Identifying Thermostability Characteristics of Family A DNA Polymerases

DNA polymerases create complimentary DNA strand in living cells and are crucial to genome transmissionand maintenance. All of these enzymes possess similar human right-handed fold which contain of thumb,fingers and palm subdomains and contribute to polymerization activities. These enzymes classified to ۷evolutionary families A, B, C, D, X, Y and RT based on amino acid sequences analysis and biochemicalcharacteristics. Family A DNA polymerases exist on extended range of organisms included mesophilic,thermophilic and hyper thermophilic bacteria, participate in DNA replication and repair and have broadapplication in molecular biology and biotechnology. In this study, we attempt to detect factors play a role inthermostability properties of this family member despite their remarkable similarities in structure andfunction. For this purpose, similarities and differences in amino acid sequences, structure and dynamics ofthese enzymes have inspected. Our results demonstrated that thermophilic and hyper thermophilic enzymeshave more charged, aromatic and polar residues than mesophilic ones, and consequently show furtherelectrostatic and cation-pi interactions. In addition, in thermophilic enzymes, Tryptophan, Histidine andaliphatic residues tend to position in buried states more than mesophilic enzymes. These residues within theiraliphatic parts increase hydrophobic core packing and therefore enhance thermostability of these enzymes.Moreover, molecular dynamic simulation results reveal that increasing of temperature impact mesophilicenzymes further than thermophilic ones, showing as rise in structural fluctuations and flexibilities.

کلیدواژه ها:

Family A DNA Polymerases ، Thermostability ، Thermophilic Enzymes ، Molecular Dynamic Simulations