(Public Library of Science, 2013) Ruiz de los Mozos Aliaga, Igor; Vergara Irigaray, Marta; Segura, Víctor; Villanueva San Martín, Maite; Bitarte Manzanal, Nerea; Saramago, Margarida; Domingues, Susana; Arraiano, Cecilia M.; Fechter, Pierre; Romby, Pascale; Valle Turrillas, Jaione; Solano Goñi, Cristina; Lasa Uzcudun, Íñigo; Toledo Arana, Alejandro; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
The presence of regulatory sequences in the 39 untranslated region (39-UTR) of eukaryotic mRNAs controlling RNA stability
and translation efficiency is widely recognized. In contrast, the relevance of 39-UTRs in bacterial mRNA functionality has
been disregarded. Here, we report evidences showing that around one-third of the mapped mRNAs of the major human
pathogen Staphylococcus aureus carry 39-UTRs longer than 100-nt and thus, potential regulatory functions. We selected the
long 39-UTR of icaR, which codes for the repressor of the main exopolysaccharidic compound of the S. aureus biofilm matrix,
to evaluate the role that 39-UTRs may play in controlling mRNA expression. We showed that base pairing between the 39-
UTR and the Shine-Dalgarno (SD) region of icaR mRNA interferes with the translation initiation complex and generates a
double-stranded substrate for RNase III. Deletion or substitution of the motif (UCCCCUG) within icaR 39-UTR was sufficient to
abolish this interaction and resulted in the accumulation of IcaR repressor and inhibition of biofilm development. Our
findings provide a singular example of a new potential post-transcriptional regulatory mechanism to modulate bacterial
gene expression through the interaction of a 39-UTR with the 59-UTR of the same mRNA.
