DNA Polymerase in Thermococcus gorgonarius

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Function

DNA polymerase has an important role in the development of life. DNA polymerase is an enzyme, which synthesizes new stands of DNA from preexisting DNA. It does this by adding one nucleotide at a time to the 3’ end of a growing strand. The new DNA strands are always synthesized from 5’ to the 3’ direction. (GENETICS BOOK) The original DNA stands are used as templates for the synthesis of new strands of DNA. DNA polymerases are the enzymes that catalyze the attachment of nucleotides to synthesize a new DNA strand. DNA polymerase I is composed of a single polypeptide that removes the RNA primers and replaces them with DNA. DNA polymerase III is responsible for the majority of the DNA replication and the proofreading from 3’ to 5’. DNA follows Chargaff’s rule, which states that cytosine binds to guanine and adenine binds to thymine. (http://www.slideshare.net/JordiMartin1/chap11-studyppt) Each time a cell divides, DNA polymerase duplicates all of the cell’s DNA, and the cell passes one copy of DNA to each daughter cell. DNA polymerase roughly makes only one mistake every billion bases. Although Chargaff’s rule help makes the replication on DNA polymerase easier, an extra step of proofreading and cutting out the mismatched bases after replication is the reason why DNA polymerase is the most accurate enzyme. (http://www.rcsb.org/pdb/101/motm.do?momID=3)

Disease

http://tools.niehs.nih.gov/polg/

Relevance

Structural highlights

DNA polymerase is composed of 1,005 nucleotides. The polypeptide is compiled of 335 residues, once it is translated. DNA polymerase contain nineteen α-helices and eight β-sheets. ^[3] The structure of DNA polymerase can be described by using the “right hand model” which has a “palm”, “fingers”, and “thumb” regions. The palm region catalyzes the phosphoric transfer. The finger region interacts with the incoming nucleotides and the template base they are paired with and the thumb helps in positioning the DNA and in translocation.(http://www.worthington-biochem.com/DNAECI/default.html)

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