Defined chromosome structure in the genome-reduced bacterium Mycoplasma pneumoniae

Nat Commun. 2017 Mar 8;8:14665. doi: 10.1038/ncomms14665.

Abstract

DNA-binding proteins are central regulators of chromosome organization; however, in genome-reduced bacteria their diversity is largely diminished. Whether the chromosomes of such bacteria adopt defined three-dimensional structures remains unexplored. Here we combine Hi-C and super-resolution microscopy to determine the structure of the Mycoplasma pneumoniae chromosome at a 10 kb resolution. We find a defined structure, with a global symmetry between two arms that connect opposite poles, one bearing the chromosomal Ori and the other the midpoint. Analysis of local structures at a 3 kb resolution indicates that the chromosome is organized into domains ranging from 15 to 33 kb. We provide evidence that genes within the same domain tend to be co-regulated, suggesting that chromosome organization influences transcriptional regulation, and that supercoiling regulates local organization. This study extends the current understanding of bacterial genome organization and demonstrates that a defined chromosomal structure is a universal feature of living systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Structures
  • Chromosomes, Bacterial / ultrastructure*
  • DNA, Bacterial / ultrastructure*
  • DNA, Superhelical / ultrastructure*
  • Gene Expression Regulation, Bacterial*
  • Genome, Bacterial / genetics*
  • Microscopy
  • Molecular Conformation
  • Mycoplasma pneumoniae / genetics*
  • Mycoplasma pneumoniae / ultrastructure
  • Nucleic Acid Conformation

Substances

  • DNA, Bacterial
  • DNA, Superhelical