AUTHOR=Lallement Claire , Pasternak Cécile , Ploy Marie-Cécile , Jové Thomas 

TITLE=The Role of ISCR1-Borne POUT Promoters in the Expression of Antibiotic Resistance Genes

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02579

DOI=10.3389/fmicb.2018.02579

ISSN=1664-302X

ABSTRACT=<p>The IS<italic>CR1</italic> (Insertion sequence Common Region) element is the most widespread member of the IS<italic>CR</italic> family, and is frequently present within γ-proteobacteria that occur in clinical settings. IS<italic>CR1</italic> is always associated with the 3′Conserved Segment (3′CS) of class 1 integrons. IS<italic>CR1</italic> contains outward-oriented promoters P<sub>OUT</sub>, that may contribute to the expression of downstream genes. In IS<italic>CR1</italic>, there are two P<sub>OUT</sub> promoters named P<sub>CR1-1</sub> and P<sub>CR1-2</sub>. We performed an <italic>in silico</italic> analysis of all publically available IS<italic>CR1</italic> sequences and identified numerous downstream genes that mainly encode antibiotic resistance genes and that are oriented in the same direction as the P<sub>OUT</sub> promoters. Here, we showed that both P<sub>CR1-1</sub> and P<sub>CR1-2</sub> significantly increase the expression of the downstream genes <italic>bla</italic><sub>CTX-M-9</sub> and <italic>dfrA19</italic>. Our data highlight the role of IS<italic>CR1</italic> in the expression of antibiotic resistance genes, which may explain why IS<italic>CR1</italic> is so frequent in clinical settings.</p>