Sodium Ion Cycle in Bacterial Pathogens: Evidence from Cross-Genome Comparisons

Abstract

Analysis of the bacterial genome sequences shows that many human and animal pathogens encode primary membrane Na+ pumps, Na+-transporting dicarboxylate decarboxylases or Na+-translocating NADH:ubiquinone oxidoreductase, and a number of Na+-dependent permeases. This indicates that these bacteria can utilize Na+ as a coupling ion instead of or in addition to the H+ cycle. This capability to use a Na+ cycle might be an important virulence factor for such pathogens as Vibrio cholerae, Neisseria meningitidis, Salmonella enterica serovar Typhi, and Yersinia pestis. In Treponema pallidum, Chlamydia trachomatis, and Chlamydia pneumoniae, the Na+ gradient may well be the only energy source for secondary transport. A survey of preliminary genome sequences of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, and Treponema denticola indicates that these oral pathogens also rely on the Na+ cycle for at least part of their energy metabolism. The possible roles of the Na+ cycling in the energy metabolism and pathogenicity of these organisms are reviewed. The recent discovery of an effective natural antibiotic, korormicin, targeted against the Na+-translocating NADH:ubiquinone oxidoreductase, suggests a potential use of Na+ pumps as drug targets and/or vaccine candidates. The antimicrobial potential of other inhibitors of the Na+ cycle, such as monensin, Li+ and Ag+ ions, and amiloride derivatives, is discussed

Bacterial diversity and activity along a salinity gradient in soda lakes of the Kulunda Steppe (Altai, Russia)

“…It is possible that preferential amplification of the DNA template from low G + C content occurred due to the easier dissociation into single DNA strand than higher G + C templates, resulting in a bias in the favor of the former group (Suzuki and Giovannoni 1996). On the other hand, it could also be that low G + C bacteria, like acetogenic clostridia, out-number SRB at hypersaline alkaline conditions, since it is known that the acetogenic haloalkaliphiles benefit from sodium-based energetics (Häse et al 2001). This was also observed by DGGE analysis and microscopic analysis of the highest positive tubes of the serial dilutions in SRB media, which revealed the predominance of Clostridia even at the highest dilutions.…”

The genome sequence of Clostridium tetani , the causative agent of tetanus disease

“…Furthermore, the genes for a membrane-bound electron transport chain could be identified in the genomes of C. tetani and C. perfringens. This system shows strong similarity to the Rhodobacter-specific nitrogen fixation system of Rhodobacter capsulatus as well as to the system NADH:ubiquinone oxidoreductase found in many aerobic pathogens such as V. cholerae, Salmonella typhimurium, Y. pestis, and Haemophilus influenzae, in which it apparently functions as a Na ϩ -translocating NADH dehydrogenase (32,36). Because there are no reports for quinones in clostridia, such a NADH dehydrogenase could be involved in the fermentation of amino acids by C. tetani, as indicated in Fig.…”

Proteomic aspects of Parachlamydia acanthamoebae infection in Acanthamoeba spp.

“…Thus, at present, it is not possible to make any conclusive predictions with regard to this protein's expression level. Still, as NADHubiquinone oxidoreductase has been suggested to be indicative of bacterial virulence (Häse et al, 2001) and as the exploitation of Na þ gradients in energy metabolism has been suggested to be a widespread strategy among human pathogens, including C. pneumoniae and C. trachomatis (Häse et al, 2001), the potentially very high expression of this enzyme in P. acanthamoebae warrants further investigation.…”