A code beyond DNA

The encryption of genetic data in the DNA – the so called genetic code – is known for a long time. The existence of a so-called “Histone-code” that influences the interpretation of genetic information via modification of DNA-structure proteins is much more controversial. Scientists of the  Max-Planck-institute for molecular genetics discovered evidence for the existence of such code. In the actual issue of the magazine Genomics they state that transcription-rate of certain genes can be controlled via chemical modification of histones [Fischer, J.J. et al., Genomics 2007, doi 10.1016/j.ygeno.2007.08.010].

DNA of an organism is identical in each cell. In order to produce different organs and tissue, different parts of the DNA are interpreted and transcribed into proteins. The first step of this process, the interpretation of the DNA, is the transcription. Its regulation is decisive for the growing of different organs, bones and muscles form identical DNA.

Within the cell the DNA close to a certain group of proteins, the so-called histones. The negatively charged DNA molecules are wrapped upon the positively charged histones, resulting in an extreme compression of the DNA’s length. For a long time scientists regarded packing of the DNA to be the only purpose of histones. Meanwhile the impact of the concentration of DNA-packing on the amount of interpretation and transcription into proteins of the DNA has been acknowledged. The lower the bond between DNA and histones the higher the rate of transcription of DNA. The intensity of interaction between histones and DNA is crucially affected by chemical modifications at the ends of the histones.

Scientists of the Max-Planck-institute for molecular genetics have studied four different modifications of histones in cells of heart and skeleton-muscles. The scientists lead by Dr. Silke Sperling found out that certain combinations of modifications are linked with different transcription-rates. Influence of specific combinations on transcription was higher than the sum of effects of each single modification. Results reinforced the theory that there is a “Histon-code”, complementing the genetic code and indicating, at which moment and how intense a gene should be read.

Original publication:

J.J. Fischer, J. Toedling, M. Schueler, W. Huber, S. Sperling. Combinatorial effects of four histone modifications in transcription and differentiation. Genomics 2007, doi 10.1016/j.ygeno.

Contact:
Dr. Patricia Marquardt
Max-Planck-Institut für molekulare Genetik
Phone 0049-30-8413 1716
Mail: patricia.marquardt@molgen.mpg.de