title: Structure and function of CinD (YtjD) of Lactococcus lactis, a copper-induced nitroreductase involved in defense against oxidative stress.
abstract: In Lactococcus lactis IL1403, 14 genes are under the control of the copper-inducible CopR repressor. This so-called CopR regulon encompasses the CopR regulator, two putative CPx-type copper ATPases, a copper chaperone, and 10 additional genes of unknown function. We addressed here the function of one of these genes, ytjD, which we renamed cinD (copper-induced nitroreductase). Copper, cadmium, and silver induced cinD in vivo, as shown by real-time quantitative PCR. A knockout mutant of cinD was more sensitive to oxidative stress exerted by 4-nitroquinoline-N-oxide and copper. Purified CinD is a flavoprotein and reduced 2,6-dichlorophenolindophenol and 4-nitroquinoline-N-oxide with k(cat) values of 27 and 11 s(-1), respectively, using NADH as a reductant. CinD also exhibited significant catalase activity in vitro. The X-ray structure of CinD was resolved at 1.35 A and resembles those of other nitroreductases. CinD is thus a nitroreductase which can protect L. lactis against oxidative stress that could be exerted by nitroaromatic compounds and copper.
authors.affiliation: Department of Clinical Pharmacology and Visceral Research, University of Berne, Berne, Switzerland.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Mermod
authors.forename: Frédéric
authors.initials: F
authors.lastname: Mourlane
authors.forename: Sandro
authors.initials: S
authors.lastname: Waltersperger
authors.forename: Anselm E
authors.initials: AE
authors.lastname: Oberholzer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Baumann
authors.forename: Marc
authors.initials: M
authors.lastname: Solioz
mesh_terms: D015086:2,6-Dichloroindophenol / Q000378:metabolism; D015112:4-Nitroquinoline-1-oxide / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism; D002374:Catalase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005420:Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D007700:Kinetics; D013294:Lactococcus lactis / Q000201:enzymology* / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D009601:Nitroreductases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012834:Silver / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D005420:Flavoproteins; D016877:Oxidants; D002104:Cadmium; D009243:NAD; D012834:Silver; D015112:4-Nitroquinoline-1-oxide; D003300:Copper; D015086:2,6-Dichloroindophenol; D002374:Catalase; D009601:Nitroreductases