Multiple modes of DNA compaction by protamine.
Vikhyaat AhlawatHuan-Xiang ZhouPublished in: bioRxiv : the preprint server for biology (2023)
In sperm cells, protamine replaces histones to compact DNA 10-20 times more than in somatic cells. To characterize the extreme compaction, we employed confocal microscopy and optical tweezers to determine the conformations and stability of protamine-bound λ-DNA. Confocal images show increasing compaction of λ-DNA at increasing protamine concentration. In the presence of protamine, single λ-DNA molecules form bends and loops that unravel at 10-40 pN forces as well as coils that shorten the contour length by up to 40% and withstand forces strong enough (~55 pN) for strand separation. Strand separation nucleates coils, indicating protamine insertion into DNA bases. Protamine may participate in both local and higher-order chromatin organization, leading to extreme compaction and global transcription silencing.
Keyphrases
- circulating tumor
- cell free
- single molecule
- induced apoptosis
- nucleic acid
- transcription factor
- cell cycle arrest
- climate change
- dna damage
- gene expression
- deep learning
- cell proliferation
- cell death
- genome wide
- mass spectrometry
- endoplasmic reticulum stress
- dna methylation
- liquid chromatography
- copy number
- convolutional neural network
- raman spectroscopy