The 2-Cys Peroxiredoxin Alkyl Hydroperoxide Reductase C Binds Heme and Participates in Its Intracellular Availability in Streptococcus agalactiae

Abstract

Heme is a redox-reactive molecule with vital and complex roles in bacterial metabolism, survival, and virulence. However, few intracellular heme partners were identified to date and are not well conserved in bacteria. The opportunistic pathogen Streptococcus agalactiae (group B Streptococcus) is a heme auxotroph, which acquires exogenous heme to activate an aerobic respiratory chain. We identified the alkyl hydroperoxide reductase AhpC, a member of the highly conserved thiol-dependent 2-Cys peroxiredoxins, as a heme-binding protein.

Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

“…Other cytoplasmic proteins such as AhpC in S. agalactiae and HutZ in V. cholerae also bind heme (54,127). AhpC is a 2-Cys peroxiredoxin family protein, but its peroxidase activity does not depend on its heme-binding status (54). The mutation of either of these proteins, however, does not result in increased heme sensitivity (54,127).…”

“…Intriguingly, the mechanism for its protection against heme toxicity seems twofold, as both its antioxidant function and heme-binding function were individually able to rescue the heme sensitivity of the sodC mutant (74). Other cytoplasmic proteins such as AhpC in S. agalactiae and HutZ in V. cholerae also bind heme (54,127). AhpC is a 2-Cys peroxiredoxin family protein, but its peroxidase activity does not depend on its heme-binding status (54).…”

Discovery of Intracellular Heme-binding Protein HrtR, Which Controls Heme Efflux by the Conserved HrtB-HrtA Transporter in Lactococcus lactis

“…A 352-bp DNA fragment located in the hrtR-coding region was generated similarly with primers (O19-O20) (supplemental Table 2) and used as a negative control. The palindrome was mutated by using overlapping PCR using primers (O17-O22) and (O21-O18) as described (29). O22 and its reverse counterpart O21 were designed to encompass the 15-nt palindromic sequence and in which the 15 nucleotides were randomly altered to produce the sequence: 5Ј-ATTATATAGAGAGAA-3Ј (instead of 5Ј-ATGACACAGTGTCAT-3Ј) (supplemental Table 2).…”

Isolation of lactic acid bacteria exhibiting high scavenging activity for environmental hydrogen peroxide from fermented foods and its two scavenging enzymes for hydrogen peroxide

“…AhpF and the NADH oxidase belong to the peroxiredoxin reductase family and function as peroxide scavengers, showing an extremely fast reaction rate in spore-forming lactic acid bacteria and related species, such as Sporolactobacillus inulinus (Nishiyama et al, 1997) and Amphibacillus xylanus (Niimura and Massey, 1996;Niimura et al, 1995), which lack a respiratory chain and heme-catalase as do lactic acid bacteria. Accordingly, some lactic acid bacteria must have a highly active hydrogen peroxide scavenging enzyme (Jiang et al, 2005;Lechardeur et al, 2010; To obtain lactic acid bacteria that scavenge environmental hydrogen peroxide, we developed a specialized enrichment medium and successfully isolated Pediococcus pentosaceus Be1 strain from a fermented food. This strain showed vigorous environmental hydrogen peroxide scavenging activity over a wide range of hydrogen peroxide concentrations.…”

“…However, there have been some reports regarding various hydrogen peroxide-degrading intracellular enzymes of lactic acid bacteria (Dolin, 1953;Hanson and Haggstrom, 1984;Mochizuki et al, 2012). Streptococcus mutans, Lactococcus lactis, and S. agalactiae have a two-component peroxide-scavenging system that consists of AhpF (or NADH oxidase) and AhpC (Prx) (Jiang et al, 2005;Lechardeur et al, 2010;Poole et al, 2000). AhpF and the NADH oxidase belong to the peroxiredoxin reductase family and function as peroxide scavengers, showing an extremely fast reaction rate in spore-forming lactic acid bacteria and related species, such as Sporolactobacillus inulinus (Nishiyama et al, 1997) and Amphibacillus xylanus (Niimura and Massey, 1996;Niimura et al, 1995), which lack a respiratory chain and heme-catalase as do lactic acid bacteria.…”