Comparative evaluation of structure and characteristic of peptidyl-prolyl cis-trans isomerase proteins and their function in Salmonella Typhimurium stress responses and virulence

Molecular Prediction and Correlation of the Structure and Function of Universal Stress Protein A (UspA) from Salmonella Typhimurium

Salmonella Typhimurium (ST) is a zoonotic pathogen that can cause gastroenteritis in humans when they consume contaminated food or water. When exposed to various stressors, both from living organisms (biotic) and the environment (abiotic), Salmonella Typhimurium produces Universal Stress Proteins (USPs). These proteins are gaining recognition for their crucial role in bacterial stress resistance and the ability to enter a prolonged state of growth arrest. Additionally, USPs exhibit diverse structures due to the fusion of the USP domain with different catalytic motifs, enabling them to participate in various reactions and cellular activities during stressful conditions. In this particular study, researchers cloned and analyzed the uspA gene obtained from poultry-derived strains of Salmonella Typhimurium. The gene comprises 435 base pairs, encoding a USP family protein consisting of 144 amino acids. Phylogenetic analysis demonstrated a close relationship between the uspA genes of Salmonella Typhimurium and those found in other bacterial species. We used molecular dynamics simulations and 3D structure prediction to ensure that the USPA protein was stable. Furthermore, we also carried out motif search and network analysis of protein-protein interactions. The findings from this study offer valuable insights for the development of inhibitors targeted against Salmonella Typhimurium.

Biochemical and functional characterization of Brucella abortus cyclophilins: So similar, yet so different

Brucella spp. are the etiological agent of animal and human brucellosis. We have reported previously that cyclophilins of Brucella (CypA and CypB) are upregulated within the intraphagosomal replicative niche and required for stress adaptation and host intracellular survival and virulence. Here, we characterize B. abortus cyclophilins, CypA, and CypB from a biochemical standpoint by studying their PPIase activity, chaperone activity, and oligomer formation. Even though CypA and CypB are very similar in sequence and share identical chaperone and PPIase activities, we were able to identify outstanding differential features between them. A series of differential peptide loops were predicted when comparing CypA and CypB, differences that might explain why specific antibodies (anti-CypA or anti-CypB) were able to discriminate between both cyclophilins without cross-reactivity. In addition, we identified the presence of critical amino acids in CypB, such as the Trp134 which is responsible for the cyclosporin A inhibition, and the Cys128 that leads to CypB homodimer formation by establishing a disulfide bond. Here, we demonstrated that CypB dimer formation was fully required for stress adaptation, survival within HeLa cells, and mouse infection in B. abortus. The presence of Trp134 and the Cys128 in CypB, which are not present in CypA, suggested that two different kinds of cyclophilins have evolved in Brucella, one with eukaryotic features (CypB), another (CypA) with similar features to Gram-negative cyclophilins.

Purification and characterization of Cyclophilin: a protein associated with protein folding in Salmonella Typhimurium

Salmonella Typhimurium (ST) is a Gram-negative zoonotic pathogenic bacterium that causes infectious disease in humans as well as in animals. It causes foodborne diarrheal or gastrointestinal illness and fever called salmonellosis, which is a leading cause of millions of deaths worldwide. Salmonellaenterica serovar Typhimurium (S. Typhimurium) during its pathogenesis take away the actin cytoskeleton of their host cells and this is the crucial step of its infection cycle. Cyclophilin A, a type of peptidyl-prolyl isomerase that's encoded by the ppiA gene in ST, plays pleiotropic roles in maintaining bacterial physiology. In this investigation, the proteomic characterization of the peptidyl-prolyl cis-trans isomerase- A (Cyclophilin A) from Salmonella Typhimurium is reported. Cyclophilin A (CypA) protein from Salmonella Typhimurium proved to be highly conserved and homologous protein sequence compared to other organisms. This protein was expressed in Escherichia coli followed by its purification in a recombinant form protein exhibited a characteristic PPIases activity (V_max = 0.8752 ± 0.13892 µmoles/min, K_m = 0.9315 ± 0.5670 µM) in comparison to control. The mass spectrometry analysis of Cyp A protein-peptide showed a highest sequence similarity with the cyclophilin protein of Salmonella. PPIases proteins (enzyme) data suggest that Ppi-A has roles in the protein folding that may be contributing to the virulence of Salmonella by isomerization of protein outline. These results suggest an active and vital role of this protein in protein folding along with regulation in Salmonella Typhimurium.

Identification of Salmonella Typhimurium Peptidyl-prolyl cis-trans Isomerase B (PPIase B) and Assessment of their Role in the Protein Folding

BACKGROUND

Peptidyl-prolyl cis-trans isomerase (PPIases) enzyme plays a vital role in protein folding. It catalyses the cis-trans isomerisation of peptide bonds, an essential step for newly synthesized protein to acquire its correct functional conformation in both prokaryotes and eukaryotes.

OBJECTIVE

The present study showed the biochemical and molecular characterisation of cyclophilins (PpiB), a type of peptidyl-prolyl isomerases proteins from the pathogenic bacteria Salmonella Typhimurium.

METHODS

Salmonella Typhimurium is one of the leading serovars responsible for human and animal salmonellosis globally, with the majority of human cases originating through the food chain. Here successful expression and purification of PpiB protein have been demonstrated and LC-MS based analyses showed high protein score and similarity with other PPi protein. Further the enzymatic activity of the purified recombinant PpiB was determined using Succinyl-Ala-Phe-Pro- Phe-p nitroanilide as substrate and enzyme-catalysed reaction.

RESULT

Km and Vmax were calculated and found to be Vm = 1.023 ± .06400 min/μg, Km = 0.6219 ± 0.1701 μM, respectively. We have reported for the first time the presence of Salmonella PPIase-B (PpiB) protein isoforms in salmonella genome having PPi activity.

CONCLUSION

Taken together, our data clearly showed that Salmonella Cyclophilin B (PpiB) protein is active and involved in diverse biological processes and highly similar to the different domain of Cyclophilin proteins.