As an emerging hot topic in biological research, epigenetics describes inheritable changes in phenotype (appearance) or gene expression caused by mechanisms other than permanent changes in DNA sequence. In current researches, due to lack of effective observing tools and methods, it is still a challenge to probe involved epigenetic modifications in cells in a convenient, quick and non-invasive way.

A study team led by Prof. HUANG Qing in Institute of Technical Biology & Agriculture Engineering, Hefei Institutes of Physical Sciense (CAHIPS) revealed the significant transformation of B-DNA to Z-DNA upon histone acetylation in the TSA treated HeLa cells by FTIR spectroscopy. Their study entitled Histone acetylation induced transformation of B-DNA to Z-DNA in cells probed through FT-IR spectroscopy was published as a Letter in Analytical Chemistry.

Generally, the double-stranded DNA wrapping histones is right-handed helix B-DNA. However, other kinds of conformation also exist, for example, the Z-DNA which belongs to left-handed helix.

The researchers applied FT-IR spectroscopy to monitor the DNA signals accompanied with histone acetylation in cells. They found that upon histone acetylation, a large number of B-DNA molecules would be transformed to Z-DNA form. The reason for this change may lie in that the acetylation weakens the interaction between histone and DNA, and then, with transcription factors, DNA was easy to form negative supercoil, which is most composed of Z-DNA.

This work may help to understand the function of DNA conformation change in cell division and gene expression. In addition, it demonstrates that FTIR is an effective analytical tool to conduct epigenetics research.

FTIR spectroscopy for monitoring the DNA signals in cells as the histone acetylation was regulated by trichostatin A (TSA), demonstrating that the significant transformation of B-DNA to Z-DNA upon histone acetylation in HeLa cells. (Image by CHEN Zhu)