Open AccessStimulation of 3′→5′ Exonuclease and 3′-Phosphodiesterase Activities of Yeast Apn2 by Proliferating Cell Nuclear Antigen
Author(s) -
Ildikó Unk,
Lajos Haracska,
Xavier V. Gomes,
Peter M. Burgers,
Louise Prakash,
Satya Prakash
Publication year - 2002
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.22.18.6480-6486.2002
Subject(s) - proliferating cell nuclear antigen , biology , microbiology and biotechnology , dna replication , dna repair , primer (cosmetics) , exonuclease , dna , processivity , endonuclease , dna polymerase delta , ap site , biochemistry , dna polymerase , chemistry , reverse transcriptase , gene , rna , organic chemistry
The Apn2 protein of Saccharomyces cerevisiae contains 3'-->5' exonuclease and 3'-phosphodiesterase activities, and these activities function in the repair of DNA strand breaks that have 3'-damaged termini and which are formed in DNA by the action of oxygen-free radicals. Apn2 also has an AP endonuclease activity and functions in the removal of abasic sites from DNA. Here, we provide evidence for the physical and functional interaction of Apn2 with proliferating cell nuclear antigen (PCNA). As indicated by gel filtration and two-hybrid studies, Apn2 interacts with PCNA both in vitro and in vivo and mutations in the consensus PCNA-binding motif of Apn2 abolish this interaction. Importantly, PCNA stimulates the 3'-->5' exonuclease and 3'-phosphodiesterase activities of Apn2. We have examined the involvement of the interdomain connector loop (IDCL) and of the carboxy-terminal domain of PCNA in Apn2 binding and found that Apn2 binds PCNA via distinct domains dependent upon whether the binding is in the absence or presence of DNA. In the absence of DNA, Apn2 binds PCNA through its IDCL domain, whereas in the presence of DNA, when PCNA has been loaded onto the template-primer junction by replication factor C, the C-terminal domain of PCNA mediates the binding.