Characterization of Aminopeptidase P from the Unicellular Cyanobacterium Synechocystis sp. PCC6803

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.

Characterization of a novel aminopeptidase P from Trichinella spiralis and its participation in the intrusion of intestinal epithelial cells

Aminopeptidases P are metalloproteases belonging to the M24 peptidase family. It specifically hydrolyzes the N-terminus of polypeptides free of acidic amino acids, and plays an important role in the nutrition, metabolism and growth of parasites. The aim of this study was to characterize a novel Trichinella spiralis aminopeptidase P (TsAPP) and to investigate its functions in the invasion of T. spiralis. TsAPP contained two domains of creatinase (a creatinase N and creatinase N2) and a domain of peptidase M24C and APP. The complete TsAPP sequence was cloned and expressed in Escherichia coli BL21 cells. The recombinantly produced TsAPP was used to raise polyclonal antibodies that were subsequently used to detect the expression of the protein in the different life stages of T. spiralis. TsAPP was expressed in various T. spiralis stages. TsAPP was primarily localized in the cuticle, stichosome and intrauterine embryos of this nematode. rTsAPP has an enzymatic activity of a natural aminopeptidase P to hydrolyze the substrate H-Ala-Pro-OH. rTsAPP promoted the larval intrusion of intestinal epithelium cells (IECs). The results showed that TsAPP is involved in the T. spiralis intrusion of IECs and it might be a potential candidate vaccine target against Trichinella infection.