Characterization of substrate specificity and novel autoprocessing mechanism of dipeptidase A from Prevotella intermedia

Microbiota-assisted therapy for systemic inflammatory arthritis: advances and mechanistic insights

Research on the influence of gut microbiota on systemic inflammatory arthritis has exploded in the past decade. Gut microbiota changes may be a crucial regulatory component in systemic inflammatory arthritis. As a result of advancements in the field, microbiota-assisted therapy has evolved, but this discipline is still in its infancy. Consequently, we review the limitations of current systemic inflammatory arthritis treatment, analyze the connection between the microbiota and arthritis, and summarize the research progress of microbiota regulating systemic inflammatory arthritis and the further development aspects of microbiota-assisted therapy. Finally, the partial mechanisms of microbiota-assisted therapy of systemic inflammatory arthritis are being discussed. In general, this review summarizes the current progress, challenges, and prospects of microbiota-assisted therapy for systemic inflammatory arthritis and points out the direction for the development of microbiota-assisted therapy in the future.

Prevotella: An insight into its characteristics and associated virulence factors

Prevotella species, a gram-negative obligate anaerobe, is commonly associated with human infections such as dental caries and periodontitis, as well as other conditions such as chronic osteomyelitis, bite-related infections, rheumatoid arthritis and intestinal diseases like ulcerative colitis. This generally harmless commensal possesses virulence factors such as adhesins, hemolysins, secretion systems exopolysaccharide, LPS, proteases, quorum sensing molecules and antibiotic resistance to evolve into a well-adapted pathogen capable of causing successful infection and proliferation in the host tissue. This review describes several of these virulence factors and their advantage to Prevotella spp. in causing inflammatory diseases like periodontitis. In addition, using genome analysis of Prevotella reference strains, we examined other putative virulence determinants which can provide insights as biomarkers and be the targets for effective interventions in Prevotella related diseases like periodontitis.

Expanded substrate specificity supported by P1' and P2' residues enables bacterial dipeptidyl-peptidase 7 to degrade bioactive peptides

Dipeptide production from extracellular proteins is crucial for Porphyromonas gingivalis, a pathogen related to chronic periodontitis, because its energy production is entirely dependent on the metabolism of amino acids predominantly incorporated as dipeptides. These dipeptides are produced by periplasmic dipeptidyl-peptidase (DPP)4, DPP5, DPP7, and DPP11. Although the substrate specificities of these four DPPs cover most amino acids at the penultimate position from the N terminus (P1), no DPP is known to cleave penultimate Gly, Ser, Thr, or His. Here, we report an expanded substrate preference of bacterial DPP7 that covers those residues. MALDI-TOF mass spectrometry analysis demonstrated that DPP7 efficiently degraded incretins and other gastrointestinal peptides, which were successively cleaved at every second residue, including Ala, Gly, Ser, and Gln, as well as authentic hydrophobic residues. Intravenous injection of DPP7 into mice orally administered glucose caused declines in plasma glucagon-like peptide-1 and insulin, accompanied by increased blood glucose levels. A newly developed coupled enzyme reaction system that uses synthetic fluorogenic peptides revealed that the P1′ and P2′ residues of substrates significantly elevated k_cat values, providing an expanded substrate preference. This activity enhancement was most effective toward the substrates with nonfavorable but nonrepulsive P1 residues in DPP7. Enhancement of k_cat by prime-side residues was also observed in DPP11 but not DPP4 and DPP5. Based on this expanded substrate specificity, we demonstrate that a combination of DPPs enables proteolytic liberation of all types of N-terminal dipeptides and ensures P. gingivalis growth and pathogenicity.

Dipeptidyl-peptidases: Key enzymes producing entry forms of extracellular proteins in asaccharolytic periodontopathic bacterium Porphyromonas gingivalis

Porphyromonas gingivalis, a pathogen of chronic periodontitis, is an asaccharolytic microorganism that solely utilizes nutritional amino acids as its energy source and cellular constituents. The bacterium is considered to incorporate proteinaceous nutrients mainly as dipeptides, thus exopeptidases that produce dipeptides from polypeptides are critical for survival and proliferation. We present here an overview of dipeptide production by P. gingivalis mediated by dipeptidyl-peptidases (DPPs), e.g., DPP4, DPP5, DPP7, and DPP11, serine exopeptidases localized in periplasm, which release dipeptides from the N-terminus of polypeptides. Additionally, two other exopeptidases, acylpeptidyl-oligopeptidase (AOP) and prolyl tripeptidyl-peptidase A (PTP-A), which liberate N-terminal acylated di-/tri-peptides and tripeptides with Pro at the third position, respectively, provide polypeptides in an acceptable form for DPPs. Hence, a large fraction of dipeptides is produced from nutritional polypeptides by DPPs with differential specificities in combination with AOP and PTP-A. The resultant dipeptides are then incorporated across the inner membrane mainly via a proton-dependent oligopeptide transporter (POT), a member of the major facilitator superfamily. Recent studies also indicate that DPP4 and DPP7 directly link between periodontal and systemic diseases, such as type 2 diabetes mellitus and coagulation abnormality, respectively. Therefore, these dipeptide-producing and incorporation molecules are considered to be potent targets for prevention and treatment of periodontal and related systemic diseases.