RpPbpT

RpPbpT is a gene-protein designation used in bacterial genome annotations to refer to a penicillin-binding protein–like transpeptidase in some Rhodopseudomonas species, including Rhodopseudomonas palustris. The RpPbpT gene is generally annotated as encoding a periplasmic enzyme associated with the cell wall–synthesis apparatus, and it is classified within the broader family of penicillin-binding proteins (PBPs).

The predicted protein is localized to the periplasm and is thought to participate in peptidoglycan remodeling during cell wall synthesis. As a PBP-like enzyme, RpPbpT is presumed to possess transpeptidase activity that contributes to cross-linking of peptidoglycan strands, a process essential for maintaining cell shape and envelope integrity. The exact catalytic features and substrate preferences of RpPbpT remain to be experimentally validated in Rhodopseudomonas species.

Genomic context and evolution: RpPbpT has been identified in multiple strains within the Rhodopseudomonas lineage, where it often coexists with other cell envelope–related genes. Comparative analyses show varying degrees of sequence conservation with PBPs from related bacteria, supporting its designation as a PBP-like protein rather than a canonical cytosolic enzyme.

Current status and use: Direct biochemical characterization of RpPbpT is limited, and functional assignments are primarily based on sequence homology and domain predictions. RpPbpT serves as a target for comparative genomics studies aiming to elucidate the diversity of peptidoglycan remodeling enzymes in photosynthetic, Gram-negative bacteria. Further experimental work is needed to confirm its activity, regulation, and role in antibiotic response.