Response regulator protein CiaR regulates the transcription of ccn-microRNAs and β-lactam antibiotic resistance conversion of Streptococcus pneumoniae

Mei-Juan Yang; Meng-Jie Li; Li-Dan Huang; Xin-Wei Zhang; Yan-Ying Huang; Xiao-Yu Gou; Sui-Ning Chen; Jie Yan; Peng Du; Ai-Hua Sun

doi:10.1016/j.ijantimicag.2024.107387

Response regulator protein CiaR regulates the transcription of ccn-microRNAs and β-lactam antibiotic resistance conversion of Streptococcus pneumoniae

Int J Antimicrob Agents. 2024 Nov 18:107387. doi: 10.1016/j.ijantimicag.2024.107387. Online ahead of print.

Authors

Mei-Juan Yang¹, Meng-Jie Li², Li-Dan Huang³, Xin-Wei Zhang⁴, Yan-Ying Huang⁵, Xiao-Yu Gou⁶, Sui-Ning Chen⁷, Jie Yan⁸, Peng Du⁹, Ai-Hua Sun¹⁰

Affiliations

¹ School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China; The First Hospital of Putian City, Putian Fujian 351100, P.R. China. Electronic address: 2571024049@qq.com.
² School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China. Electronic address: 1983109331@qq.com.
³ School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China; Yiwu Central Blood Station, Yiwu, Zhejiang 322000, P.R. China. Electronic address: 2321528566@qq.com.
⁴ The First Affiliated Hospital of Henan University, Kaifeng Henan 475000, P.R. China. Electronic address: yxjyzxw@163.com.
⁵ Hangzhou Red Cross Hospital, Hangzhou Zhejiang 310003, P.R. China. Electronic address: 1842725667@qq.com.
⁶ School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China. Electronic address: 540600737@qq.com.
⁷ School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China. Electronic address: 249099912@qq.com.
⁸ Zhejiang Provincial Society for Microbiology, Hangzhou, Zhejiang 310058, P.R. China. Electronic address: jieyan19561111@163.com.
⁹ School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China. Electronic address: pdu1145@hmc.edu.cn.
¹⁰ School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang 310053, P.R. China. Electronic address: aihuasun@126.com.

PMID: 39566648
DOI: 10.1016/j.ijantimicag.2024.107387

Abstract

Introduction: Streptococcus pneumoniae does not produce β-lactamases and its reduced susceptibility to β-lactam antibiotics is predominantly caused by mutations of penicillin-binding proteins (PBPs), but mechanisms of PBP mutation-unrelated β-lactam antibiotic resistance in pneumococcal strains remain poorly characterized.

Methods: Susceptibility of S. pneumoniae ATCC49619 and its ciaR gene-knockout, -complemented, or -over-expression mutant (ΔciaR, CΔciaR, or ciaR^OE) to penicillin, cefotaxime, and imipenem was detected using E-test. Levels of pneumococcal ciaR-mRNA, five ccn-microRNAs, and six pbps-mRNAs were determined by qRT-PCR. Recombinant CiaR (rCiaR) binding to the promoters of ccn-microRNA genes was confirmed using electrophoresis mobility shift and chromatin immunoprecipitation assays. Sequence matching between the ccn-microRNAs and pbps-mRNAs were analyzed using IntaRNA software.

Results: S. pneumoniae ATCC49619 was sensitive to the three β-lactam antibiotics, but over-expression of CiaR, a response regulator protein in two-component system, caused the increase of MICs against these antibiotics. The ciaR^OE mutant exhibited the significantly increased transcription of ccn-microRNAs but notably decreased transcription of pbps-mRNAs, conversely the ΔciaR mutant displayed decreased levels of ccn-microRNAs and increasesed transcription of pbps-mRNAs. rCiaR could bind to the promoters of all ccn-microRNA genes in vitro and within cells. The three antibiotics at 1/8 minimal inhibitory concentrations caused a significant increase in the ciaR-mRNA and ccn-microRNAs. The mRNA-binding seed sequences in the five ccn-microRNAs matched all the promoter-containing sequences of pbps-mRNAs.

Conclusions: β-lactam antibiotics at low-concentrations induce PBP mutation-unrelated antibiotic resistance conversion of S. pneumoniae by decrease of PBPs through pathway of CiaR-mediated transcriptional increase of ccn-microRNAs and ccn-microRNA-dependent degradation of pbp-mRNAs.

Keywords: CiaR, Pneumococcal microRNAs, Penicillin-binding proteins, EMSA, ChIP, β-lactam antibiotics; Resistance; Streptococcus pneumoniae, Response regulator protein.