Escherichia coli small heat shock protein IbpA is an aggregation-sensor that self-regulates its own expression at posttranscriptional levels.
Mol Microbiol
; 115(1): 142-156, 2021 01.
Article
en En
| MEDLINE
| ID: mdl-32959419
ABSTRACT
Aggregation is an inherent characteristic of proteins. Risk management strategies to reduce aggregation are critical for cells to survive upon stresses that induce aggregation. Cells cope with protein aggregation by utilizing a variety of chaperones, as exemplified by heat-shock proteins (Hsps). The heat stress-induced expression of IbpA and IbpB, small Hsps in Escherichia coli, is regulated by the σ32 heat-shock transcriptional regulator and the temperature-dependent translational regulation via mRNA heat fluctuation. We found that, even without heat stress, either the expression of aggregation-prone proteins or the ibpA gene deletion profoundly increases the expression of IbpA. Combined with other evidence, we propose novel mechanisms for the regulation of the small Hsps expression. Oligomeric IbpA self-represses the ibpA/ibpB translation, and mediates its own mRNA degradation, but the self-repression is relieved by sequestration of IbpA into the protein aggregates. Thus, the function of IbpA as a chaperone to form co-aggregates is harnessed as an aggregation sensor to tightly regulate the IbpA level. Since the excessive preemptive supply of IbpA in advance of stress is harmful, the prodigious and rapid expression of IbpA/IbpB on demand is necessary for IbpA to function as a first line of defense against acute protein aggregation.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Regulación Bacteriana de la Expresión Génica
/
Proteínas de Escherichia coli
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Agregado de Proteínas
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Proteínas de Choque Térmico
Idioma:
En
Revista:
Mol Microbiol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
MICROBIOLOGIA
Año:
2021
Tipo del documento:
Article
País de afiliación:
Japón