TY - JOUR
T1 - Effect of CpG methylation on gene expression in transfected plant protoplasts
AU - Hershkovitz, Maty
AU - Gruenbaum, Yosef
AU - Renbaum, Paul
AU - Razin, Aharon
AU - Loyter, Abraham
PY - 1990
Y1 - 1990
N2 - Activity of the cat gene driven by the cauliflower mosaic virus 35S promoter has been assayed by transfecting petunia protoplasts with the pUC8CaMVCAT plasmid. In vitro methylation of this plasmid with M · HpaII (methylates Ċ CĊGG sites) and M · HhaI (methylates GĊGC sites) did not affect bacterial chloramphenicol acetyltransferase (CAT) activity. It should be noted, however, that no HpaII or HhaI sites are present in the promoter sequence. In contrast, in vitro methylation of the plasmid with the spiroplasma methylase M · SssI, which methylates all ĊpG sites, resulted in complete inhibition of CAT activity. The promoter sequence contains 16 CpG sites and 13 CpNpG sites that are known to be methylation sites in plant DNA. In the light of this fact, and considering the results of the experiments presented here, we conclude that methylation at all ĊpG sites leaving CpNpG sites unmethylated is sufficient to block gene activity in a plant cell. Methylation of ĊpNpG sites in plant cells may, therefore, play a role other than gene silencing.
AB - Activity of the cat gene driven by the cauliflower mosaic virus 35S promoter has been assayed by transfecting petunia protoplasts with the pUC8CaMVCAT plasmid. In vitro methylation of this plasmid with M · HpaII (methylates Ċ CĊGG sites) and M · HhaI (methylates GĊGC sites) did not affect bacterial chloramphenicol acetyltransferase (CAT) activity. It should be noted, however, that no HpaII or HhaI sites are present in the promoter sequence. In contrast, in vitro methylation of the plasmid with the spiroplasma methylase M · SssI, which methylates all ĊpG sites, resulted in complete inhibition of CAT activity. The promoter sequence contains 16 CpG sites and 13 CpNpG sites that are known to be methylation sites in plant DNA. In the light of this fact, and considering the results of the experiments presented here, we conclude that methylation at all ĊpG sites leaving CpNpG sites unmethylated is sufficient to block gene activity in a plant cell. Methylation of ĊpNpG sites in plant cells may, therefore, play a role other than gene silencing.
KW - CpNpG methylation
KW - DNA methylation
KW - M · HpaII/HhaI methylation
KW - M · SssI methylation
KW - microinjected Xenopus oocytes
KW - plant cell transfection
KW - plant promoter regulation
UR - http://www.scopus.com/inward/record.url?scp=0025251146&partnerID=8YFLogxK
U2 - 10.1016/0378-1119(90)90386-6
DO - 10.1016/0378-1119(90)90386-6
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C2 - 2258051
AN - SCOPUS:0025251146
SN - 0378-1119
VL - 94
SP - 189
EP - 193
JO - Gene
JF - Gene
IS - 2
ER -