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

Bacterial chromosomal gene positioning is likely shaped by selection on both mean and growth-dependent expression, with significant gradients observed in multiple datasets.

• Why it matters: Understanding how gene position influences expression can reveal mechanisms of bacterial adaptation and evolution, addressing gaps in knowledge about chromosomal organization.
• What they did: The study analyzed eight multi-environment protein expression datasets from three bacterial species and Escherichia coli promoter strengths, focusing on mean expression and expression slope across the chromosome.
• The result: Both mean expression and growth-dependent expression gradients decrease from oriC to ter, but combined hypotheses explain only a small fraction of gene positioning, suggesting moderate selection effects on gene placement.