Molecular and structural basis of oligopeptide recognition by the Ami transporter system in pneumococci

ATP-binding cassette (ABC) transport systems are crucial for bacteria to ensure sufficient uptake of nutrients that are not produced de novo or improve the energy balance. The cell surface of the pathobiont Streptococcus pneumoniae (pneumococcus) is decorated with a substantial array of ABC transporters, critically influencing nasopharyngeal colonization and invasive infections. Given the auxotrophic nature of pneumococci for certain amino acids, the Ami ABC transporter system, orchestrating oligopeptide uptake, becomes indispensable in host compartments lacking amino acids. The system comprises five exposed Oligopeptide Binding Proteins (OBPs) and four proteins building the ABC transporter channel. This work has been led by the groups directed by Juan Hermoso (IQF-CSIC) and Sven Hammerschmidt (University of Greifswald, Germany), with the collaboration of the groups led by Isabel Usón (IBMB-CSIC), Larry McDaniel (University of Mississippi, USA) and María-José Camarasa (IQM-CSIC). The study, published now in PLOS Pathogens journal, presents a comprehensive analysis of the initial phase of peptide transport mediated by OBPs within the pneumococcal Ami permease system. It discloses a common mechanism for oligopeptide recognition that is modulated in each OBP to accommodate a diverse array of oligopeptides; also, a mechanism for membrane transport is proposed. Understanding how pneumococcus perceives external stimuli and responds to them is imperative for unraveling the transition from the commensal to the pathogenic state. Reference: Alcorlo M, Abdullah MR, Steil L, Sotomayor F, López-de Oro L, de Castro S, et al. (2024) Molecular and structural basis of oligopeptide recognition by the Ami transporter system in pneumococci. PLoS Pathog 20(6): e1011883. https://doi.org/10.1371/journal.ppat.1011883