protein/DNA methylation interaction - (Nov/19/2008 )
hi guys,
on my literature review i came with this doubt that i'd like to ask here. i'm interested in this compound that gets deactivated by methylation when it is under pathogen attack, but nothing is known about the DNA methylation state of the gene enconding this compound. however, it would make sense that this gene is being silenced by DNA methylation/histone modifications under the condition mentioned earlier.
is any of you aware of the relationship between deactivation by methylation of a specific protein/compound and the DNA methylation state of the encoding gene?
many thanks.
tj
happens all the time and there is a correlation between DNA Methylation of the gene promoter and gene expression.
just look up tumor suppressor genes in cancer, X-inactivated genes and of course imprinted genes where you get allele specific expression of the imprinted gene.
It's everywhere you look!
Nick
hi methylnick,
i'm aware that there is a strong correlation between DNA methylation of the gene promoter and its expression, but you'll see, i found out that there is this protein that is deactivated by methylation, so it is actually the protein that is being methylated. about the gene encoding this protein or its promoter region it is not know whether it also contains methylation at the DNA level or not when the protein is being methylated.
do you think there might be any kind of feedback between the methylated protein and its encoding gene at the DNA level? or it might have nothing to do, because the methyltransferase affecting the protein is not directly related to the DNA methyltransferases, actually it would be interesting to search for common motifs between these kinds of mt's to get a first insight, and it would be really interesting to find out if there is a correlation between the methylated protein and the methylated DNA!
thanks methylnick! i really appreciate your comments.
tj
....relationship between deactivation by methylation of a specific protein/compound and the DNA methylation state of the encoding gene?
So, what exactly is the compound you are referring to? I'm assuming it a specific protein or group of proteins; so then the protein itself would be methylated? I know that methylation of histone tails is associated with the recruitment of DNA methyltransferases, which then methylate the associated DNA. But I have not heard about a gene product (protein) being methylated to become inactivated (a protein methyltransferase would have to do it, I guess? never heard of those either). Very interesting!
so the protein is methylated and the question is whether this modification in turn methylates the gene promoter from which it were derived from? As k_undertoe said you could envison this to be the case for histone tail modifications whereby it is methylated and then the methylated histone recruits the silencing complexes that then turn off the gene promoter. Would this be the case for histones? maybe not as it should always be on to there is enough of the histone to be around for replication.
Other proteins? I haven't heard of any either. But one way to test this would be to IP the protein with and without the modifciation to see what other proteins are binding and whether or not and DNMT is interacting with your protein of interest.
Nick
this is the reference i was telling you about, it is about gibberellins methylation in arabidopsis
http://www.plantcell.org/cgi/content/full/19/1/32
unsurprisingly, the GA's methylation is also through SAM. i stil have a lot to read 
cheers,
tj