IdeS, a secreted proteinase of Streptococcus pyogenes, is bound to a nuclease at the bacterial surface where it inactivates opsonizing IgG antibodies

Structural insights into the role of the prosegment binding loop in a papain-superfamily cysteine protease from Treponema denticola

Periodontal diseases afflict 20-50% of the global population and carry serious health and economic burdens. Chronic periodontitis is characterized by inflammation of the periodontal pocket caused by dysbiosis. This dysbiosis is coupled with an increase in the population of Treponema denticola, a spirochete bacterium with high mobility and invasivity mediated by a number of virulence factors. One such virulence factor is TDE0362, a multidomain protein with a carboxy-terminal papain-superfamily cysteine protease (C0362). Most papain-superfamily cysteine proteases are produced as proenzymes with a prodomain that interacts with the prosegment binding loop (PBL), requiring proteolytic processing for full activation. Previous studies have indicated that C0362 is not produced as a proenzyme, suggesting an alternative regulatory mechanism. We previously determined the crystal structure of C0362 captured in an inactive conformation with an oxidized catalytic cysteine and a disordered PBL. In this follow-up study, we evaluated the active-site architecture and the PBL in two mutant (Y559A and C412S) structures and an inhibitor-bound (E64) structure to provide insight into the role that the PBL plays in the generation of active enzyme. Our results implicate Tyr559 as playing a critical role in the transition of the enzyme to an active state. We subsequently utilized the structural information to generate models of C0362 bound to human complement factors C3 and C4. Collectively, our results provide insight into the regulatory mechanism and putative substrate-binding interfaces of C0362, highlighting avenues of further research towards inhibition of this essential virulence factor.

A breath of fresh air: inhaled antibodies to combat respiratory infectious diseases - a clinical trial overview

INTRODUCTION

With the worldwide growing burden of respiratory tract infections (RTIs), innovative therapeutic approaches are in high demand. Inhaled antibodies (Abs) represent a promising avenue, offering targeted treatment options with potentially better therapeutic index compared to traditional delivery methods.

AREAS COVERED

This comprehensive review summarizes the challenges faced in delivering Abs by (intranasal and pulmonary) inhalation. It outlines the physiological and biological barriers encountered by inhaled drugs, as well as the influence of delivery devices and formulation on the deposition and efficacy of inhaled molecules. Moreover, it provides a detailed overview of the current clinical trial landscape of inhaled anti-RTI Abs, highlighting the progress in the development of inhaled Abs targeting a range of pathogens, such as severe acute respiratory syndrome coronavirus 2 and respiratory syncytial virus. The mechanism of action, therapeutic targets, and clinical outcomes of these novel therapies are detailed.

EXPERT OPINION

Delivery of Abs by inhalation faces several challenges. Addressing these challenges and developing specific approaches to deliver inhaled Abs represent a promising avenue for the development of the next generation of inhaled Abs. By offering targeted, localized therapy with the potential for a better therapeutic index, inhaled Abs could significantly improve outcomes for patients with RTIs.

Application of microbial enzymes in medicine and industry: current status and future perspectives

Microbes are a major source of enzymes due to their ability to be mass-cultivated and genetically modified. Compared with plant and animal enzymes, microbial enzymes are more stable and active. Enzymes are generally classified into six classes based on their reaction, substrate specificity and mechanism of action. In addition to their application in medicine for treating diseases, these compounds are used as anti-inflammatory, thrombolytic and digestive agents. However, challenges such as immunogenicity, tissue specificity and short in vivo half-life make clinical trials complex. Enzymes are metabolic catalysts in industry and their production and extraction must be optimized to preserve profitability due to rising demand. The present review highlights the increasing importance of bacterial enzymes in industry and medicine and explores methods for their production, extraction and purification.

Immunomodulating Enzymes from Streptococcus pyogenes-In Pathogenesis, as Biotechnological Tools, and as Biological Drugs

Streptococcus pyogenes, or Group A Streptococcus, is an exclusively human pathogen that causes a wide variety of diseases ranging from mild throat and skin infections to severe invasive disease. The pathogenesis of S. pyogenes infection has been extensively studied, but the pathophysiology, especially of the more severe infections, is still somewhat elusive. One key feature of S. pyogenes is the expression of secreted, surface-associated, and intracellular enzymes that directly or indirectly affect both the innate and adaptive host immune systems. Undoubtedly, S. pyogenes is one of the major bacterial sources for immunomodulating enzymes. Major targets for these enzymes are immunoglobulins that are destroyed or modified through proteolysis or glycan hydrolysis. Furthermore, several enzymes degrade components of the complement system and a group of DNAses degrade host DNA in neutrophil extracellular traps. Additional types of enzymes interfere with cellular inflammatory and innate immunity responses. In this review, we attempt to give a broad overview of the functions of these enzymes and their roles in pathogenesis. For those enzymes where experimentally determined structures exist, the structural aspects of the enzymatic activity are further discussed. Lastly, we also discuss the emerging use of some of the enzymes as biotechnological tools as well as biological drugs and vaccines.