AUTHOR=Wang Shasha , Jiang Kai , Du Xinyue , Lu Yanli , Liao Lijun , He Zhiying , He Weizhi 

TITLE=Translational Attenuation Mechanism of ErmB Induction by Erythromycin Is Dependent on Two Leader Peptides

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.690744

DOI=10.3389/fmicb.2021.690744

ISSN=1664-302X

ABSTRACT=<p>Ribosome stalling on <italic>ermBL</italic> at the tenth codon (Asp) is believed to be a major mechanism of <italic>ermB</italic> induction by erythromycin (Ery). In this study, we demonstrated that the mechanism of <italic>ermB</italic> induction by Ery depends not only on <italic>ermBL</italic> expression but also on previously unreported <italic>ermBL2</italic> expression. Introducing premature termination codons in <italic>ermBL</italic>, we proved that translation of the N-terminal region of <italic>ermBL</italic> is the key component for <italic>ermB</italic> induced by Ery, whereas translation of the C-terminal region of <italic>ermBL</italic> did not affect Ery-induced <italic>ermB</italic>. Mutation of the tenth codon (Asp10) of <italic>ermBL</italic> with other amino acids showed that the degree of induction <italic>in vivo</italic> was not completely consistent with the data from <italic>the in vitro</italic> toe printing assay. Alanine-scanning mutagenesis of <italic>ermBL</italic> demonstrated that both N-terminal residues (R7-K11) and the latter part of <italic>ermBL</italic> (K20-K27) are critical for Ery induction of ermB. The frameshifting reporter plasmid showed that a new leader peptide, <italic>ermBL2</italic>, exists in the <italic>ermB</italic> regulatory region. Further, introducing premature termination mutation and alanine-scanning mutagenesis of <italic>ermBL2</italic> demonstrated that the N-terminus of <italic>ermBL2</italic> is essential for induction by Ery. Therefore, the detailed function of <italic>ermBL2</italic> requires further study.</p>