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Master's Dissertation
DOI
https://doi.org/10.11606/D.42.2018.tde-25092018-172141
Document
Author
Full name
Alexy Orozco Valencia
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Galhardo, Rodrigo da Silva (President)
Barros, Mário Henrique de
Gueiros Filho, Frederico José
Lage, Claudia de Alencar Santos
Title in Portuguese
O papel das DNA polimerases propensas a erro e da atividade das uracila DNA glicosilases na mutagênese espontânea em Caulobacter crescentus.
Keywords in Portuguese
C. crescentus
DNA polimerases
Mutagênese espontânea
Abstract in Portuguese
Neste trabalho desvendamos o papel das DNA polimerases dinB e dnaE2 em C. crescentus na mutagênese espontânea usando dois marcadores moleculares xylbla e CItet. Observamos que as taxas de mutação dos marcadores não variam significativamente entre dinB, dnaE2 e parental, coincidindo com os resultados prévios com o gene rpoB. As trocas de bases, tanto no gene cI, como em xylR, há um predomínio de mutações ATCG, como observado em rpoB, e diferente da região PxylX em xylbla. O gene xylR apresenta um hotspot que promove a inserção de uma citosina após a base 230. Neste marcador observamos que a presença de pequenas deleções (frameshifts-1) de uma base na cepa selvagem e dnaE2. Esse tipo de mutação não está presente na linhagem dinB. Esses resultados sugerem um papel importante de dinB na formação de deleções (frameshifts-1) in vivo em C. crescentus. Também observou-se que o agente 4-NQO não induz mutagênese em C. crescentus, ao contrário de E. coli. Também observamos pouca eficiência da atividade de uracila glicosilase em C. crescentus quando comparada com E. coli.
Title in English
The role of error-prone DNA polymerases and the activity of uracil DNA glycosylases on spontaneous mutagenesis in Caulobacter crescentus.
Keywords in English
C. crescentus
DNA polymerases
Spontaneous mutagenesis
Abstract in English
In this work we analyzed the role of DNA polymerases dinB and dnaE2 in spontaneous mutagenesis in C. crescentus, using two molecular markers: xylbla and Cltet. Our studies show that there is no significant difference in mutation rates in both markers between dinB, dnaE2 and wild type; this agrees with previous results using rpoB gene. Here, we report that there is a predominance of ATGC transitions in either cl gene or xylR, which was also shown in rpoB; however, this differs in PxylX region of xylbla. We also observed that xylR presents a mutation hotspot that promotes cytosine insertion after base 230.The presence of small one-base deletions (frameshifts-1) in wild typecbut ells, this type of mutation does not occur in the dinB strain. These results suggest an important role for dinB in the formation of deletions (frameshifts-1) in vivo in C. crescentus. We also saw that 4-NQO agent does not induce mutagenesis in C. crescentus, as it does in E. coli. Finally, the results demonstrate a poor efficiency in UDG activity in C. crescentus, when compared to E. coli.
 
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Release Date
2020-09-24
Publishing Date
2018-09-25
 
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