Non-essential ribosomal proteins in bacteria and archaea identified using COGs

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genomics

Background:

• Ribosomal proteins (RPs) are crucial for bacterial and archaeal survival, yet many genomes lack certain RP genes.
• Previous studies indicated that some RP gene deletions have minimal impact on bacterial growth.
• Prokaryotic genomes exhibit significant variation in RP gene content, with some RPs being non-essential.

Purpose of the Study:

• To systematically analyze the evolutionary conservation and genuine loss of ribosomal protein genes in prokaryotes.
• To identify trends in RP gene loss related to ribosome architecture and assembly.
• To understand the evolutionary constraints and patterns of ribosome evolution in bacteria and archaea.

Main Methods:

• Compiled a list of missing ribosomal genes from the Clusters of Orthologous Genes (COG) database (1,309 prokaryotic genomes).
• Distinguished genuine gene losses from annotation errors and frameshifts.
• Correlated RP gene loss with experimental data on non-essential RPs in model organisms (E. coli, B. subtilis).

Main Results:

• Approximately half of all RPs are universally conserved; up to 16 RPs are missing in some prokaryotic genomes.
• Genuine RP gene losses are prevalent, particularly in small genomes (<1 Mb) of host-associated bacteria and archaea.
• Frequently lost RPs are located on the ribosome periphery and are often non-essential, showing overlap between computational and experimental findings.

Conclusions:

• Ribosome architecture and assembly order influence RP essentiality and susceptibility to gene loss.
• RPs on the ribosome surface or incorporated late in assembly are more prone to loss during genome compaction.
• Identified common trends and constraints in prokaryotic ribosome evolution, particularly in symbiotic and parasitic lineages.