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Mitochondrial DNA polymerases from yeast to man: a new family of polymerases
N Lecrenier1, P Van Der Bruggen, F Foury
1Laboratoire de Biochimie Physiologique, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
Abstract:
We report the sequence of a 4.5-kb cDNA clone isolated from a human melanoma library which bears high amino acid sequence identity to the yeast mitochondrial (mt) DNA polymerase (Mip1p). This cDNA contains a 3720-bp open reading frame encoding a predicted 140-kDa polypeptide that is 43% identical to Mip1p. The N-terminal part of the sequence contains a 13 glutamine stretch encoded by a CAG trinucleotide repeat which is not found in the other DNA polymerases gamma (Pol gamma). Multiple amino acid sequence alignments with Pol gamma from Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pichia pastoris, Drosophila melanogaster, Xenopus laevis and Mus musculus show that these DNA polymerases form a family strongly conserved from yeast to man and are only loosely related to the Family A DNA polymerases.
Insights
Researchers identified a human melanoma cDNA clone with high sequence identity to yeast mitochondrial DNA polymerase (Mip1p). This discovery highlights a conserved family of DNA polymerases from yeast to humans.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Mitochondrial DNA (mtDNA) polymerase is crucial for mtDNA replication and maintenance.
- Conserved DNA polymerases across species suggest fundamental biological roles.
Purpose of the Study:
- To identify and characterize human homologs of yeast mitochondrial DNA polymerase.
- To investigate the evolutionary conservation of DNA polymerases.
Main Methods:
- Isolation and sequencing of a human melanoma cDNA library.
- Bioinformatic analysis including amino acid sequence alignment.
- Comparison with known DNA polymerases from various species.
Main Results:
- A 4.5-kb cDNA clone was isolated, encoding a 140-kDa polypeptide with 43% identity to yeast Mip1p.
- The human sequence contains a unique N-terminal 13-glutamine stretch not found in other Pol gamma.
- Sequence alignments reveal a conserved family of DNA polymerases from yeast to humans, distinct from Family A polymerases.
Conclusions:
- The identified human cDNA represents a novel DNA polymerase gamma (Pol gamma) with significant homology to its yeast counterpart.
- This finding underscores the evolutionary conservation of Pol gamma family members across eukaryotes.
- The unique glutamine repeat may indicate specialized functions in human mtDNA replication or repair.