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Dissecting the Mechanism of Unwinding by Human Mitochondrial DNA Helicase
Author(s) -
Sen Doyel,
Patel Smita
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.880.7
Subject(s) - helicase , mitochondrial dna , biology , dna replication , dna , prokaryotic dna replication , genetics , mechanism (biology) , gene , primase , control of chromosome duplication , microbiology and biotechnology , polymerase chain reaction , rna , reverse transcriptase , philosophy , epistemology
TWINKLE is the only known helicase at the human mitochondrial DNA (HmtDNA) replication fork. It is encoded by PEO1 gene of chromosome 10. It shares 46% amino acid sequence similarity with the helicase T7gene4(gp4) from bacteriophage. Mutations in PEO1 have been linked to deletions in the mitochondrial DNA causing neuromuscular disorders in human. To understand the diseases better, it is crucial to define the molecular mechanism of HmtDNA replication guided by the proteins involved in it. In this study, we have focused on understanding the kinetics of dsDNA unwinding by TWINKLE using ensemble assay with radiolabeled DNA substrates. We have observed that the characteristic unwinding activity of TWINKLE is markedly different from T7gp4. Our most interesting finding indicates that the morphology of non‐translocating strand plays a major role during unwinding by TWINKLE. This is an important step towards understanding the mechanism of initiation of replication from the D‐loop in the mitochondrial DNA. Our final goal is to understand the mechanism of replication of mitochondrial DNA in vitro which in turn would allow us to define the molecular basis of the diseases in human.