Structure-Function and Industrial Relevance of Bacterial Aminopeptidase P

The role of DsbA and PepP genes in the environmental tolerance and virulence factors of Cronobacter sakazakii

Cronobacter sakazakii, an opportunity foodborne pathogen, could contaminate a broad range of food materials and cause life-threatening symptoms in infants. The bacterial envelope structure contribute to bacterial environment tolerance, biofilm formation and virulence in various in Gram-negative bacteria. DsbA and PepP are two important genes related to the biogenesis and stability of bacterial envelope. In this study, the DsbA and PepP were deleted in C. sakazakii to evaluate their contribution to stress tolerance and virulence of the pathogen. The bacterial environment resistance assays showed DsbA and PepP are essential in controlling C. sakazakii resistance to heat and desiccation in different mediums, as well as acid, osmotic, oxidation and bile salt stresses. DsbA and PepP also played an important role in regulating biofilm formation and motility. Furthermore, DsbA and PepP deletion weaken C. sakazakii adhesion and invasion in Caco-2, intracellular survival and replication in RAW 264.7. qRT-PCR results showed that DsbA and PepP of C. sakazakii played roles in regulating the expression of several genes associated with environment stress tolerance, biofilm formation, bacterial motility and cellular invasion. These findings indicate that DsbA and PepP played an important regulatory role in the environment resisitance, biofilm formation and virulence of C. sakazakii, which enrich understanding of genetic determinants of adaptability and virulence of the pathogen.

Exploring the Antarctic aminopeptidase P from Pseudomonas sp. strain AMS3 through structural analysis and molecular dynamics simulation

Aminopeptidase P (APPro) is a crucial metalloaminopeptidase involved in amino acid cleavage from peptide N-termini, playing essential roles as versatile biocatalysts with applications ranging from pharmaceuticals to industrial processes. Despite acknowledging its potential for catalysis in lower temperatures, detailed molecular basis and biotechnological implications in cold environments are yet to be explored. Therefore, this research aims to investigate the molecular mechanisms underlying the cold-adapted characteristics of APPro from Pseudomonas sp. strain AMS3 (AMS3-APPro) through a detailed analysis of its structure and dynamics. In this study, structure analysis and molecular dynamics (MD) simulation of a predicted model of AMS3-APPro has been performed at different temperatures to assess structural flexibility and thermostability across a temperature range of 0-60 °C over 100 ns. The MD simulation results revealed that the structure were able to remain stable at low temperatures. Increased temperatures present a potential threat to the overall stability of AMS3-APPro by disrupting the intricate hydrogen bond networks crucial for maintaining structural integrity, thereby increasing the likelihood of protein unfolding. While the metal binding site at the catalytic core exhibits resilience at higher temperatures, highlighting its local structural integrity, the overall enzyme structure undergoes fluctuations and potential denaturation. This extensive structural instability surpasses the localized stability observed at the metal binding site. Consequently, these assessments offer in-depth understanding of the cold-adapted characteristics of AMS3-APPro, highlighting its capability to uphold its native conformation and stability in low-temperature environments. In summary, this research provides valuable insights into the cold-adapted features of AMS3-APPro, suggesting its efficient operation in low thermal conditions, particularly relevant for potential biotechnological applications in cold environments.Communicated by Ramaswamy H. Sarma.

Understanding the structure and function of Plasmodium aminopeptidases to facilitate drug discovery

Malaria continues to be the most widespread parasitic disease affecting humans globally. As parasites develop drug resistance at an alarming pace, it has become crucial to identify novel drug targets. Over the last decade, the metalloaminopeptidases have gained importance as potential targets for new antimalarials. These enzymes are responsible for removing the N-terminal amino acids from proteins and peptides, and their restricted specificities suggest that many perform unique and essential roles within the malaria parasite. This mini-review focuses on the recent progress in structure and functional data relating to the Plasmodium metalloaminopeptidases that have been validated or shown promise as new antimalarial drug targets.

Evolution and Role of Proteases in Campylobacter jejuni Lifestyle and Pathogenesis

Infection with the main human food-borne pathogen Campylobacter jejuni causes campylobacteriosis that accounts for a substantial percentage of gastrointestinal infections. The disease usually manifests as diarrhea that lasts for up to two weeks. C. jejuni possesses an array of peptidases and proteases that are critical for its lifestyle and pathogenesis. These include serine proteases Cj1365c, Cj0511 and HtrA; AAA+ group proteases ClpP, Lon and FtsH; and zinc-dependent protease PqqE, proline aminopeptidase PepP, oligopeptidase PepF and peptidase C26. Here, we review the numerous critical roles of these peptide bond-dissolving enzymes in cellular processes of C. jejuni that include protein quality control; protein transport across the inner and outer membranes into the periplasm, cell surface or extracellular space; acquisition of amino acids and biofilm formation and dispersal. In addition, we highlight their role as virulence factors that inflict intestinal tissue damage by promoting cell invasion and mediating cleavage of crucial host cell factors such as epithelial cell junction proteins. Furthermore, we reconstruct the evolution of these proteases in 34 species of the Campylobacter genus. Finally, we discuss to what extent C. jejuni proteases have initiated the search for inhibitor compounds as prospective novel anti-bacterial therapies.

Biochemical Characterisation and Structure Determination of a Novel Cold-Active Proline Iminopeptidase from the Psychrophilic Yeast, Glaciozyma antarctica PI12

Microbial proteases constitute one of the most important groups of industrially relevant enzymes. Proline iminopeptidases (PIPs) that specifically release amino-terminal proline from peptides are of major interest for applications in food biotechnology. Proline iminopeptidase has been extensively characterised in bacteria and filamentous fungi. However, no similar reports exist for yeasts. In this study, a protease gene from Glaciozyma antarctica designated as GaPIP was cloned and overexpressed in Escherichia coli. Sequence analyses of the gene revealed a 960 bp open reading frame encoding a 319 amino acid protein (35,406 Da). The purified recombinant GaPIP showed a specific activity of 3561 Umg−1 towards L-proline-p-nitroanilide, confirming its identity as a proline iminopeptidase. GaPIP is a cold-active enzyme with an optimum activity of 30 °C at pH 7.0. The enzyme is stable between pH 7.0 and 8.0 and able to retain its activity at 10–30 °C. Although GaPIP is a serine protease, only 25% inhibition by the serine protease inhibitor, phenylmethanesulfonylfluoride (PMSF) was recorded. This enzyme is strongly inhibited by the presence of EDTA, suggesting that it is a metalloenzyme. The dimeric structure of GaPIP was determined at a resolution of 2.4 Å. To date, GaPIP is the first characterised PIP from yeasts and the structure of GaPIP is the first structure for PIP from eukaryotes.