Chromosomal Position of Ribosomal Protein Genes Affects Long-Term Evolution of Vibrio cholerae

Area of Science:

• Microbiology
• Evolutionary Biology
• Genomics

Background:

• Bacteria strategically cluster transcription and translation genes near the replication origin (oriC).
• The relative positioning of the ribosomal protein gene locus (S10) to oriC influences bacterial growth, fitness, and infectivity.

Purpose of the Study:

• To investigate the long-term evolutionary consequences of S10 locus positioning relative to oriC in Vibrio cholerae.
• To determine if suppressor mutations can compensate for suboptimal gene placement over evolutionary timescales.

Main Methods:

• Evolving 12 populations of V. cholerae with S10 at oriC-proximal or oriC-distal locations for 1,000 generations.
• Monitoring genetic mutations, growth rates, and fitness across evolved populations.
• Sequencing and characterizing mutations in fastest-growing clones.

Main Results:

• All populations showed increased growth rates, but oriC-proximal strains consistently maintained higher fitness.
• Inactivating mutations accumulated in virulence-related genes (flagellum, chemotaxis, biofilm, quorum sensing).
• Mutations conferring a ≈10% growth improvement were identified in flagellum master regulators.

Conclusions:

• The genomic location of ribosomal protein genes is a critical determinant of V. cholerae's evolutionary trajectory.
• Gene order, often underestimated, significantly shapes bacterial physiology and evolution, with gene content being more plastic.
• Artificial manipulation of gene order offers potential for bacterial genetic circuit reprogramming and growth modulation.