A low Smc flux avoids collisions and facilitates chromosome organization in Bacillus subtilis

eLife

Stephan Gruber¹  Florian Patrick Bock¹  Anna Anchimiuk¹  Anita Minnen²  Virginia S Lioy³  Frederic Boccard³ 

[1] Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland;Max Planck Institute of Biochemistry, Martinsried, Germany;Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France;

关键词: SMC complexes;    chromosome organization;    chromosome condensation;    DNA loop extrusion;    chromosome segregation;    ParABS;    B. subtilis;   

DOI  :  10.7554/eLife.65467

来源: eLife Sciences Publications, Ltd

【 摘 要 】

SMC complexes are widely conserved ATP-powered DNA-loop-extrusion motors indispensable for organizing and faithfully segregating chromosomes. How SMC complexes translocate along DNA for loop extrusion and what happens when two complexes meet on the same DNA molecule is largely unknown. Revealing the origins and the consequences of SMC encounters is crucial for understanding the folding process not only of bacterial, but also of eukaryotic chromosomes. Here, we uncover several factors that influence bacterial chromosome organization by modulating the probability of such clashes. These factors include the number, the strength, and the distribution of Smc loading sites, the residency time on the chromosome, the translocation rate, and the cellular abundance of Smc complexes. By studying various mutants, we show that these parameters are fine-tuned to reduce the frequency of encounters between Smc complexes, presumably as a risk mitigation strategy. Mild perturbations hamper chromosome organization by causing Smc collisions, implying that the cellular capacity to resolve them is limited. Altogether, we identify mechanisms that help to avoid Smc collisions and their resolution by Smc traversal or other potentially risky molecular transactions.

【 授权许可】

CC BY