How prevalent are lactoferrin receptors in Gram-negative bacteria?

Area of Science:

• Microbiology
• Molecular Biology
• Evolutionary Biology

Background:

• Surface receptors for host iron glycoproteins, transferrin (Tf) and lactoferrin (Lf), were first identified in pathogenic bacteria 35 years ago.
• These receptors are essential for Gram-negative bacteria residing on mucosal surfaces to acquire iron for survival.
• The evolutionary history suggests Tf receptors arose over 320 million years ago, with Lf receptors evolving later from Tf receptors.

Purpose of the Study:

• To investigate the prevalence of transferrin (Tf) and lactoferrin (Lf) receptors in commensal bacterial species.
• To understand the evolutionary origins and diversification of bacterial iron acquisition systems.
• To explore the potential presence of these receptors in additional bacterial lineages beyond known pathogens.

Main Methods:

• Comparative genomics analysis to identify Tf and Lf receptor genes across diverse bacterial lineages.
• Phylogenetic analysis to reconstruct the evolutionary history of these receptors.
• Literature review focusing on the discovery and characterization of bacterial iron uptake mechanisms.

Main Results:

• Bacterial Tf and Lf receptors are ancient, with Tf receptors predating Lf receptors by millions of years.
• The specificity of Tf receptors is shaped by host selective pressures, indicating co-evolution.
• Limited understanding exists regarding the prevalence of these receptors in commensal bacteria compared to pathogens.

Conclusions:

• Bacterial Tf and Lf receptors represent ancient iron acquisition strategies with deep evolutionary roots.
• Further research is needed to determine the full extent of Tf and Lf receptor distribution in both pathogenic and commensal bacteria.
• The Lf receptor offers a secondary iron acquisition pathway and potential protection against host defense mechanisms, influencing its varied presence across bacterial lineages.