In silico insight into structural and functional attributes of arsenic resistance proteins from Rhizobium radiobacter strain F4

Abstract

Arsenic (As) in environmental matrices is often associated with toxic hazardous nature to the environment and public health. To overcome its induced toxicity and mitigation, numerous methods have existed. Despite the available methods, most of them are complex cost-bearing, and require long-term assays. Endophytic bacteria are competent to reduce the As concentration in an eco-friendly manner. The endofungal bacterium Rhizobium radiobacter strain F4 (RrF4) is associated with the fungal mutualist Serendipita (syn. Piriformospora indica). This bacterium can colonize a wide variety of plants and has been observed to promote their growth and development. In addition to its growth-promoting properties, S. indica confers protection against As toxicity upon its host. However, the extent to which its symbiotic partner RrF4 contributes to this resistance remains unclear. In this context associated proteins become a focus point of study to bridge the existing research gap. In the presented study in-silico exploration was carried out to unravel As resistance in RrF4. A total of seven proteins; Arsenical resistance operon repressor, Arsenical pump membrane protein, Arsenical resistance operon repressor, Arsenical resistance operon repressor, arsR-type domain-containing protein, ArsR family transcriptional regulator, and arsenate reductase have been characterized for structural and functional attributes deploying different in-silico toolsets (SWISS-MODEL, CABS-flex 2.0, ProtParam, and SOPMA, etc.). Findings suggested considerable variability in structure, and physicochemical parameters. The far highest helix component observed for Arsenical resistance operon repressor (66.95%) and the lowest for arsR-type domain-containing protein (21.04%) was observed. Arsenical resistance operon repressor seemed to be simplest in its three-dimensional structure, whilst the Arsenical pump membrane was predicted with complexity in its structural aspect. Protein-protein interactions prediction also revealed the diverse interactions among others. Notwithstanding, further exploration with As binding and transformation remain unexplored for future research. Findings herein could be utilized as a blueprint for a protein engineering approach for improved As detoxification in an eco-friendly manner.