Nucleoid Size Scaling and Intracellular Organization of Translation Across Bacteria

Abstract

The scaling of organelles with cell size is thought to be exclusive to eukaryotes. Here, we demonstrate that similar scaling relationships hold for the nucleoid in bacteria. Despite the absence of a nuclear membrane, nucleoid size strongly correlates with cell size, independent of changes in DNA amount and across various nutrient conditions. This correlation is observed in diverse bacteria, revealing a near-constant ratio between nucleoid and cell size for a given species. As in eukaryotes, the nucleocytoplasmic ratio in bacteria varies greatly among species. This spectrum of nucleocytoplasmic ratios is independent of genome size, and instead appears linked to the average cell size of the population. Bacteria with different nucleocytoplasmic ratios have different biophysical properties of the cytoplasm, impacting the mobility and localization of ribosomes. Together, our findings identify new organizational principles and biophysical features of bacterial cells, implicating the nucleocytoplasmic ratio and cell size as determinants of the intracellular organization of translation.

Keywords: Nucleoid, nucleocytoplasmic ratio, scaling properties, cell size, ribosome mobility, intracellular organization