Transgenesis of mammalian PABP reveals mRNA polyadenylation as a general stress response mechanism in bacteria

Nimmy Francis; Rakesh S Laishram

doi:10.1016/j.isci.2021.103119

Transgenesis of mammalian PABP reveals mRNA polyadenylation as a general stress response mechanism in bacteria

iScience. 2021 Sep 11;24(10):103119. doi: 10.1016/j.isci.2021.103119. eCollection 2021 Oct 22.

Authors

Nimmy Francis^{1

2}, Rakesh S Laishram¹

Affiliations

¹ Cardiovascular and Diabetes Biology Group, Rajiv Gandhi Centre for Biotechnology, Thycaud Post, Poojappura, Trivandrum 695014, India.
² Manipal Academy of Higher Education, Manipal 576104, India.

Abstract

In eukaryotes, mRNA 3'-polyadenylation triggers poly(A) binding protein (PABP) recruitment and stabilization. In a stark contrast, polyadenylation marks mRNAs for degradation in bacteria. To study this difference, we trans-express the mammalian nuclear PABPN1 chromosomally and extra-chromosomally in Escherichia coli. Expression of PABPN1 but not the mutant PABPN1 stabilizes polyadenylated mRNAs and improves their half-lives. In the presence of PABPN1, 3'-exonuclease PNPase is not detected on PA-tailed mRNAs compromising the degradation. We show that PABPN1 trans-expression phenocopies pcnB (that encodes poly(A) polymerase, PAPI) mutation and regulates plasmid copy number. Genome-wide RNA-seq analysis shows a general up-regulation of polyadenylated mRNAs on PABPN1 expression, the largest subset of which are those involved in general stress response. However, major global stress regulators are unaffected on PABPN1 expression. Concomitantly, PABPN1 expression or pcnB mutation imparts cellular tolerance to multiple stresses. This study establishes mRNA 3'-polyadenylation as a general stress response mechanism in E. coli.

Keywords: Bacteriology; Microbiology; Molecular biology.