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

Bacterial gene positioning is shaped by selection on both mean and growth-dependent expression, with gradients observed across multiple species and conditions.

• Why it matters: Understanding how gene location influences expression helps clarify bacterial adaptation and evolution, addressing gaps in knowledge about the forces shaping chromosomal organization.
• What they did: The study analyzed eight multi-environment datasets from three bacterial species and promoter strengths in Escherichia coli, testing hypotheses about gene position effects on expression levels and growth dependence.
• The result: Both mean and growth-dependent expression gradients are evident and contribute to gene positioning, especially in translation and transcription genes, though their overall impact is moderate due to compensatory evolution.