Video Experimental Relacionado
Updated: May 30, 2026
06:37
Staphylococcus aureus Growth using Human Hemoglobin as an Iron Source
Published on: February 7, 2013
Los complejos proteína-proteína débiles transitorios transfieren el hemo a través de la pared celular de
Valerie A Villareal1, Thomas Spirig, Scott A Robson
1Department of Chemistry and Biochemistry and the UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095, USA.
Journal of the American Chemical Society
|August 13, 2011
Resumen
El Staphylococcus aureus captura el hierro a través del hemo utilizando las proteínas Isd. Los estudios estructurales revelan un rápido mecanismo de transferencia de hemo entre las hemoproteínas IsdA e IsdC a través de un complejo transitorio de "apretón de manos".
Área de la Ciencia:
- Microbiología Microbiología.
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
Sus antecedentes:
- El hierro es esencial para la virulencia de Staphylococcus aureus.
- El hemo de la hemoglobina es una fuente primaria de hierro durante la infección.
- Las proteínas determinantes superficiales reguladas por el hierro (Isd) median la absorción de hemo en S. aureus.
Objetivo del estudio:
- Para dilucidar el mecanismo de transferencia de hemo entre las hemoproteínas IsdA e IsdC.
- Determinar la base estructural del proceso de transferencia rápida de hemo.
Principales métodos:
- Se utilizaron métodos de mejora de la relajación paramagnética (PRE) por resonancia magnética nuclear (RMN) para modelar la estructura del complejo IsdA:heme:IsdC.
- Para validar el modelo se emplearon mediciones de flujo detenido y mutagénesis dirigida de aminoácidos.
Principales resultados:
- La transferencia de hemo se produce a través de un complejo de afinidad ultra débil de "apretón de manos" que involucra hélices yuxtapuestas 3(10) y bucles β7/β8 de IsdA e IsdC.
- Se identificaron complejos transitorios de encuentro de pre-equilibrio de alta energía, que preceden al complejo estereospecífico de apretón de manos.
- La mutagenesis de los residuos interfaciales redujo significativamente la tasa de transferencia de hemo, confirmando la relevancia funcional del modelo.
Conclusiones:
- El sistema Isd facilita la transferencia rápida de hemo a través de interacciones específicas proteína-proteína y de intermediarios transitorios.
- Los dominios NEAR Transporter (NEAT) involucrados en la unión del hemo se conservan en las bacterias patógenas Gram-positivas.
- Se pueden emplear mecanismos similares para la transferencia de hemo en otros microbios patógenos.
Videos de Conceptos Relacionados
01:26Bacterial Translocation and Protein Secretion
Bacterial protein secretion involves translocation systems to ensure proteins reach their designated locations, including the plasma membrane, periplasm, outer membrane, or the external environment. These translocation systems are vital for bacterial physiology, supporting processes like membrane assembly, enzymatic activity in the periplasm, and interactions with the external environment. The division of labor between Sec and Tat pathways ensures efficiency in handling proteins with diverse...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
01:17Gram-negative Bacterial Protein Secretion Systems
Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
01:20Cotranslational Protein Translocation
Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
01:29Staphylococcal Skin Infections
Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...
01:24Protein Transport to the Stroma
Chloroplasts are triple membrane structures with an outer membrane, an inner membrane, and a thylakoid membrane, each containing distinct metabolite transporters, membrane translocons, and enzymes. Appropriate sorting and translocating these proteins to their correct membrane systems is essential for chloroplast function.
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...