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Now showing items 1 - 5 of 5

  • Evolutionary history of the neuropeptide S receptor/neuropeptide S system

    Ravisankar Valsalan   Narayanan Manoj  

    Highlights • The present review describes the molecular evolution of the NPSR–NPS system. • Ancestral NPSR and NPS genes first arose in an ancestral bilaterian. • NPSR–NPS system has been shaped by gene losses. • NPSR–NPS system is an example of long-term coevolution in a receptor–peptide pair. Abstract The neuropeptide S receptor (NPSR) belongs to the G protein-coupled receptor (GPCR) superfamily and is activated by the neuropeptide S (NPS). Although recently discovered, the vertebrate NPSR–NPS system has been established as an important signaling system in the central nervous system and is involved in physiological processes such as locomotor activity, wakefulness, asthma pathogenesis, anxiety and food intake. The availability of a large number of genome sequences from multiple bilaterian lineages has provided an opportunity to establish the evolutionary history of the system. This review describes the origin and the molecular evolution of the NPSR–NPS system using data derived primarily from comparative genomic analyses. These analyses indicate that the NPSR–NPS system and the vasopressin-like receptor–vasopressin/oxytocin peptide (VPR–VP/OT) system originated from a single system in an ancestral bilaterian. Multiple duplications of this ancestral system gave rise to the bilaterian VPR–VP/OT system and to the protostomian cardioacceleratory peptide receptor–cardioacceleratory peptide (CCAPR–CCAP) system and to the NPSR–NPS system in the deuterostomes. Gene structure features of the receptors were consistent with the orthology annotations derived from phylogenetic analyses. The orthology of the peptide precursors closely paralleled that of the receptors suggesting an ancient coevolution of the receptor–peptide pair. An important challenge for the coevolution hypothesis will be to establish the molecular and structural basis of the divergence between orthologous receptor–ligand pairs in this system.
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  • Structure of Human Phosphopantothenoylcysteine Synthetase at 2.3 ? Resolution

    Narayanan Manoj   Erick Strauss   Tadhg P Begley   Steven E Ealick  

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  • A temperature-responsive gene in sorghum encodes a glycine-rich protein that interacts with calmodulin

    Supreet Singh   Amardeep Singh Virdi   Rajdeep Jaswal   Mrinalini Chawla   Sanjay Kapoor   Samar B. Mohapatra   Narayanan Manoj   Ashwani Pareek   Sanjay Kumar   Prabhjeet Singh  

    Abstract Imposition of different biotic and abiotic stress conditions results in an increase in intracellular levels of Ca 2+ which is sensed by various sensor proteins. Calmodulin (CaM) is one of the best studied transducers of Ca 2+ signals. CaM undergoes conformational changes upon binding to Ca 2+ and interacts with different types of proteins, thereby, regulating their activities. The present study reports the cloning and characterization of a sorghum cDNA encoding a protein (SbGRBP) that shows homology to glycine-rich RNA-binding proteins. The expression of SbGRBP in the sorghum seedlings is modulated by heat stress. The SbGRBP protein is localized in the nucleus as well as in cytosol, and shows interaction with CaM that requires the presence of Ca 2+ . SbGRBP depicts binding to single- and also double-stranded DNA. Fluorescence spectroscopic analyses suggest that interaction of SbGRBP with nucleic acids may be modulated after binding with CaM. To our knowledge, this is the first study to provide evidence for interaction of a stress regulated glycine-rich RNA-binding protein with CaM. Highlights • cDNA encoding a Sorghum glycine-rich RNA-binding protein (SbGRBP) has been cloned. • SbGRBP shows interaction with CaM, which is Ca 2+ -dependent. • First study to demonstrate interaction of CaM with a protein of GRBP family. • SbGRBP also shows binding with single- and double stranded DNA. • Interaction of SbGRBP with DNA appears to be modulated by CaM.
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  • Crystal structure of Thermotoga maritima acetyl esterase complex with a substrate analog: Insights into the distinctive substrate specificity in the CE7 carbohydrate esterase family

    Mrityunjay K. Singh   Narayanan Manoj  

    Abstract The carbohydrate esterase family 7 (CE7) members are acetyl esterases that possess unusual substrate specificity for cephalosporin C and 7-amino-cephalosporanic acid. This family containing the α/β hydrolase fold has a distinctive substrate profile that allows it to carry out hydrolysis of esters containing diverse alcohol moieties while maintaining narrow specificity for an acetate ester. Here we investigate the structural basis of this preference for small acyl groups using the crystal structure of the thermostable Thermotoga maritima CE7 acetyl esterase (TmAcE) complexed with a non-cognate substrate analog. The structure determined at 1.86 Å resolution provides direct evidence for the location of the largely hydrophobic and rigid substrate binding pocket in this family. Furthermore, a three-helix insertion domain near the catalytic machinery shapes the substrate binding site. The structure reveals two residues (Pro228 and Ile276) which constitute a hydrophobic rigid binding surface for the acyl group of the ester and thus restricts the size of the acyl group that be accommodated. In combination with previous literature on kinetic properties of the enzyme, our studies suggest that these residues determine the unique specificity of the TmAcE for short straight chain esters. The structure provides a template for focused attempts to engineer the CE7 enzymes for enhanced stability, selectivity or activity for biocatalytic applications. Highlights • Crystal structure of TmAcE in complex with a substrate analog is determined. • The active site cavity is largely hydrophobic and rigid. • A residue from a three-helix insertion domain is important for catalytic function. • Two residues mediate the unique substrate specificity for short chain esters of diverse alcohols.
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  • Multi Polarization Antenna Structures for Efficient MIMO Systems Employing Software Radio Design Methodology

    Narayanan Manoj   Amir Faizal   Smruti Santosh Palai  

    This paper presents the different States of Polarizations (SOPs) of the transmitting and receiving antennas that can be used for improving the efficiency of a MIMO system. The analysis is performed for a 3 in 3 out MIMO platform. A method for generating these SOPs is presented. Some simulation reports are provided for validating the concepts presented. One particular SOP which requires a 4.4 dB relative attenuation and a phase difference of 90 degrees between the linear vertical polarization (LVP) and linear horizontal polarization (LHP) feeds. The phase difference obtained has a deviation of approximately 1 degree with respect to the desired design specification of 90 degrees. This may be eliminated by employing alternate designs for the discrete phase shifter which gives higher resolution accuracy. The paper concludes with suggestions for future work.
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