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Association of the Cold Shock DEAD-Box RNA Helicase RhlE to the RNA Degradosome in Caulobacter crescentus

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Aguirre, Angel A. ; Vicente, Alexandre M. ; Hardwick, Steven W. ; Alvelos, Daniela M. ; Mazzon, Ricardo R. ; Luisi, Ben F. ; Marques, Marilis V.
Número total de Autores: 7
Tipo de documento: Artigo Científico
Fonte: Journal of Bacteriology; v. 199, n. 13 JUL 2017.
Citações Web of Science: 6

In diverse bacterial lineages, multienzyme assemblies have evolved that are central elements of RNA metabolism and RNA-mediated regulation. The aquatic Gram-negative bacterium Caulobacter crescentus, which has been a model system for studying the bacterial cell cycle, has an RNA degradosome assembly that is formed by the endoribonuclease RNase E and includes the DEAD-box RNA helicase RhlB. Immunoprecipitations of extracts from cells expressing an epitope-tagged RNase E reveal that RhlE, another member of the DEAD-box helicase family, associates with the degradosome at temperatures below those optimum for growth. Phenotype analyses of rhlE, rhlB, and rhlE rhlB mutant strains show that RhlE is important for cell fitness at low temperature and its role may not be substituted by RhlB. Transcriptional and translational fusions of rhlE to the lacZ reporter gene and immunoblot analysis of an epitope-tagged RhlE indicate that its expression is induced upon temperature decrease, mainly through posttranscriptional regulation. RNase E pulldown assays show that other proteins, including the transcription termination factor Rho, a second DEAD-box RNA helicase, and ribosomal protein S1, also associate with the degradosome at low temperature. The results suggest that the RNA degradosome assembly can be remodeled with environmental change to alter its repertoire of helicases and other accessory proteins. IMPORTANCE DEAD-box RNA helicases are often present in the RNA degradosome complex, helping unwind secondary structures to facilitate degradation. Caulobacter crescentus is an interesting organism to investigate degradosome remodeling with change in temperature, because it thrives in freshwater bodies and withstands low temperature. In this study, we show that at low temperature, the cold-induced DEAD-box RNA helicase RhlE is recruited to the RNA degradosome, along with other helicases and the Rho protein. RhlE is essential for bacterial fitness at low temperature, and its function may not be complemented by RhlB, although RhlE is able to complement for rhlB loss. These results suggest that RhlE has a specific role in the degradosome at low temperature, potentially improving adaptation to this condition. (AU)

Processo FAPESP: 14/04046-8 - Sistemas regulatórios da resposta bacteriana a estresses
Beneficiário:Marilis Do Valle Marques
Linha de fomento: Auxílio à Pesquisa - Temático
Processo FAPESP: 14/13552-4 - Estudo da RNA helicase da família DEAD-box codificada pelo gene CC0835 em Caulobacter crescentus
Beneficiário:Alexandre Magno Vicente
Linha de fomento: Bolsas no Brasil - Mestrado