Recombinant Staphylococcus aureus tRNA pseudouridine synthase A (truA)

Introduction to Recombinant Staphylococcus aureus tRNA Pseudouridine Synthase A (TruA)

Recombinant Staphylococcus aureus tRNA pseudouridine synthase A (TruA) is an engineered enzyme responsible for catalyzing pseudouridylation, a conserved post-transcriptional RNA modification. TruA belongs to the TruA family of pseudouridine synthases (PUS), which isomerize uridine to pseudouridine (Ψ) in tRNA and other RNAs. This modification enhances RNA stability, influences translational fidelity, and modulates RNA-protein interactions critical for bacterial survival and adaptation .

Enzymatic Mechanism

TruA catalyzes Ψ formation via a base-flipping mechanism, displacing the target uridine into its active site for isomerization. This process does not require cofactors but relies on structural features of the RNA substrate, such as:

• Base-paired regions adjacent to the target uridine.

• Stem-loop configurations resembling tRNA anticodon or TΨC domains .

Functional Significance

TruA-mediated pseudouridylation in S. aureus likely contributes to:

1. tRNA Stability: Modifying positions in tRNA anticodon stems to optimize ribosomal interactions.

2. Virulence Regulation: Indirect effects on pathogenicity via RNA structural remodeling, though direct links require further study .

Genetic Context

• truA is part of the core genome, but its activity may intersect with mobile genetic elements (e.g., SCCmes, ICEs) that drive recombination hotspots in S. aureus .

• Homologs like Pus1 in yeast show mRNA-modifying activity, suggesting TruA could have broader substrate versatility in bacteria .

Key Research Findings

• Vs. Eukaryotic PUS1: TruA lacks the N-terminal extension of PUS1, limiting its ability to bind larger RNA substrates like spliceosomal RNAs .

• Vs. Pus4/Pus7: TruA does not require tRNA-like structures for activity, unlike Pus4/Pus7, which modify mRNA via tRNA-mimicry .

Biotechnological Uses

• RNA Engineering: Recombinant TruA is used to introduce Ψ modifications in synthetic RNAs for stability studies or therapeutic design .

• Antimicrobial Targeting: TruA’s essential role in tRNA maturation makes it a potential target for novel antibiotics, though no inhibitors are currently reported .

Challenges

• Substrate Specificity: TruA’s promiscuity complicates mechanistic studies, necessitating structural models (e.g., co-crystallization with S. aureus tRNA) .