Functional Analysis of the <i>Acinetobacter baumannii</i> XerC and XerD Site-Specific Recombinases: Potential Role in Dissemination of Resistance Genes

• Main Authors: David L. Lin (Author), German M. Traglia (Author), Rachel Baker (Author), David J. Sherratt (Author), Maria Soledad Ramirez (Author), Marcelo E. Tolmasky (Author)
• Format: Book
• Published: MDPI AG, 2020-07-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in <i>Acinetobacter baumannii</i>, are thought to behave as elements that facilitate horizontal dissemination. The <i>A. baumannii</i> <i>xerC</i> and <i>xerD</i> genes were cloned, and the recombinant clones used to complement the cognate <i>Escherichia coli</i> mutants. The complemented strains supported the resolution of plasmid dimers, and, as is the case with <i>E. coli</i> and <i>Klebsiella pneumoniae</i> plasmids, the activity was enhanced when the cells were grown in a low osmolarity growth medium. Binding experiments showed that the partially purified <i>A. baumannii</i> XerC and XerD proteins (XerC_Ab and XerD_Ab) bound synthetic Xer site-specific recombination sites, some of them with a nucleotide sequence deduced from existing <i>A. baumannii</i> plasmids. Incubation with suicide substrates resulted in the covalent attachment of DNA to a recombinase, probably XerC_Ab, indicating that the first step in the recombination reaction took place. The results described show that XerC_Ab and XerD_Ab are functional proteins and support the hypothesis that they participate in horizontal dissemination of resistant genes among bacteria.

Item Description

10.3390/antibiotics9070405
2079-6382