The emergence of antibiotic resistant bacteria is one of the biggest threats to human health worldwide. In 2017, World Health Organization listed the world’s most dangerous antibiotic-resistant bacteria or “superbugs,” such as carbapenem-resistant Pseudomonas aeruginosa and Escherichia coli, indicating the highest priority needs for new antibiotics. The possibility that such infectious diseases may soon be untreatable, due to decreased antibiotic efficacy, creates an urgent need for novel and alternative antimicrobials. Antimicrobial peptides are naturally occurring small molecules found in the innate immunity of mammals, plants and bacteria, and are potentially therapeutic candidates against drug-resistant bacteria. In this study, we examine the antimicrobial activities of the cytotoxic peptides derived from the basic region (BR) of the human hexamethylene bisacetamide-inducible protein 1 (HEXIM1). We found that, when fused with a cell penetrating peptide, the HEXIM1 BR peptide and its derivative, BR-RRR12, exhibited inhibitory activities against selected “superbugs.” Negligible effects on the viability of human keratinocyte cell line were observed when the bactericidal dosages of HEXIM1 BR peptides were used. Different killing kinetics were observed between the membrane permeabilizing antimicrobial peptides and HEXIM1 BR peptides, suggesting that a different antimicrobial mechanism might be utilized by the HEXIM1 BR peptides. Using an in vitro translation system based on E. coli lysates, we found that HEXIM1 BR peptides blocked bacterial translation. Taken together, we identify the HEXIM1 BR peptide as a novel antimicrobial peptide with potent inhibitory activity against antibiotic-resistant “superbugs.”

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen that is found ubiquitously in the environment. It is also the cause of nosocomial infections, which affects patients with cystic fibrosis (CF) and cathether-related infections. Treatment and eradication of P. aeruginosa is an uphill task as it has already developed resistance to many commonly used antibiotics. Some of the resistance mechanisms that P. aeruginosa employ are having low cell wall permeability, developing efflux system to pump antibiotics out, producing enzymes to inactivate antibiotics, modifying antibiotic targets, forming biofilm as a protection layer against antibiotics, and turning into more pathogenic small colony variant form. In addition, P. aeruginosa uses a host of signaling mechanisms, such as secretion system and quorum sensing, to aid its virulence. With numerous resistance mechanisms developed against conventional antibiotics, new strategies to treat P. aeruginosa infection are required. Bacteriophages such as natural bacteria viruses and studies have suggested that they can be used as an alternative to antibiotics for treatment against P. aeruginosa infections. However, phage therapy also shares the same problem with that of antibiotics, i.e., the development and emergence of bacteria resistance by masking or altering surface recognition features, inhibiting phage DNA injection and employing abortive infection (Abi) system. Another alternative treatment strategy is to use antimicrobial peptides, which are small cationic peptides that are naturally found in most organisms’ immune system. These peptides disrupt cell membrane and key cellular processes, which requires major gene alteration if evasion is needed. Hence, lowering likelihood of resistance development. This paper aims to review our current understanding of the clinical implications of P. aeruginosa infections, the mechanisms of antibiotic resistance, phage-inspired and antimicrobial peptide approaches for treatment of P. aeruginosa infections.

Reducing sugar intake lowers the risk of obesity and associated metabolic disorders. Currently, this is achieved using artificial non-nutritive sweeteners, where their safety is widely debated and their contributions in various diseases is controversial. Emerging research suggests that these sweeteners may even increase the risk of cancer and cardiovascular problems, and some people experience gastrointestinal issues as a result of using them. A safer alternative to artificial sweeteners could be sweet-tasting proteins, such as brazzein, which do not appear to have any adverse health effects. In this study, protein language models were explored as a new method for protein design of brazzein. This innovative approach resulted in the identification of unexpected mutations, which opened up new possibilities for engineering thermostable and potentially sweeter versions of brazzein. To facilitate the characterization of the brazzein mutants, a simplified procedure was developed for expressing and analyzing related proteins. This process involved an efficient purification method using Lactococcus lactis (L. lactis), a generally recognized as safe (GRAS) bacterium, as well as taste receptor assays to evaluate sweetness. The study successfully demonstrated the potential of computational design in producing a more heat-resistant and potentially more palatable brazzein variant, V23.