Alajmi, M. F. | Search bioRxiv

bioRxiv2022

Biological evaluation of novel side chain containing CQTrICh-analogs as antimalarials and their development as PfCDPK1 kinase inhibitors

To combat the emergence of drug resistance against the existing antimalarials, novel side chain containing 7-chloroquinoline-indole-chalcones tethered with a triazole (CQTrICh-analogs 7 (a-s) and 9) were designed and synthesized by reacting substituted 1-phenyl-3-(1-(prop-2-yn-1- yl)-1H-indol-3-yl) prop-2-en-1-one and 1-(prop-2-yn-1-yl)-1H-indole-3-carbaldehyde with 4- azido-7-chloroquinoline, respectively via a click reaction. The selected CQTrICh-analogs: 7l and 7r inhibited chloroquine-sensitive (3D7) and resistant (RKL-9) strains of Plasmodium falciparum, with IC50 values of 2.4 {micro}M & 1.8 {micro}M (7l), and 3.5 {micro}M & 2.7 {micro}M (7r), respectively, and showed insignificant hemolysis and cytotoxicity in mammalian cells. Intra-erythrocytic progression studies revealed that the active hybrids: 7l and 7r are effective against the mature stages of the parasite. Given the importance of Calcium-Dependent Protein Kinase 1 (PfCDPK1) in the parasite biology, notably during late schizogony and subsequent invasion of merozoites into host RBCs, we identified this protein as a possible molecular target of these active hybrids. In silico interaction analysis indicated that 7l and 7r stably interact with the catalytically active ATP-binding pocket of PfCDPK1, by the formation of energetically favorable H-bonds. Furthermore, in vitro Microscale Thermophoresis and kinase assays with recombinant PfCDPK1 demonstrated that the active hybrids interact with and inhibit the kinase activity, thus presumably responsible for the parasite growth inhibition. Interestingly, 7l and 7r showed no inhibitory effect on the human kinases, indicating that they are selective for the parasite kinase. Conceivably, we report the antiplasmodial potential of novel kinase targeting bio-conjugates, a step towards developing pan-kinase inhibitors, which is a prerequisite for cross-stage anti-malarial protection. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/498981v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@113574borg.highwire.dtl.DTLVardef@c81a33org.highwire.dtl.DTLVardef@1301d22org.highwire.dtl.DTLVardef@1c8cac5_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2018

Structural and functional impact of non- synonymous SNPs in the CST complex subunit TEN1: Structural genomics approach

TEN1 protein is a key component of CST complex, implicated in maintaining the telomere homeostasis, and provide stability to the eukaryotic genome. Mutations in TEN1 gene have higher chances of deleterious impact; thus, interpreting the number of mutations and their consequential impact on the structure, stability and function is essentially important. Here, we have investigated the structural and functional consequences of nsSNPs in the TEN1 gene. A wide array of sequence- and structure-based computational prediction tools were employed to identify the effects of 78 nsSNPs on the structure and function of TEN1 protein and deleterious nsSNPs were identified. These deleterious or destabilizing nsSNPs are scattered throughout the structure of TEN1. However, major mutations were observed in the 1-helix (12-16) and {beta}5-strand (88-96). We further observed that mutations at C-terminal region were have higher tendency to form aggregate. In-depth structural analysis of these mutations reveals that the pathogenecity of these mutations are driven mainly through larger structural changes because of alterations in non-covalent interactions. This work provides a blue print to pinpoint the possible consequences of pathogenic mutations in the CST complex subunit TEN1.

evolutionary biology↗