Recombinant Rhodopirellula baltica Proline--tRNA ligase (proS), partial

Biochemical Characteristics and Sequence Overview

The recombinant proS protein (Uniprot ID: Q7UGJ7) is a class I aminoacyl-tRNA synthetase (aaRS) with a predicted length of 506 amino acids. The partial recombinant form retains key catalytic domains necessary for proline activation and tRNA charging.

Key Features

Functional Role in Translation

ProRS catalyzes a two-step reaction:

1. Activation Step: Proline + ATP → Proline-AMP + PPi

2. Charging Step: Proline-AMP + tRNA^Pro → Prolyl-tRNA^Pro + AMP

Editing Mechanisms
ProRS employs pre- and post-transfer editing to prevent misacylation:

• Pre-transfer: Hydrolysis of non-cognate amino acid (e.g., alanine) adenylates.

• Post-transfer: Deacylation of mischarged tRNA^Pro.
  These mechanisms are conserved across bacterial ProRS homologs, including Rhodopirellula baltica .

Recombinant Production and Purification

The partial proS protein is expressed in E. coli and purified to near-homogeneity. Key details include:

Expression and Purification

Interaction Network and Predicted Partners

ProS interacts with other aaRS enzymes, forming a functional network in translation machinery. Predicted partners include:

Interaction Partners

These interactions highlight proS’s role in coordinating amino acid charging and quality control .

Research Applications and Potential

While specific kinetic parameters (e.g., $K_m$, $k_{cat}$) for R. baltica proS remain uncharacterized, its recombinant form serves as a tool for:

• Basic Research: Studying tRNA charging mechanisms and editing pathways.

• Biotechnology: Screening inhibitors targeting ProRS in pathogens (e.g., Pseudomonas aeruginosa) .

• Genomic Context: R. baltica’s genome harbors unique biosynthetic pathways (e.g., compatible solutes), suggesting potential for metabolic engineering .

Limitations and Future Directions

• Structural Gaps: The partial nature of the recombinant protein may limit functional studies.

• Kinetic Data: No published $K_m$ or $k_{cat}$ values exist for R. baltica proS; comparisons rely on homologs like P. aeruginosa ProRS ($K_m = 5.5 \, \mu M$, $k_{cat} = 0.2 \, s^{-1}$) .

• Therapeutic Targets: ProRS editing domains (e.g., Lys279 in P. aeruginosa) represent potential targets for antimicrobial drug design .