Thioredoxin Reductase Is Essential for Protection ofNeisseria gonorrhoeaeagainst Killing by Nitric Oxide and for Bacterial Growth during Interaction with Cervical Epithelial Cells

Abstract

In Neisseria gonorrhoeae, the MerR family transcription factor NmlR activates 3 operons in response to disulfide stress. In the present study, we show that trxB, a monocistronic operon under the control of NmlR, encodes a functional thioredoxin reductase. It is shown that neisserial TrxB has biochemical properties similar to those of its homologue from Escherichia coli. Analysis of a trxB mutant of N. gonorrhoeae showed that it was more sensitive to disulfide stress and to stress induced by organic hydroperoxides, superoxide, and nitric oxide than wild-type gonococcus. TrxB was found to be essential for the microaerobic induction of aniA and norB, the genes encoding nitrite reductase and nitric oxide reductase, respectively. The importance of TrxB during natural infection was demonstrated by the fact that the survival of gonococci within human cervical epithelial cells, as well as biofilm formation on these cells, was greatly reduced for a trxB mutant compared with a wild-type strain.

Phenotypic Characterization of acopAMutant of Neisseria gonorrhoeae Identifies a Link between Copper and Nitrosative Stress

“…In earlier publications, we also showed that mutation of estD and trxB resulted in a greatly diminished ability of N. gonorrhoeae to form biofilms both on glass and over THCECs (20,21). Therefore, we evaluated biofilm formation by wild-type 1291 and 1291 copA after 2 days of growth under continuous flow (Table 1; see Fig.…”

“…In women, gonococci are typ-ically associated with the cervical epithelium and are able to invade, survive, and replicate within these cells (4). We previously reported that inactivation of estD and trxB, two genes in the NmlR regulon, results in reduced survival of N. gonorrhoeae during challenge of cervical epithelial cells (20,21). To determine if copA is also important during cervical infection, we tested the ability of N. gonorrhoeae 1291 and 1291 copA to associate with, invade, and survive within pex cells.…”

“…NmlR controls the expression of a small regulon comprised of nmlR itself (NGO0602), adhC-estD (NGO0601-NGO0600, encoding an alcohol dehydrogenase pseudogene and a thioesterase gene, respectively), trxB (NGO0580, encoding thioredoxin reductase), and copA (NGO0579, encoding a putative cationtransporting ATPase). In subsequent studies, we showed that a trxB mutant was sensitive to killing by NO, whereas an estD mutant was sensitive to killing by S-nitrosoglutathione (GSNO) and was unable to grow in liquid cultures in the presence of nitrite (20,21). Both mutants showed reduced abilities to form a biofilm on transformed human cervical epithelial cells (THCECs) and also to invade and survive within primary cervical epithelial (pex) cells.…”

Bordetella pertussis Adenylate Cyclase Toxin Blocks Induction of Bactericidal Nitric Oxide in Macrophages through cAMP-Dependent Activation of the SHP-1 Phosphatase

“…2B, indeed, B. pertussis is rather susceptible to NO-mediated killing in vitro, because exposure to 400 mM DEANONOate as a donor of NO radicals (35,36) significantly decreased viability of the bacteria, albeit less than upon oxidative killing by 100 mM H 2 O 2 (37). As further shown in Fig.…”

Nitric Oxide: A Key Mediator of Biofilm Dispersal with Applications in Infectious Diseases

“…For instance addition of NO donors was shown to induce dispersal in biofilms of P. [45] and a marine Pseudoalteromonas species [46], and in Vibrio fischeri addition of a NO scavenger prevented dispersal of aggregates [47]. Exposure to nitrite inhibited biofilm formation by Staphylococcus aureus, presumably through generating NO and inducing dispersal [48].…”