Biology subjects

Robinson, V. L.

Publications and source records attributed to Robinson, V. L..

2 recordsLinked to original sources

bioRxiv2025

An apicoplast localized GTPase is essential for Toxoplasma gondii survival

The apicoplast is an essential organelle found in Apicomplexa, a large phylum of intracellular eukaryotic pathogens. The apicoplast produces metabolites that are utilized for membrane biogenesis and energy production. A majority of apicoplast resident proteins are encoded by the nuclear genome and are trafficked to the apicoplast, and are referred to as Nuclear Encoded and Apicoplast Targeted (NEAT) proteins. In this study, we characterized a NEAT protein named TgBipA, that is a homolog of the highly conserved prokaryotic translational GTPase BipA. BipA is essential for bacterial survival in stress conditions and functions through interactions with the prokaryotic ribosome, although its role is not fully understood. Through genetic knockouts of TgBipA and immunofluorescence imaging we show that loss of TgBipA results in apicoplast genome replication defects, disruption of NEAT trafficking, loss of the apicoplast, and subsequently parasite death. Furthermore, we show through comparative studies that this phenotype closely resembles the delayed death phenomenon observed when inhibiting apicoplast translation. Finally, we show that TgBipA is an active GTPase in vitro, and its GTP hydrolysis activity is critical for its cellular function. Our findings demonstrate TgBipA is a GTPase which has an essential role in apicoplast maintenance, providing new insight into the cellular processes of the organelle. Importance StatementToxoplasma gondii, and many other parasites in the phylum Apicomplexa, are pathogens with significant medical and veterinary importance. Most Apicomplexa contain a non-photosynthetic plastid organelle named the apicoplast. This organelle produces essential metabolites and perturbation of apicoplast function results in parasite death. The apicoplast contains bacterial-like pathways for apicoplast genome replication and expression. Thus, the discovery of the apicoplast lead to optimism that this organelle would provide a wealth of anti-parasitic drug targets. Therefore, the identification and characterization of new apicoplast proteins could provide new opportunities for therapeutic development. In this study we characterized the function of a protein called TgBipA, a homolog of a highly conserved bacterial GTPase bipA which has been implicated in maturation of the 50S ribosomal subunit and adaptation to cellular stress. We show that TgBipA is essential for apicoplast maintenance and parasite survival.

microbiology↗

bioRxiv2025

Identification and characterization of the surface layer protein AvsA in outer membrane vesicles, antibiotic resistance, and in vivo host colonization in Aeromonas veronii

Outer membrane vesicles (OMVs) are important in bacterial communication and the transfer of virulence factors. In this study, we identified and characterized the surface layer protein (SLP) AvsA (Aeromonas veronii surface protein A) in the OMVs of Aeromonas veronii Hm21, a strain isolated from the medicinal leech Hirudo verbana. The surface layer proteins (SLPs) play critical roles in how bacteria interact with each other and their environments, particularly in mediating antibiotic resistance and facilitating host colonization. Furthermore, we investigate the ability of AvsA to confer protection against antibiotics, affect biofilm formation, and contribute to host colonization, providing insight into antibiotic resistance and two crucial factors contributing to the persistence of the bacteria in its host. Our findings suggest that AvsA enhances antibiotic tolerance, facilitates biofilm development, and is important for successful colonization of the leech digestive tract. These data demonstrate that AvsA performs important roles in a wide range of critical phenotypes. This work provides insights into the functional significance of SLPs in A. veronii and highlights AvsA as a potential target for modulating bacterial colonization and resilience against antibiotics. ImportanceOuter membrane vesicles (OMVs) are important for bacterial communication, pathogenesis, and stress adaptation, yet how this is accomplished remains poorly understood. Here, we identify and characterize a surface layer protein (SLP), AvsA, associated with OMVs in Aeromonas veronii Hm21. Bioinformatic, phylogenetic, and mass spectrometry analyses suggest that Aeromonas veronii ORF M001_06550 encodes a surface layer protein (SLP) with high similarity to a characterized A. hydrophila SLP, supporting its designation as Aeromonas veronii Surface Protein A (AvsA). AvsA forms a paracrystalline layer on bacterial cells and OMVs. Functionally, AvsA contributes to antibiotic resistance, enhances biofilm formation, and is essential for colonization in a symbiotic host, the medicinal leech. These findings highlight a novel role of SLPs in bacterial physiology and host interactions. Given the widespread presence of AvsA homologs, our study provides insights into conserved bacterial mechanisms that may be relevant for both pathogenic and beneficial host-microbe interactions.

microbiology↗