGROUND: Seeds ofLathyrus sativus, a legume plant, contain 3-oxalyl and 2,3-dioxalyl DAP (O-DAP), neurotoxins which when consumed causes Neurolathyrism or Osteolathyrism, in humans, affecting nervous system and bone formation respectively. Some microorganisms viz virulent and non-virulentSalmonella typhimurium, Salmonella typhi and Pseudomonad have been shown to detoxifyL-alpha,beta-diaminopropionate (DAP), the immediate precursor of O-DAP. RESULT: The gene coding for diaminopropionate ammonia lyase (DAPAL) which detoxifies DAP was cloned from nonvirulentS. typhimurium PU011 into Escherichia coli DH5alpha and the nucleotides sequenced (1212 bp). Whereas the specific enzyme activity of DAPAL obtained from recombinantE. coli PU018 was 0.346 U/mg, the specific activity of the enzyme from nonvirulentS. typhimurium PU011 was 0.351 U/mg. The DAPAL corresponding to 43 kDa protein was found both in nonvirulentS. typhimurium PU011 andE. coli PU018. The Km value was found to be 0.740 mM and 0.680 mM forS. typhimurium PU011 and 0.741 mM and 0.683 mM forE. coli PU018 when grown in minimal medium (MM+DAP) andL. sativus seed extracts respectively, indicating that both of them were capable of utilizing the neurotoxins present inL. sativus seeds. The biomass, enzyme production and the effect of pH and temperature on DAPAL enzyme activity from both non-virulentS. typhimurium PU011 andE. coli PU018 were found to be similar. CONCLUSION: The recombinantE. coli PU018 as well as non-virulentS. typhimurium PU011 are as good as pathogenicS. typhimurium in detoxifying DAP, the immediate precursor of O-DAP present inL. sativus seeds.

Synthesis, characterization and in vitro biological activity studies of Cu-M (M = Cu2+, Co2+, Ni2+, Mn2+, Zn2+) bimetallic complexes.

Six new bimetallic complexes of the type CuCu, CuCo, CuNi, CuZn and CuMn were prepared. The structures of these complexes and the ligand have been proposed on the basis of FAB mass, elemental analysis, UV-vis, IR, EPR and CV studies. All the complexes completely cleave pBS (SK-) DNA at a concentration of 10 microM; however, even at lower concentrations of 2 microM and 0.1 microM, the complexes (I and Ia) showed partial cleavage. The results of the fluorescence binding studies of the metal complexes with CT-DNA showed that the presence of aliphatic ligands added additional binding effects including electrostatic, hydrogen binding and vander Waals interactions. Complexes (I, Ia) showed 50% inhibition of COX-1 and COX-2 activities at as low a concentration as 12.5 microM, 13.5 microM, 14 microM and 14.5 microM. Inhibition assay of top I and top II by different complexes in mutant yeast strains (JN394, JN394 t(-1) and JN394 t(2-5)) with all the complexes showed significant inhibition of topoisomerase at 5 microM concentration. Complexes I and Ia exhibited good anti-microbial activities against all human pathogens tested except Klebsiella pneumoniae. The following studies showed that among the synthesized bimetallic complexes, complexes I and Ia seem to be promising candidates possessing DNA cleavage activities besides anti-microbial and anti-inflammatory properties to serve as chemical nucleases and chemotherapeutic agents.

Production of diamino propionic acid ammonia lyase by a new strain of Salmonella typhimurium PU011.

BACKGROUND: Seeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP). DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP. RESULTS: S. typhimurium PU011, a non-virulent bacterial strain isolated in our lab, was found to produce DAP ammonia lyase enzyme when grown in minimal medium containing DAP. There was a direct correlation between biomass yield and enzyme activity, until 16 h post inoculation in minimal medium containing DAP. Following ammonium sulphate precipitation and passing through Sephadex G100, CM-Sephadex and DEAE-Sephacel for crude enzyme extract preparation, about 68-fold enzyme purity was obtained. The purified enzyme gave maximum activity at pH 8.0 and was stable up to 45 degrees C. The Km value for the substrate was found to be 0.685 mM, calculated from a Line Weaver Burk plot. CONCLUSION: A new bacterial strain, S.typhimurium PU 011, which is capable of producing DAP ammonia lyase, was isolated.

Inhibitory effects of bioactive leads isolated from Pseudomonas aeruginosa PS3 and Pseudomonas fluorescens PS7 on MAP kinases and down regulation of pro inflammatory cytokines (TNF-α, IL-1ß) and mediators (NO, iNOS and COX).

Pure lead molecules, showing anti-inflammatory effect were isolated from the marine Pseudomonas aeruginosa PS3 (GenBank Accession No. EF488968) and Pseudomonas fluorescens PS7 (GenBank Accession No. EF488969) using solvent extraction procedures, subsequent column fractionation, followed by bio activity based screening. The structures of the lead molecules (3S, 8aS)-3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione (Compound 1) and (8aS)-3-(4-hydroxybenyl) hexahydropyrrolo[1,2-a]pyrazine-1,4-dione (Compound 2) obtained from P. aeruginosa PS3 and P. fluorescens PS7 respectively were established employing spectral analysis. Compounds 1 and 2 at their IC(50) values of 84 and 53µM concentrations respectively down regulated expression of tumor necrosis factor-α (TNF-α) and interleukin 1-ß (IL-1ß) in peripheral blood mononuclear cells (PBMCs) and inducible nitric oxide synthase (iNOS) gene in RAW 264.7 cells. Immunoblot analysis revealed the inhibitory effect of pure compounds on phosphorylation of all the three mitogen activated protein kinases (MAPK) such as ERK, JNK and p38 MAPK. The results of the present investigation revealed that the pure compounds are anti-inflammatory in nature.

2,2'-bipyridyl based copper complexes down regulate expression of pro-inflammatory cytokines and suppress MAPKs in mitogen induced Peripheral blood mononuclear cells.

2,2'-bipyridyl based copper complex I: [CuC24H22N6O10] at 10 nM and complex Ia: [Cu2C32H43N8O3](PF6)4 at 7 nM exhibited 50% inhibition of lymphocyte proliferation and less than 20% cytotoxicity in peripheral blood mononuclear cells (PBMCs). Further, pro-inflammatory cytokines such as TNF-alpha and IL-1beta and pro-inflammatory mediator such as Nitric Oxide (NO) besides inducible Nitric Oxide Synthase (iNOS) were inhibited by the copper complexes. They also down regulated the expression of cyclooxegenase-2 (COX-2), yet another mediator of inflammation. Immunoblot analysis revealed the inhibitory effect of these complexes on phosphorylated forms protein kinases (MAPKs) such as ERK1/2, JNK, and p38 in mitogen induced PBMCs.