Bacterial chromosomal gene positioning is likely shaped by selection on both mean and growth-dependent expression

The useful part

Hence, mutations altering a gene's chromosomal position can affect its expression level and be subject to selection. Two non–mutually exclusive hypotheses regarding the target of this selection have been proposed. In regression models predicting gene position, the relative contributions of the two hypotheses differ across species.

How it works

• However, even when combined, the two hypotheses explain only a small fraction of chromosomal gene positioning, in part because the replication-dose effect is incompletely offset by compensatory evolution of...
• The positional gradients in mean and growth-dependent expression are disproportionately contributed by genes involved in translation and transcription.
• We conclude that patterns of bacterial chromosomal gene positioning are consistent with moderate effects of selection on both mean and growth-dependent expression.

Details worth keeping

by Ruiqi Yuan, Jianzhi Zhang In bacteria with circular chromosomes, genes near the replication origin (oriC) are replicated earlier and consequently attain higher copy numbers than genes near the terminus (ter), particularly during rapid growth.