RNA polymerase I holoenzyme-promoter complexes include an associated CK2-like protein kinase.
In eukaryotes, RNA polymerase I (pol I) transcribes the tandemly repeated genes that encode the precursor of 18S, 5.8S and 25S ribosomal RNAs. In plants and animals, the pol I enzyme can be purified in a holoenzyme form that is self-sufficient for promoter binding and accurate, promoter-dependent transcription in a cell-free system. In this report, we show that a casein kinase 2 (CK2)-like protein kinase co-purifies with pol I holoenzyme activity purified from broccoli (Brassica oleracea). Using an immobilized template assay, we show that the CK2-like activity is part of the protein-DNA complex that results upon binding of the holoenzyme to the rRNA gene promoter. The CK2 activity phosphorylates a similar set of holoenzyme proteins both before and after promoter binding. These data provide further evidence that pol I holoenzyme activity can be attributed to a single, multi-protein complex self-sufficient for promoter association and accurate, promoter-dependent transcription.
Saez-Vasquez
J
J
Biology Department, Washington University, St. Louis, MO, 63130, USA.
Meissner
M
M
Pikaard
C S
CS
D001937:Brassica / Q000201:enzymology / Q000235:genetics; D047390:Casein Kinase II; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism*; D020035:Holoenzymes / Q000302:isolation & purification / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D012318:RNA Polymerase I / Q000302:isolation & purification / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics; D013379:Substrate Specificity; D014158:Transcription, Genetic
D018744:DNA, Plant; D020035:Holoenzymes; D012335:RNA, Ribosomal; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D012318:RNA Polymerase I