Integrative and Conjugative Elements of SXT/R391 family in Proteus mirabilis clinical isolates and its relationship with resistance, mutagenesis and conjugation.

Author(s)

Juliana Lumi Sato

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2021-11-04

Examining board members

Rodrigo da Silva Galhardo; Regina Lúcia Baldini; Gabriel Padilla Maldonado; Luciene Andrade da Rocha Minarini

• Advisor: Rodrigo da Silva Galhardo

Abstract

Proteus mirabilis is a bacterium that causes catheter-associated urinary-tract infections that frequently carries integrative and conjugative elements (ICEs) of the SXT/R391 family integrated in its chromosome. These elements can carry resistance genes in its variable regions, and encode for its own conjugative transfer complex, and other putative genes with uncharacterized functions or not essential for the transfer mechanism. Among conserved genes there is rumAB that encode a family Y polymerase, which has translesion activity characterized by high error rates. The regulation of those genes encoded by ICEs (genes related to the conjugative process, and also rumAB) is under control of SOS response. The SOS response is activated by damaged DNA caused by multiple genotoxic agents such as UV light and some antimicrobial agents. Due to the induction of translesion polymerases, the SOS response leads to a transiently increased mutation rate that can result in resistance to some antibiotics. In the P. mirabilis genome there is no other homologs of the main bacterial translesion polymerase (PolV), unless when an SXT/R391 family ICE that bears rumAB is present. In this project, in addition to the genomic characterization of these elements in Brazilian clinical isolates of P. mirabilis, we did a functional analysis of the translesion polymerase rumAB in processes such as mutagenesis and conjugative transfer. The isolates bearing an ICE SXT/R391 had their whole genome sequenced to be analyzed in terms of resistance genes carried by those ICEs, and other features carried by them, and to perform phylogenetic analysis comparing them to the other ICEs and genomes in database. Furthermore, the rumAB operon of each isolate was cloned in a plasmid to evaluate the complementation capacity of an E. coli strain devoid of umuDC, and we observed a full complementation of the induced mutagenesis. We also evaluated the same ICE in different isogenic lineages, and we observed different effects in the induced mutagenesis among different lineages, suggesting that the genetic background has some impact on the mutagenic activity. Regarding the role of rumAB in the conjugative transfer, we observed that the operon has influence on the conjugation efficiency, especially when donor cells are exposed to UV light, reinforcing the idea that conserved Pol V in mobile genetic elements has a considerable role in dissemination of these elements in addition to conferring mutagenic capacities through SOS response. (AU)

• FAPESP's process: 18/23872-7 - Integrative conjugative elements of SXT/R391 family in Proteus mirabilis and its correlation with resistance, mutagenesis and conjugation
• Grantee: Juliana Lumi Sato
• Support Opportunities: Scholarships in Brazil - Master