Caracterización de NfeD en Staphylococcus aureus: Una nueva proteína implicada en la formación de los microdominios de membrana.

• Autores: Lara Kricks
• Directores de la Tesis: Daniel López Serrano (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2021
• Idioma: español
• Número de páginas: 155
• Tribunal Calificador de la Tesis: José Berenguer Carlos (presid.), Diego Francisco Romero Hinojosa (secret.), Felipe Cava (voc.)
• Programa de doctorado: Programa de Doctorado en Biociencias Moleculares por la Universidad Autónoma de Madrid
• Materias:
  • Ciencias de la vida
    • Biología molecular
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Bacteria exhibit microdomains in their membranes that serve as platforms for signal transduction, similar to ‘lipid rafts’ in eukaryotes. Functional Membrane Microdomains (FMM) are characterized by the accumulation of proteins functioning in signal transduction, lipids that differ from the rest of the membrane, and the scaffold protein, flotillin. FMM formation in the pathogen S. aureus depends on the accumulation of staphyloxanthin, the co-localization with flotillin and its organization into oligomers (Garcia-Fernández et al., 2017).

    In bacteria, the gene encoding the scaffold protein flotillin is frequently co- transcribed with the NfeD protein (Green et al., 2004). NfeD proteins are absent in eukaryotes and exist as mainly two variants (Green et al., 2009). One that exhibits protease activity at its N-terminus, and a shorter form lacking the protease activity. The shorter form harbours transmembrane regions and a ‘NfeD- domain’ as common feature of all NfeD proteins. The ‘NfeD-domain’ is a five- stranded b-barrel, similar to an OB (Oligonucleotide/ Oligosaccharide binding)- fold domain (Walker et al., 2008; Kuwahara et al., 2008). However, the OB-fold of the NfeD proteins’ analyzed to date lack the surface residues, responsible for nucleotide binding. Although the function of NfeD proteins is not clear yet, the fact that they share an operon with flotillins suggests a functional relation and even a physical interaction of both proteins (Green et al., 2004). Here we characterize the NfeD protein functionally and structurally, to analyze its impact on FMM formation and integrity.

    In this work, we identify the NfeD protein in S. aureus as a new structural component of FMM involved in FMM biogenesis and integrity. We show, that the NfeD protein in S. aureus is a short NfeD variant that lacks the protease activity. We further observe that the NfeD protein in S. aureus is a membrane protein that preferentially localizes in membrane foci. The NfeD protein localizes indepently of flotillin to FMM where it assembles into homooligomers. NfeD homooligomers are facilitated by the OB-fold. NfeD and flotillin physically interact and form hetero-oligomers. Moreover, NfeD impacts flotillin stability and recruits flotillin into FMM. The absence of nfeD results in attenuated virulence of S. aureus.