Department of Biological Sciences

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Author: search.filters.author.Chowdhury, ShibasishSubject: search.filters.subject.AP endonuclease

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    In Silico Analysis of the Endonuclease III Protein Family Identifies Key Residues and Processes During Evolution
    (Springer, 2015-07-07) Chowdhury, Shibasish; Mehrotra, Rajesh
    DNA repair refers to a collection of processes by which a cell identifies and corrects damage to genomic DNA molecules. DNA repair processes significantly overcome DNA damage and restore the normal nucleotide sequence and DNA structure. This study focuses on the evolution of the endonuclease III gene/protein family, which plays a key role in the base excision repair pathway. We analyzed 463 homologs of the endonuclease III protein and compared them with the corresponding gene and 16S/18S rRNA sequences to understand the evolutionary processes of this protein family. The sequence analysis and comparison reveal consensus sequence motifs within the ENDO3c and iron–sulfur cluster loop domains that are functionally and structurally important. On the basis of phylogenetic analysis, we propose an evolutionary model of the endonuclease III protein family. Horizontal gene transfer was identified as the key event among bacteria, archaea, and eukaryotic organisms that occurred during the evolution of the endonuclease III gene family among bacteria, archaea, and eukaryotic organisms. This analysis may be exploited to achieve a better prediction of the endonuclease III family gene/protein in unannotated organisms or families of organisms that are completely sequenced as well as in those for which sequencing is ongoing.
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    Evolution of endonuclease IV protein family: an in silico analysis
    (Springer, 2019-04-06) Chowdhury, Shibasish
    DNA repair is one of the key cellular events which balances between evolvability and integrity of the genome. Endonuclease IV enzymes are class II AP endonucleases under base excision repair pathway which act on abasic site and break the phosphodiester bond at the 5′ side. The role and activity of endonuclease IV proteins vary among different organisms; even it is absent in higher eukaryotes. The evolution of this protein family was studied by analyzing all homologs of the endonuclease IV protein family through different in silico techniques including phylogenetic tree generation and model building. The sequence analysis revealed four consensus sequence motifs within the AP2EC domain which are functionally important and conserved throughout the evolution process. It was also observed that the species and endonuclease IV gene evolution shape up differently in most of the organisms. Presence of the mitochondria-targeted signal peptides in fungal species Saccharomyces and Coccidioides suggest a possible endosymbiotic transfer of endonuclease IV genes to lower eukaryotes. Evolutionary changes among various clades in the protein-based phylogenetic tree have been investigated by comparison of homology models which suggests the conservation of overall fold of endonuclease IV proteins except for few alterations in loop orientation in few clades.