G2/M-Phase–Specific Transcription during the Plant Cell Cycle Is Mediated by c-Myb–Like Transcription Factors
AUTOR(ES)
Ito, Masaki
FONTE
American Society of Plant Biologists
RESUMO
Plant B-type cyclin genes are expressed specifically in late G2- and M-phases during the cell cycle. Their promoters contain a common cis-acting element, called the MSA (M-specific activator) element, that is necessary and sufficient for periodic promoter activation. This motif also is present in the tobacco kinesin-like protein gene NACK1, which is expressed with timing similar to that of B-type cyclin genes. In this study, we show that G2/M-phase–specific activation of the NACK1 promoter also is regulated by the MSA element, suggesting that a defined set of G2/M-phase–specific genes are coregulated by an MSA-mediated mechanism. In a search for MSA binding factors by yeast one-hybrid screening, we identified three different Myb-like proteins that interact specifically with the MSA sequence. Unlike the majority of plant Myb-like proteins, these Myb proteins, NtmybA1, NtmybA2, and NtmybB, have three imperfect repeats in the DNA binding domain, as in animal c-Myb proteins. During the cell cycle, the level of NtmybB mRNA did not change significantly, whereas the levels of NtmybA1 and A2 mRNAs fluctuated and peaked at M-phase, when B-type cyclin genes were maximally induced. In transient expression assays, NtmybA1 and A2 activated the MSA-containing promoters, whereas NtmybB repressed them. Furthermore, expression of NtmybB repressed the transcriptional activation mediated by NtmybA2. Our data show that a group of plant Myb proteins that are structurally similar to animal c-Myb proteins have unexpected roles in G2/M-phase by modulating the expression of B-type cyclin genes and may regulate a suite of coexpressed genes.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=139135Documentos Relacionados
- M-phase-specific phosphorylation of the POU transcription factor GHF-1 by a cell cycle-regulated protein kinase inhibits DNA binding.
- Plk is an M-phase-specific protein kinase and interacts with a kinesin-like protein, CHO1/MKLP-1.
- c-Myc Is Necessary for DNA Damage-Induced Apoptosis in the G2 Phase of the Cell Cycle
- Control of Cyclin G2 mRNA Expression by Forkhead Transcription Factors: Novel Mechanism for Cell Cycle Control by Phosphoinositide 3-Kinase and Forkhead
- Actinobacillus actinomycetemcomitans Toxin Induces Both Cell Cycle Arrest in the G2/M Phase and Apoptosis