Carbonic Anhydrase from Porphyromonas Gingivalis as a Drug Target

Abstract

Periodontitis originates from a microbial synergy causing the development of a mouth microbial imbalance (dysbiosis), consisting of a microbial community composed of anaerobic bacteria. Most studies concerning the treatment of periodontitis have primarily take into account the Gram-negative bacterium Porphyromonas gingivalis, because it is a prominent component of the oral microbiome and a successful colonizer of the oral epithelium. Here, we focus our attention on the study of the carbonic anhydrases (CAs, EC 4.2.1.1) encoded in the genome of this pathogen as a possible drug target. Carbonic anhydrases are a superfamily of metalloenzymes, which catalyze the simple but physiologically crucial reaction of carbon dioxide hydration to bicarbonate and protons. Bacterial CAs have attracted significant attention for affecting the survival, invasion, and pathogenicity of many microorganisms. The P. gingivalis genome encodes for two CAs belonging to β-CA (PgiCAβ) and γ-CA (PgiCAγ) families. These two enzymes were cloned, heterologously expressed in Escherichia coli, and purified to homogeneity. Moreover, they were subject to extensive inhibition studies using the classical CA inhibitors (sulfonamides and anions) with the aim of identifying selective inhibitors of PgiCAβ and PgiCAγ to be used as pharmacological tools for P. gingivalis eradication.

Keywords: Porphyromonas gingivalis; anions; antibacterials; antiinfectives; carbonic anhydrases; kinetic constants; periodontitis; sulfonamides.

Figure 1

Structure of the sulfonamides/sulfamates investigated.

Figure 1

Structure of the sulfonamides/sulfamates investigated.

Figure 2

Inhibition of human isoforms hCA I and hCA II, and of the two Porphyromonas gingivalis CAs (PgiCAβ and PgiCAγ) with sulfonamides 1–24 and the clinically used drugs AAZ-HTC for the CO₂ hydration reaction. The figure was generated using the program Prism and excludes all the inhibitors with K_I > 500 nM. The absence of the bar means that the inhibitor exhibits K_I > 500 nM. The errors were in the range of 5–10% of the shown data from three different assays.

Figure 3

Inhibition profile of the anionic inhibitors against the α-human isoforms (hCA I and hCA II) and the two Porphyromonas gingivalis CAs (PgiCAβ and PgiCAγ) for the CO₂ hydration reaction. The figure was generated using the program Prism and excludes all the anion inhibitors showing K_I > 1 mM. The absence of the bar means that the inhibitor exhibits K_I > 1 mM. The errors were in the range of 5–10% of the shown data from three different assays.