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STUDIES OF A RESTRICTION AND MODIFICATION SYSTEM INDUCED BY PBCV-1 VIRUS INFECTION OF A CHLORELLA-LIKE GREEN ALGA (ENDONUCLEASE, DNA METHYLTRANSFERASE)
Abstract
This dissertation describes two enzymes, a type II restriction endonuclease and a de novo type DNA methyltransferase, which appear in an eukaryotic, Chlorella-like green alga after infection with the virus PBCV-1. The two enzymes share the same substrate specificities and recognize the same target DNA sequence GATC. The restriction endonuclease cleaves GATC sequences 5' to the G and its activity is inhibited by methylation of deoxyadenosine in the GATC sequence. This explains the finding that in vitro the enzyme cleaves host DNA, which contains GATC sequences, but not PBCV-1 DNA, which contains G('m)ATC sequences. The DNA methyltransferase methylates deoxyadenosine solely in GATC sequences. Host DNA, but not PBCV-1 DNA, serves as a good substrate for the DNA methyltransferase in vitro. PBCV-1 DNA is probably methylated by the DNA methyltransferase in vivo and thus protected against cleavage by the restriction endonuclease. Both enzyme activities are first detected between 30 and 60 min after viral infection; the enzymes are synthesized de novo after PBCV-1 infection and are probably virus encoded. Appearance of the two enzyme activities coincides with initiation of host DNA degradation and viral DNA synthesis following PBCV-1 infection. We propose that the PBCV-1 induced restriction endonuclease and DNA methyltransferase are involved in a viral induced restriction and modification system in PBCV-1 infected Chlorella cells.
Subject Area
Molecular biology
Recommended Citation
XIA, YUANNAN, "STUDIES OF A RESTRICTION AND MODIFICATION SYSTEM INDUCED BY PBCV-1 VIRUS INFECTION OF A CHLORELLA-LIKE GREEN ALGA (ENDONUCLEASE, DNA METHYLTRANSFERASE)" (1985). ETD collection for University of Nebraska-Lincoln. AAI8606973.
https://digitalcommons.unl.edu/dissertations/AAI8606973