Purine nucleosides interfere with c-di-AMP levels and act as adjuvants to re-sensitise MRSA to β-lactam antibiotics

Author:

Nolan Aaron C.,Zeden Merve S.ORCID,Campbell Christopher,Kviatkovski Igor,Urwin Lucy,Corrigan Rebecca M.ORCID,Gründling AngelikaORCID,O’Gara James P.ORCID

Abstract

AbstractElucidating the complex mechanisms controlling mecA/PBP2a-mediated β-lactam resistance in methicillin resistant Staphylococcus aureus (MRSA) has the potential to identify new drug targets with therapeutic potential. Here, we report that mutations that interfere with de novo purine synthesis (pur operon), purine transport (NupG, PbuG and PbuX) and the nucleotide salvage pathway (DeoD2, Hpt) increased β-lactam resistance in MRSA strain JE2. Extrapolating from these findings, exogenous guanosine and xanthosine, which are fluxed through the GTP branch of purine biosynthesis were shown to significantly reduce MRSA β-lactam resistance. In contrast adenosine, which is fluxed to ATP, significantly increased oxacillin resistance, whereas inosine, which can be fluxed to ATP and GTP via hypoxanthine, only marginally reduced the oxacillin MIC. Increased oxacillin resistance of the nupG mutant was not significantly reversed by guanosine, indicating that NupG is required for guanosine transport, which in turn is required to reduce β-lactam resistance. Suppressor mutants resistant to oxacillin/guanosine combinations contained several purine salvage pathway mutations, including nupG and hpt. Microscopic analysis revealed that guanosine significantly increased cell size, a phenotype also associated with reduced levels of c-di-AMP. Consistent with this, guanosine significantly reduced levels of c-di-AMP, and inactivation of GdpP, the c-di-AMP phosphodiesterase negated the impact of guanosine on β-lactam susceptibility. PBP2a expression was unaffected in nupG or deoD2 mutants suggesting that guanosine-induced β-lactam susceptibility may result from dysfunctional c-di-AMP-dependent osmoregulation. These data reveal the therapeutic potential of purine nucleosides as β-lactam adjuvants that interfere with the normal activation of c-di-AMP required for high-level β-lactam resistance in MRSA.ImportanceThe clinical burden of infections caused by antimicrobial resistant (AMR) pathogens is a leading threat to public health. Maintaining the effectiveness of existing antimicrobial drugs or finding ways to reintroduce drugs to which resistance is widespread is an important part of efforts to address the AMR crisis. Predominantly the safest and most effective class of antibiotics are the β-lactams, which are no longer effective against methicillin resistant Staphylococcus aureus (MRSA). Here we report that the purine nucleosides guanosine and xanthosine have potent activity as adjuvants that can resensitise MRSA to oxacillin and other β-lactam antibiotics. Mechanistically, exposure of MRSA to these nucleosides significantly reduced the levels of the cyclic dinucleotide c-di-AMP, which is required for β-lactam resistance. Drugs derived from nucleotides are widely used in the treatment of cancer and viral infections highlighting the clinical potential of using purine nucleosides to restore or enhance the therapeutic effectiveness of β-lactams against MRSA and potentially other AMR pathogens.

Publisher

Cold Spring Harbor Laboratory

Cited by 1 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3