Asked 19th Jan, 2023

Which Proteins are responsible for protein-DNA compaction?

I have certain queries regarding plasmid-DNA transport inside the cell and would be glad if anyone could help me out. 1) As we know there are several proteins/components, which bind DNA specifically or non-specifically and are responsible for DNA compaction inside the cytoplasm. Among those, which are the ones that go inside the pore and make sure that DNA remains in compact form? 2) If proteins responsible for DNA compaction don’t go inside NPC pore except transportin/importins/Ran then how DNA is able to maintain its compact shape throughout the NPC translocation process? Regards -Manoj

All Answers (3)

19th Jan, 2023
Nicolò M. Villa
Swedish University of Agricultural Sciences
  1. Several proteins are responsible for DNA compaction inside the cytoplasm. These include histones, which form nucleosomes, and non-histone proteins such as HMG proteins. The specific proteins that go inside the Nuclear Pore Complex (NPC) pore and ensure that DNA remains in a compact form during transport into the nucleus are the importin and transportin proteins. These proteins bind specifically to the nuclear localization signals (NLS) present on the DNA-associated proteins and mediate their transport through the NPC pore.
  2. The NPC is a large protein complex that spans the nuclear envelope and regulates the transport of macromolecules between the cytoplasm and the nucleus. The NPC is composed of multiple copies of several different types of proteins, including nucleoporins, which form the NPC pore. During transport, importin and transportin proteins bind to the NLS present on the DNA-associated proteins and mediate their transport through the NPC pore. As these proteins and DNA-associated proteins pass through the NPC, the nucleoporins form a tight pore around the transported molecules and help maintain the compact shape of the DNA. Additionally, it is thought that the energy from the hydrolysis of the GTPase Ran and its associated transportin may also help to maintain the compact shape of the DNA as it is transported through the NPC.
19th Jan, 2023
Sushanta Sethi
Indian Institute of Technology Bombay
Nicolò M. Villa thanks for your quick response. Could you please provide references for the same? Secondly, how much role does the concentration of salt play in such cases?
19th Jan, 2023
Malcolm Nobre
Advanced Centre for Treatment, Research and Education in Cancer
Please refer to the articles attached below. It may be helpful.

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