The Mla Pathway Plays an Essential Role in the Intrinsic Resistance of Burkholderia cepacia Complex Species to Antimicrobials and Host Innate Components
The Mla Pathway Plays an Essential Role in the Intrinsic Resistance of Burkholderia cepacia Complex Species to Antimicrobials and Host Innate Components
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DOI：
10.1128/jb.00156-18
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发表时间：
2018-09-01
影响因子：
3.2
通讯作者：
Surette, Michael G.
中科院分区：
文献类型：
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作者：
Bernier, Steve P.;Son, Susie;Surette, Michael G.
抗生素耐药性对我们的现代社会构成威胁，需要新的策略来识别新分子或靶点来对抗多重耐药病原体。伯克霍尔德杆菌属的物种，包括洋葱伯克霍尔德杆菌复合体（Bcc）、类鼻疽伯克霍尔德杆菌和鼻疽伯克霍尔德杆菌，可能具有高致病性，并且对多种抗生素具有内在耐药性。尽管如此，Bcc 物种对铜绿假单胞菌在种间竞争中释放的细胞外产物敏感。我们筛选了对铜绿假单胞菌废培养基敏感性增加的伯克霍尔德杆菌转座子突变体，并鉴定了与 Mla 途径具有同源性的基因中的多个突变体。 Bcc Mla 途径的代表性基因中的插入突变体的细胞膜受损，并且对各种细胞外应激（包括抗生素和人血清）更加敏感。更准确地说，Bcc 物种新洋葱伯克霍尔德菌和多洛萨伯克霍尔德菌的 mla 突变体对革兰氏阳性抗生素（即大环内酯类和利福平）、氟喹诺酮类、四环素类和氯霉素更敏感。 mlaC 插入突变体的基因互补恢复了细胞通透性和对革兰氏阳性抗生素的耐药性。重要的是，Bcc mla 突变体并非普遍较弱的菌株，因为它们对其他类别抗生素的敏感性不受影响。尽管大肠杆菌或铜绿假单胞菌中同源mla突变体的细胞通透性也受损，但它们并不像在Bcc mla突变体中观察到的那样对革兰氏阳性抗生素或其他抗菌剂更敏感。总之，数据表明，伯克霍尔德杆菌中的 Mla 途径可能发挥不同的生物学作用，这可能代表伯克霍尔德杆菌与抗生素佐剂联合治疗中的特定药物靶点。 重要性 革兰氏阴性细菌的外膜可作为有毒化合物的有效屏障，因此损害这种结构可能会增加对现有抗生素的敏感性。在这项研究中，我们表明，与其他变形菌相比，洋葱伯克霍尔德菌复合体物种中的 Mla 途径（一个涉及维持外膜完整性的系统）在遗传和功能上都存在差异。新洋葱伯克霍尔德菌或多洛萨伯克霍尔德菌的 mla 基因突变体对革兰氏阳性抗生素敏感，而在大肠杆菌或铜绿假单胞菌中未观察到这种效应。伯克霍尔德杆菌属物种中的 Mla 途径可能代表解决其固有抗菌药物耐药性的理想属特异性靶标。
Antibiotic resistance is a threat to our modern society and new strategies leading to the identification of new molecules or targets to combat multidrug-resistant pathogens are needed. Species of the genus Burkholderia, including Burkholderia cepacia complex (Bcc), Burkholderia pseudomallei, and Burkholderia mallei can be highly pathogenic and are intrinsically resistant to multiple classes of antibiotics. Bcc species are nonetheless sensitive to extracellular products released by Pseudomonas aeruginosa in interspecies competition. We screened for Burkholderia transposon mutants with increased sensitivity to P. aeruginosa spent medium and identified multiple mutants in genes sharing homology with the Mla pathway. Insertional mutants in representative genes of the Bcc Mla pathway had a compromised cell membrane and were more sensitive to various extracellular stresses, including antibiotics and human serum. More precisely, mla mutants in the Bcc species Burkholderia cenocepacia and Burkholderia dolosa were more susceptible to Gram-positive antibiotics (i.e. macrolides and rifampicin), fluoroquinolones, tetracyclines, and chloramphenicol. Genetic complementation of mlaC insertional mutants restored cell permeability and resistance to Gram-positive antibiotics. Importantly, Bcc mla mutants were not universally weaker strains since their susceptibilities to other classes of antibiotics were unaffected. Although cell permeability of homologous mla mutants in Escherichia coli or P. aeruginosa was also impaired, they were not more sensitive to Gram-positive antibiotics or other antimicrobials as was observed in Bcc mla mutants. Together, the data suggest that the Mla pathway in Burkholderia may play a different biological role, which could potentially represent a Burkholderia-specific drug target in combination therapy with antibiotic adjuvants.Importance The outer membrane of Gram-negative bacteria acts as an effective barrier against toxic compounds, therefore compromising this structure could increase sensitivity to currently available antibiotics. In this study, we show that the Mla pathway, a system involved in maintaining the integrity of the outer membrane, is genetically and functionally different in Burkholderia cepacia complex species compared to other proteobacteria. Mutants in mla genes of Burkholderia cenocepacia or Burkholderia dolosa were sensitive to Gram-positive antibiotics, while this effect was not observed in Escherichia coli or Pseudomonas aeruginosa. The Mla pathway in Burkholderia species may represent an ideal genus-specific target to address their intrinsic antimicrobial resistances.