MCM molecules impede the formation of DNA loops

The entire genomic material of a cell must be packed into a tiny cell nucleus in such a way that it can be stored in an organized manner and that it can be transcribed, duplicated or repaired as needed. The space-saving packaging can roll up or loop the DNA. The exact function and task of these machines are being investigated by scientists. The three-dimensional structure of the genome and the role of the MCM complex in restriction of DNA loop formation were discovered by them.

A two meter long DNA molecule has to be packed into a tiny cell nucleus. A cell nucleus is the size of a fine dust particle. How does it work? How can the genetic information be stored and read at the same time? How is it put together? Dynamic processes such as packaging and unpacking need to run quickly and smoothly.

Tachibana, the new director of the department of Totipotency at the Max Planck Institute of Biochemistry, and her team discovered that aProtein complex well known for its function in DNA replication has an unexpected role in genome folding. We decided to join forces to use different approaches to investigate the initial observations. Karl Duderstadt is the head of the research group.

There is a new class of barriers.

The minichromosome maintenance complex has been identified as a new class of barriers in the formation of DNA loops. In the process of DNA loop formation, the first cohesin, second zinc finger and third MCM complex are involved. The formation of a loop is initiated by cohesin. The progressive growth of a loop is caused by cohesin coiling the DNA.

Although the details differ, one can imagine that it is a little like threading a ribbon through a ring. Tachibana explains that the MCMs are different from the CTCF, which is a vertebrate-specific barrier. The work raises the possibility that the encounters of loop extruding cohesin complexes with MCM complexes are part of a fundamental mechanism that organizes the genome folding of a wide variety of organisms.

The discovery was only possible because of the formation of an amazing international team with expertise in a broad range of areas. This work shows what can be accomplished when you build bridges. I am certain that there will be many more surprises for us as we explore deeper into the network of interactions that control chromosome organization.

The study was published in Nature.

More information: Bart J. H. Dequeker et al, MCM complexes are barriers that restrict cohesin-mediated loop extrusion, Nature (2022). DOI: 10.1038/s41586-022-04730-0 Journal information: Nature Citation: MCM molecules impede the formation of DNA loops (2022, May 20) retrieved 20 May 2022 from https://phys.org/news/2022-05-mcm-molecules-impede-formation-dna.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.