Regulation and overexpression studies of YidC in Mycobacterium tuberculosis

Identifying the in vivo-induced antigenic genes is a strategy to develop DNA vaccine against Nocardia seriolae in hybrid snakehead (Channa maculata ♀ × Channa argus ♂)

Nocardia seriolae has been identified as the causative agent of fish nocardiosis, resulting in serious economic losses in aquaculture. With an aim to screen potential candidates for vaccine development against N. seriolae, the in vivo-induced genes of N. seriolae in hybrid snakehead (Channa maculate ♀ × Channa argus ♂) model were profiled via in vivo-induced antigen technology (IVIAT) in the present study, and 6 in vivo-induced genes were identified as follows: IS701 family transposase (is701), membrane protein insertase YidC (yidC), ergothioneine biosynthesis glutamate-cysteine ligase (egtA), molybdopterin respectively-dependent oxidoreductase (mol), phosphoketolase family protein (Ppl), hypothetical protein 6747 (hp6747). Additionally, the yidC was inserted into eukaryotic expression vector pcDNA3.1-myc-his-A to construct a DNA vaccine named as pcDNA-YidC to evaluate immunoprotection in hybrid snakehead after artificial challenge with N. serioale. Results showed that the transcription of yidC was detected in spleen, trunk kidney, muscle and liver in vaccinated fish, suggesting that this antigenic gene can be recombinantly expressed in fish. Meanwhile, indexes of humoral immunity were evaluated in the vaccinated fish through assessing specific-antibody IgM and serum enzyme activities, including lysozyme (LZM), superoxide dismutase (SOD), acid phosphatase (ACP) and alkaline phosphatase (AKP). Quantitative real-time PCR analysis indicated that pcDNA-YidC DNA vaccine could notably enhance the expression of immune-related genes (CD4、CD8α、MHCIIα、TNFα、IL-1β and MHCIα) in 4 tissues (spleen, trunk kidney, muscle and liver) of the vaccinated fish. Finally, an immuno-protection with a relative survival rate of 65.71 % was displayed in vaccinated fish in comparison to the control groups. Taken together, these results indicate that pcDNA-YidC DNA vaccine could boost strong immune responses in hybrid snakehead and show preferably protective efficacy against N. seriolae, indicating that IVIAT is a helpful strategy to screen the highly immunogenic antigens for vaccine development against fish nocardiosis.

Multi-Omics of Corynebacterium Pseudotuberculosis 12CS0282 and an In Silico Reverse Vaccinology Approach Reveal Novel Vaccine and Drug Targets

Corynebacterium pseudotuberculosis is an important animal pathogen, which is also able to infect humans. An optimal treatment of infections with this pathogen is not available today and consequently, more research is necessary to understand the infection process. Here, we present a combined -omics and bioinformatics approach to characterize C. pseudotuberculosis 12CS0282. The genome sequence of strain 12CS0282 was determined, analyzed in comparison with the available 130 C. pseudotuberculosis sequences and used as a basis for proteome analyses. In a reverse vaccinology approach, putative vaccine and drug targets for 12CS0208 were identified. Mass spectrometry analyses revealed the presence of multiple virulence factors even without host contact. In macrophage interaction studies, C. pseudotuberculosis 12CS0282 was highly resistant against human phagocytes and even multiplied within human THP-1 cells. Taken together, the data indicate a high pathogenic potential of the strain.

The unfoldase ClpC1 of Mycobacterium tuberculosis regulates the expression of a distinct subset of proteins having intrinsically disordered termini

The human pathogen Mycobacterium tuberculosis (Mtb) harbors a well-orchestrated Clp (caseinolytic protease) proteolytic machinery consisting of two oligomeric segments, a barrel-shaped heterotetradecameric protease core comprising the ClpP1 and ClpP2 subunits, and hexameric ring-like ATP-dependent unfoldases composed of ClpX or ClpC1. The roles of the ClpP1P2 protease subunits are well-established in Mtb, but the potential roles of the associated unfoldases, such as ClpC1, remain elusive. Using a CRISPR interference-mediated gene silencing approach, here we demonstrate that clpC1 is indispensable for the extracellular growth of Mtb and for its survival in macrophages. The results from isobaric tags for relative and absolute quantitation-based quantitative proteomic experiments with clpC1- and clpP2-depleted Mtb cells suggested that the ClpC1P1P2 complex critically maintains the homeostasis of various growth-essential proteins in Mtb, several of which contain intrinsically disordered regions at their termini. We show that the Clp machinery regulates dosage-sensitive proteins such as the small heat shock protein Hsp20, which exists in a dodecameric conformation. Further, we observed that Hsp20 is poorly expressed in WT Mtb and that its expression is greatly induced upon depletion of clpC1 or clpP2 Remarkably, high Hsp20 protein levels were detected in the clpC1(-) or clpP2(-) knockdown strains but not in the parental bacteria, despite significant induction of hsp20 transcripts. In summary, the cellular levels of oligomeric proteins such as Hsp20 are maintained post-translationally through their recognition, disassembly, and degradation by ClpC1, which requires disordered ends in its protein substrates.