Lipopolysaccharides promote binding and unfolding of the antibacterial colicin E3 rRNAse domain.
Biochim Biophys Acta Biomembr
; 1859(12): 2454-2460, 2017 Dec.
Article
en En
| MEDLINE
| ID: mdl-28888366
ABSTRACT
Nuclease colicins are antibacterial proteins produced by certain strains of E. coli to reduce competition from rival strains. These colicins are generally organized with an N-terminal transport (T)-domain, a central receptor binding (R)-domain, and a C-terminal cytotoxic nuclease domain. These colicins are always produced in complex with an inhibitory immunity protein, which dissociates prior entrance of the cytotoxic domain in the target cell. How exactly colicins traverse the cell envelope is not understood, yet this knowledge is important for the design of new antibacterial therapies. In this report, we find that the cytotoxic rRNAse domain of colicin E3, lacking both T- and R-domains, is sufficient to inhibit cell growth provided the immunity protein Im3 has been removed. Thus, while the T-domain is needed for dissociation of Im3, the rRNAse alone can associate to the cell surface without R-domain. Accordingly, we find a high affinity interaction (Kd ~1-2µM) between the rRNAse domain and lipopolysaccharides (LPS). Furthermore, we show that binding of ColE3 to LPS destabilizes the secondary structure of the toxin, which is expectedly crucial for transport through the narrow pore of the porin OmpF. The effect of LPS on binding and unfolding of ColE3 may be indicative of a broader role of LPS for transport of colicins in general.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Regulación Bacteriana de la Expresión Génica
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Lipopolisacáridos
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Proteínas de Unión al ARN
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Porinas
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Colicinas
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Proteínas de Escherichia coli
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Proteínas de Unión al ADN
Idioma:
En
Revista:
Biochim Biophys Acta Biomembr
Año:
2017
Tipo del documento:
Article
País de afiliación:
Canadá