A copper‐induced quinone degradation pathway provides protection against combined copper/quinone stress in Lactococcus lactis IL1403. Issue 4 (30th December 2014)

• Record Type: Journal Article
• Authors: Mancini, Stefano; Abicht, Helge K.; Gonskikh, Yulia; Solioz, Marc
• Is Part Of: Molecular microbiology. Volume 95:Issue 4(2015)
• Page Start: 645
• Page End: 659
• Publication Date: 2014-12-30
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12889
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Quinones are ubiquitous in the environment. They occur naturally but are also in widespread use in human and industrial activities. Quinones alone are relatively benign to bacteria, but in combination with copper, they become toxic by a mechanism that leads to intracellular thiol depletion. Here, it was shown that the <italic>yahCD</italic>‐<italic>yaiAB</italic> operon of <italic>L</italic><italic>actococcus lactis</italic> IL1403 provides resistance to combined copper/quinone stress. The operon is under the control of CopR, which also regulates expression of the <italic>copRZA</italic> copper resistance operon as well as other <italic>L</italic><italic>. lactis</italic> genes. Expression of the <italic>yahCD</italic>‐<italic>yaiAB</italic> operon is induced by copper but not by quinones. Two of the proteins encoded by the operon appear to play key roles in alleviating quinone/copper stress: YaiB is a flavoprotein that converts <italic>p</italic>‐benzoquinones to less toxic hydroquinones, using reduced nicotinamide adenine dinucleotide phosphate (NADPH) as reductant; YaiA is a hydroquinone dioxygenase that converts hydroquinone putatively to 4‐hydroxymuconic semialdehyde in an oxygen‐consuming reaction. Hydroquinone and methylhydroquinone are both substrates of YaiA. Deletion of <italic>yaiB</italic> causes increased sensitivity of <italic>L</italic><italic>. lactis</italic> to quinones and complete growth arrest under combined quinone and copper stress. Copper induction of the <italic>yahCD</italic>‐<italic>yaiAB</italic> operon offers protection to copper/quinone toxicity and could provide a growth advantage to <italic>L</italic><italic>. lactis</italic> in some environments.</p> </abstract>