Cryptic proofreading 3'. -->. 5' exonuclease is associated with the catalytic subunit of DNA polymerase-. cap alpha. from Drosophila melanogaster

Conference · Fri May 01 00:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6076354

Reyland, M E; Cotterill, S M

Purified DNA polymerase-..cap alpha.., the major replicative polymerase in eucaryotic cells, lacks an associated 3' ..-->.. 5' exonuclease activity. In procaryotes, exonucleolytic proofreading enhances the accuracy of DNA synthesis by 30- to 100-fold. They confirmed that the DNA polymerase-..cap alpha.. from Drosophila lacks detectable exonuclease activity. However, a 3' ..-->.. 5' exonuclease can be detected after separating the 182,000 MW catalytic subunit from other subunits of the enzyme by glycerol gradient sedimentation in the presence of 50% ethylene glycol. The exonuclease activity co-sediments with the 182 kD polymerase subunit, suggesting that both activities reside in the same polypeptide. The 3' ..-->.. 5' exonuclease excises mismatched bases at the 3' termini of double-stranded DNA templates. Excision of a complementary nucleotide at the 3' terminus occurs at a 10-fold lower frequency. When assayed using the Phi X fidelity assay, the error rate of the isolated catalytic subunit is 10/sup -7/; 100 times more accurate than the complex prior to disassociating or a complex of the 182 kD + 73 kD subunits. This parallelism between activation of the 3' ..-->.. 5' exonuclease and increased fidelity suggests that this exonuclease increases accuracy as it does with procaryotic polymerases.

• Research Organization: Univ. of Washington, Seattle
• OSTI ID: 6076354
• 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

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
DNA POLYMERASES
ENZYME ACTIVITY
STRUCTURE-ACTIVITY RELATIONSHIPS
NUCLEASES
DNA REPLICATION
DROSOPHILA
ANIMALS
ARTHROPODS
DIPTERA
ENZYMES
ESTERASES
FLIES
FRUIT FLIES
HYDROLASES
INSECTS
INVERTEBRATES
NUCLEIC ACID REPLICATION
NUCLEOTIDYLTRANSFERASES
PHOSPHODIESTERASES
PHOSPHORUS-GROUP TRANSFERASES
POLYMERASES
TRANSFERASES
550200* - Biochemistry