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Doctoral Thesis
DOI
https://doi.org/10.11606/T.42.2018.tde-22022018-160033
Document
Author
Full name
Angel Alfonso Aguirre Durán
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Marques, Marilis do Valle (President)
Galhardo, Rodrigo da Silva
Gueiros Filho, Frederico José
Maldonado, Gabriel Padilla
Simão, Rita de Cássia Garcia
Title in Portuguese
Caracterização fenotípica de linhagens mutantes das RNA helicases DEAD-box de Caulobacter crescentus em condições de baixa temperatura.
Keywords in Portuguese
Caulobacter crescentus
Estresse frio
Ribossomos
RNA helicases DEAD-box
Abstract in Portuguese
As RNA helicases da família DEAD-box são enzimas que alteram as estruturas secundárias do RNA e auxiliam a formação de complexos ribonucleoproteicos, e são muito importantes em processos basais como a degradação dos RNAs e a biogênese dos ribossomos. A α-proteobactéria criotolerante Caulobacter crescentus é um modelo experimental interessante para compreender o papel destas enzimas em baixa temperatura. A caracterização fenotípica de linhagens mutantes simples de quatro RNA helicases DEAD-box permitiu demonstrar que a RNA helicase RhlE é necessária para o crescimento em baixa temperatura. Os mutantes duplos mostraram redução do crescimento à temperatura normal e em baixa temperatura, com perda de viabilidade e alterações morfológicas. Através de ensaios de complementação cruzada mostrou-se que seus papéis fisiológicos são até certo ponto redundantes. O mutante rhlE também apresentou redução na formação de biofilme. A medida da expressão relativa dos genes que codificam as RNA helicases mostrou um aumento na expressão de três destes genes em estresse frio, e a análise dos perfis ribossomais mostrou a possível participação destas três RNA helicases na biogênese do ribossomo.
Title in English
Phenotypic characterization of mutant lines of DEAD-box RNA helicases from Caulobacter crescentus under low temperature conditions.
Keywords in English
Caulobacter crescentus
Cold stress
DEAD-box RNA helicases
Ribosomes
Abstract in English
The RNA helicases of the DEAD-box family are enzymes that modify RNA secondary structures and help the formation of ribonucleoprotein complexes, and are very important in basal processes such as RNA degradation and ribosome biogenesis. The cryotolerant α-proteobacterium Caulobacter crescentus is an interesting experimental model to understand the role of these enzymes at low temperature. The phenotypic characterization of strains with single mutations of four DEAD-box RNA helicases showed that RNA helicase RhlE is required for growth at low temperature. The double mutants showed reduction in growth at both normal and low temperatures, with loss of viability and morphological changes. Through cross-complementation assays it has been shown that their physiological roles are to some extent redundant. The rhlE mutant also showed reduction in biofilm formation. The relative expression of the genes encoding the RNA helicases showed an increase in the expression of three of these genes under cold stress, and the analysis of the ribosomal profiles showed the possible participation of these three RNA helicases in ribosome biogenesis.
 
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Release Date
2020-02-22
Publishing Date
2018-02-22
 
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