Phylogenetic analysis and characterization of arsenic (As) transforming bacterial marker proteins following isolation of As-tolerant indigenous bacteria

Abstract

Marker proteins play a significant role in bacterial arsenic (As) transformation. Phylogenetic analysis and three-dimensional (3D) characteristics of As transforming bacterial marker proteins guide the evolutionary origin and As transforming potential of the species. Indeed, As-tolerant bacteria also show a significant level of As transformation. Hence, characterization of As transforming bacterial marker proteins, isolation of As transforming bacteria, and proper integration of the findings may guide to elucidate how bacteria transform As. Therefore, phylogenetic analysis and 3D characterization of As transforming bacterial marker protein following isolation of potential indigenous As-tolerant indigenous bacteria were done to explore the mechanism of bacterial As transformation. Phylogenetic analysis of ten As transforming marker proteins (arsA, arsB, arsC, arsD, arsR, aioA, arrA, aioB, acr1, and acr3) in 20 potential bacterial genomes (except 19 for the acr3) were studied. Some bacterial genomes featured up to five marker proteins, and therefore, 3D characteristics of the marker proteins were analyzed in those genomes having three-to-five marker proteins. In phylogeny, species in close clades represent their phylogenetic resemblances and may have similar functions. P. aeruginosa, E. coli, and K. pneumonia were found to be more effective due to having the highest number (five) of marker proteins. In 3D protein modeling, most of the marker proteins were found to be active. Among 19 indigenous bacterial isolates, multiple isolates showed tolerance up to 50 mM As(III) and 250 mM As(V), which may potentially transform a significant quantities of As. Hence, integration of the results of phylogenetic analysis, 3D protein characteristics, and As tolerance in the bacterial isolates could guide to explore the mechanism of how bacteria transform As at cellular and molecular levels.

Keywords: 3D protein structure; Arsenic remediation; Arsenic transforming marker proteins; Arsenic-tolerant bacteria.