Protamines – histones in disguise

All DNA from yeast to mammals is occupied by histones (H2A, H2B, H3, and H4) and folded into chromatin. Well, not entirely…. Certain types of DNA such as sperm DNA play by their own rules and are actually compacted by proteins other than histones! Most of the paternal DNA in human sperms is compacted with the help of protamines (protamine P1 and P2).  I would still count them as histone-like proteins as protamines are also small (5-8 kDa in [...]

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After Genetics and Epigenetics comes Epitranscriptomics!

The word “epigenetics” is everywhere these days, and you might also have come across the word “epitranscriptomics”. But what is actually meant by these terms and why does it matter? Let’s start with epigenetics: “Epigenetics”, which literally means ‘on top of genetics’, is a term that has taken on multiple meanings in the past. In my understanding, epigenetics describes (heritable) changes in gene expression that do not involve changes to the underlying DNA sequence. Certain epigenetic factors help to define and regulate gene expression [...]

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The rise and fall of the 30 nm fiber

Although the structure of the nucleosome has been solved with atomic resolution, higher-order structures of chromatin remain ill-defined and are still controversial. It was book knowledge for ages – and I was also told so in my own biochemistry lectures – that nucleosomes (i.e. the beads-on-a string structure or the 10 nm fiber) fold and assemble into higher order structures until chromosome-level of compaction is achieved. In this model, the 30 nm fiber represents the next level of compaction. [...]

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Oncohistones are on the rise!

The compaction of DNA into chromatin using the four canonical histones (H3, H2B, H2A, and H4) is crucial in terms of organizing our DNA into the restricted constraints of the cell nucleus. Moreover, PTMs deposited on histones as well as the incorporation of histone variants add an additional layer of complexity and provide means of regulating transcription, replication and DNA repair. But where there is light there is shadow…. Histones have been previously linked to tumorigenesis, primarily through alterations [...]

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In the beginning was the archaeosome …

Where do we come from? This is one of the essential questions to mankind and really tough to answer. The groundbreaking work of Karolin Luger and her colleagues has recently delivered the answer to a question of equal importance (at least to epigenetic researchers): Where do nucleosomes originate from? Findings reported August 2017 in Science suggest that the origins of DNA folding go back to Archaea: they use a single type of histone to wrap their DNA into a complex [...]

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