Regulation of neutrophil myeloperoxidase inhibitor SPIN by the small RNA Teg49 in Staphylococcus aureus

• Published in: Molecular microbiology Vol. 117; no. 6; pp. 1447 - 1463
• Main Authors: Cengher, Liviu, Manna, Adhar C., Cho, Junho, Theprungsirikul, Jomkuan, Sessions, Katherine, Rigby, William, Cheung, Ambrose L.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-06-2022
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding sites; Catalytic activity; gene expression; Gene Expression Regulation, Bacterial - genetics; human neutrophils; Humans; Leukocytes (neutrophilic); Mutants; Mutation; myeloperoxidase; Neutrophils; Peroxidase; Peroxidase - genetics; Peroxidase - metabolism; Phagocytosis; regulatory small RNA; Residues; Ribonucleic acid; RNA; RNA, Messenger - metabolism; RNA, Small Untranslated - genetics; RNA, Small Untranslated - metabolism; SPIN; spn; Staphylococcal Infections; Staphylococcus aureus; Staphylococcus aureus - genetics; Staphylococcus aureus - metabolism; virulence; spn; regulatory small RNA; RNA; SPIN; virulence; myeloperoxidase; Staphylococcus aureus; gene expression; human neutrophils
• DOI: 10.1111/mmi.14919
• EISSN: 1365-2958
• ISSN: 0950-382X

Teg49 is a Staphylococcus aureus trans‐acting regulatory sRNA derived from cleavage of the sarA P3 transcript. We showed by RNA‐Seq here that the 5′ trident‐like structure in Teg49 regulates transcriptionally (direct and indirect) 22 genes distinct from sarA. Among these, Teg49 was noted to repress spn, encoding a 102 residue preprotein which yields the mature 73 residue peptide which inhibits the catalytic activity of myeloperoxidase in human neutrophils. Teg49 was found to regulate spn mRNA post‐transcriptionally in strain SH1000 through 9‐nt base‐pairing between hairpin loop 2 of Teg49 and an exposed bulge of the spn mRNA. Mutations of the Teg49 binding site disrupted the repression of spn, leading to reduced degradation, and increased half‐life of spn mRNA in the Teg49 mutant. The spn‐Teg49 interaction was also confirmed with a synonymous spn mutation to yield enhanced spn expression in the mutant vs. the parent. The Teg49 mutant with increased spn expression exhibited enhanced resistance to MPO activity in vitro. Killing assays with human neutrophils showed that the Teg49 mutant was more resistant to killing after phagocytosis. Altogether, this study shows that Teg49 in S. aureus has a distinct and important regulatory profile whereby this sRNA modulates resistance to myeloperoxidase‐mediated killing by human neutrophils.
In Staphylococcus aureus, Teg49 is a trans‐acting regulatory sRNA located in the 5′ UTR of the sarA mRNA, which encodes a DNA binding protein that regulates key virulence pathways. In this study, we showed that Teg49 regulates genes distinct from SarA. Using mutagenesis and phenotypic assays, we discovered that Teg49 regulates virulence by degrading the mRNA of SPIN, a myeloperoxidase inhibitor that hinders neutrophil killing of S. aureus in the phagolysosome.