Mitochondrial DNA polymerase of Drosophila melanogaster
Drosophila DNA polymerase ..gamma.. has been purified 2500-fold from embryonic mitochondria. The near-homogeneous enzyme has a sedimentation coefficient of 7.6 S, a relative molecular mass of 160,000, and is comprised of two polypeptides of 125,000 and 35,000 daltons. Their results indicate that the enzyme is a heterodimer, and allow assignment of the DNA polymerization function to the larger of the two polypeptides. No DNA primase activity is observed in association with the mitochondrial DNA polymerase. Unlike DNA polymerization by the replicative ..cap alpha.. polymerase, that catalyzed by ..cap alpha.. polymerase is efficient on single-stranded as compared to double-stranded DNA templates, under conditions of primer-template excess and optimal salt concentration. In addition, the mitochondrial enzyme demonstrates a high degree of accuracy in nucleotide incorporation. However, the processivity of DNA synthesis by DNA polymerase ..gamma.., defined as the number of nucleotides polymerized per binding event and measured both by kinetic and physical methods, is only 5-15 nucleotides. Furthermore, the enzyme exhibits a limited ability to replicate beyond sites of stable secondary structure in the DNA template. These catalytic properties may indicate a requirement for other cellular factors to enable the enzyme to function efficiently during lagging DNA strand synthesis in the replication of the mitochondrial genome.
- Research Organization:
- Michigan State Univ., East Lansing
- OSTI ID:
- 6031396
- Report Number(s):
- CONF-870644-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cryptic proofreading 3'. -->. 5' exonuclease is associated with the catalytic subunit of DNA polymerase-. cap alpha. from Drosophila melanogaster
Structural and mechanistic investigations into a DNA polymerase from Drosophila melanogaster embryos
Related Subjects
DNA POLYMERASES
CHEMICAL COMPOSITION
FRACTIONATION
DNA
DNA REPLICATION
DROSOPHILA
EMBRYOS
ENZYME ACTIVITY
MITOCHONDRIA
NUCLEOTIDES
ANIMALS
ARTHROPODS
CELL CONSTITUENTS
DIPTERA
ENZYMES
FLIES
FRUIT FLIES
INSECTS
INVERTEBRATES
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
NUCLEOTIDYLTRANSFERASES
ORGANIC COMPOUNDS
ORGANOIDS
PHOSPHORUS-GROUP TRANSFERASES
POLYMERASES
SEPARATION PROCESSES
TRANSFERASES
550200* - Biochemistry