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Abstract Background The presence of four mammalian cell entry (mce) operons in Mycobacterium tuberculosis suggests the essentiality of the functions of the genes in these operons. The differential expression of the four mce operons in different phases of in vitro growth and in infected animals reported earlier from our laboratory further justifies the apparent redundancy for these genes in the genome. Here we investigate the extent of polymorphism in eight genes in the mce1 and mce4 operons of M. tuberculosis from four standard reference strains (H37Rv, H37Ra, LVS (Low Virulent Strain) and BCG) and 112 clinical isolates varying in their drug susceptibility profile, analysed by direct sequencing and Sequenom MassARRAY platform. Results We discovered 20 single nucleotide polymorphisms (SNPs) in the two operons. The comparative analysis of the genes of mce1 and mce4 operons revealed that yrbE1A [Rv0167] was most polymorphic in mce1 operon while yrbE4A [Rv3501c] and lprN [Rv3495c] had the highest number of SNPs in the mce4 operon. Of 20 SNPs, 12 were found to be nonsynonymous and were further analysed for their pathological relevance to M. tuberculosis using web servers PolyPhen and PMut, which predicted five deleterious nonsynonymous SNPs. A mutation from proline to serine at position 359 of the native Mce1A protein was most deleterious as predicted by both PolyPhen and PMut servers. Energy minimization of the structure of native Mce1A protein and mutated protein was performed using InsightII. The mutated Mce1A protein showed structural changes that could account for the effects of this mutation. Conclusions Our results show that SNPs in the coding sequences of mce1 and mce4 operons in clinical isolates can be significantly high. Moreover, mce4 operon is significantly more polymorphic than mce1 operon (p < 0.001). However, the frequency of nonsynonymous substitutions is higher in mce1 operon and synonymous substitutions are more in mce4 operon. In silico modeling predict that nonsynonymous SNP at mce1A [Rv0169], a virulence gene could play a pivotal role in causing functional changes in M. tuberculosis that may reflect upon the biology of the bacteria.

A series of trans substituted porphodimethenes carrying varied PAH (polyaromatic hydrocarbon) substituents from phenyl to hexabenzocoronene have been synthesized. Spectroscopic and DFT (Density Functional Theory) studies clearly show that PDMs (Porphodimethenes) exhibit distortion from rooftop structure and approach planarity with increase in size of PAH units. The diacid form H2(PDM).2X− upon addition of several acids to PDMs have been characterized where X denotes Cl−, Br−, CH3SO3−, CF3COO− accompanied by an exceptional chromogenic color change from yellow to dark pink initiating with higher aromatics. The unique conformational changes with distinct color changes were monitored by UV visible, 1H NMR spectroscopy, DFT computations. [ABSTRACT FROM AUTHOR]

Abstract: We have earlier conclusively established the Calreticulin Transacetylase (CRTAase) catalyzed modifications of functional proteins such as cytochrome-P450-linked mixed function oxidases (Cyt-P450-linked MFOs), NADPH cytochrome c reductase, and glutathione S-transferase by acetoxy derivatives of polyphenols. In this study, we have investigated the comparative specificities of CRTAase to N-acetyl derivative, 7-acetamido-4-methylcoumarin (7-N-AMC), O-acetyl derivative, 7-acetoxy-4-methylcoumarin (7-AMC), S-acetyl derivative, 7-thioacetyl-4-methycoumarin (7-S-AMC) and their parent compounds in the modulation of catalytic activities of aforesaid proteins. Special attention concentrated on the comparative inhibitory effect of aforesaid acetyl moiety on Cyt-P450-linked MFOs such as 7-ethoxyresorufin O-deethylase (EROD), pentoxyresorufin O-dealkylase (PROD) and aflatoxin B1 (AFB1)-induced genotoxicity in vitro and in vivo. The results clearly indicated that N-acetyl and O-acetyl derivatives were better substrates for CRTAase while the S-acetyl was found to be a poorer substrate. Our study involving atomic charge, charge density and molecular electrostatic potential (MEP) calculations indicated the pivotal role of electronegativity and charge distribution values of O, N and S atoms of the acetyl group at C-7 position of the 4-methylcoumarins in CRTAase activity. These facts reinforce our hypothesis that the CRTAase catalyzed modifications of the catalytic activities of aforesaid proteins by acetyl derivative of 4-methylcoumarins is probably due to acetylation of these proteins. [Copyright &y& Elsevier]

Peroxisome proliferator-activated receptor gamma (PPAR γ ) is a potential target for the treatment of several disorders. In view of several FDA approved kinase inhibitors, in the current study, we have investigated the interaction of selected kinase inhibitors with PPAR γ using computational modeling, docking, and molecular dynamics simulations (MDS). The docked conformations and MDS studies suggest that the selected KIs interact with PPAR γ in the ligand binding domain (LBD) with high positive predictive values. Hence, we have for the first time shown the plausible binding of KIs in the PPAR γ ligand binding site. The results obtained from these in silico investigations warrant further evaluation of kinase inhibitors as PPAR γ ligands in vitro and in vivo., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this paper.

The potential role of polyphenolic acetate (PA) in causing diverse biological and pharmacological actions has been well studied in our laboratory. Our investigations, for the first time, established the role of calreticulin transacetylase (CRTAase) in catalyzing the acetylation of nitric oxide synthase (NOS) by Pas leading to robust activation of NOS. 7, 8- Diacetoxy-4-methylcoumarin (DAMC) and other acetoxycoumarins augmented the expression of thioredoxin (TRX) and vascular endothelial growth factor (VEGF) in human peripheral blood mononuclear cells (PBMCs). These findings substantiated our earlier observations that DAMC was a superb inducer of angiogenesis. The enhanced expression of thioredoxin reductase (TRXR) and diminished expression of thioredoxin interacting protein (TRXIP) leading to increased expression and activity of TRX in PBMCs due to the action of DAMC was revealed by real time RT-PCR analysis. The possible activation of TRX due to acetylation was confirmed by the fact that TRX activity of PBMCs was enhanced by various acetoxycoumarins in tune with their affinities to CRTAase as substrates. DAMC caused enhanced production of NO by way of acetylation of NOS as mentioned above and thereby acted as an inducer of VEGF. Real time RT-PCR and VEGF ELISA results also revealed the overexpression of TRX. DAMC and other PAs were found to reduce the oxidative stress in cells as proved by significant reduction of intracellular ROS levels. Thus, the crucial role of TRX in DAMC-induced angiogenesis with the involvement of VEGF was established.

The potential role of polyphenolic acetate (PA) in causing diverse biological and pharmacological actions has been well studied in our laboratory. Our investigations, for the first time, established the role of calreticulin transacetylase (CRTAase) in catalyzing the acetylation of nitric oxide synthase (NOS) by Pas leading to robust activation of NOS. 7, 8-Diacetoxy-4-methylcoumarin (DAMC) and other acetoxycoumarins augmented the expression of thioredoxin (TRX) and vascular endothelial growth factor (VEGF) in human peripheral blood mononuclear cells (PBMCs). These findings substantiated our earlier observations that DAMC was a superb inducer of angiogenesis. The enhanced expression of thioredoxin reductase (TRXR) and diminished expression of thioredoxin interacting protein (TRXIP) leading to increased expression and activity of TRX in PBMCs due to the action of DAMC was revealed by real time RT-PCR analysis. The possible activation of TRX due to acetylation was confirmed by the fact that TRX activity of PBMCs was enhanced by variousacetoxycoumarins in tune with their affinities to CRTAase as substrates. DAMC caused enhanced production of NO by way of acetylation of NOS as mentioned above and thereby acted as an inducer of VEGF. Real time RT-PCR and VEGF ELISA results also revealed the overexpression of TRX. DAMC and other PAs were found to reduce the oxidative stress in cells as proved by significant reduction of intracellular ROS levels. Thus, the crucial role of TRX in DAMC-induced angiogenesis with the involvement of VEGF was established.