In silico comparative structural and functional analysis of arsenite methyltransferase from bacteria, fungi, fishes, birds, and mammals

Abstract

Background Arsenic, a ubiquitous toxic metalloid, is a threat to the survival of all living organisms. Bioaccumulation of arsenic interferes with the normal physiological pathway. To overcome arsenic toxicity, organisms have developed arsenite methyltransferase enzyme, which methylates inorganic arsenite to organic arsenic MMA (III) in the presence of S-adenosylmethionine (SAM). Bacteria-derived arsM might be horizontally transported to different domains of life as arsM or as3mt (animal ortholog). A systematic study on the functional diversity of arsenite methyltransferase from various sources will be used in arsenic bioremediation. Results Several arsenite methyltransferase protein sequences of bacteria, fungi, fishes, birds, and mammals were retrieved from the UniProt database. In silico physicochemical studies confirmed the acidic, hydrophilic, and thermostable nature of these enzymes. Interkingdom relationships were revealed by performing phylogenetic analysis. Homology modeling was performed by SWISS-MODEL, and that was validated through SAVES-v.6.0. QMEAN values ranged from − 0.93 to − 1.30, ERRAT score (83–96), PROCHECK (88–92%), and other parameters suggested models are statistically significant. MOTIF and PrankWeb discovered several functional motifs and active pockets within the proteins respectively. The STRING database showed protein–protein interaction networks. Conclusion All of our in silico studies confirmed the fact that arsenite methyltransferase is a cytosolic stable enzyme with conserved sequences over a wide range of organisms. Thus, because of its stable and ubiquitous nature, arsenite methyltransferase could be employed in arsenic bioremediation.

Effects of Intestinal Microbiota on the Biological Transformation of Arsenic in Zebrafish: Contribution and Mechanism

“…Toxic iAs can be biotransformed to low/nontoxic organic forms of counterparts after metabolic reactions such as reduction, oxidation, methylation, and thiolation. ,− Arsenic methyltransferase (As3mt) is a crucial enzyme conducting the organization of iAs methylation and commonly exists in animals and microbes. For vertebrates, As3mt is mainly expressed and play roles in the liver, and their gut microbiome can produce As3mt in the intestine − By using food arsenic (predominantly with iAs III ) exposure on mice, we found that along the longitudinal axis of the digestive tract, highly toxic iAs III gradually decreased, while methyl As gradually increased. , Arsenic can also induce the prosperity of As-metabolizing bacteria, such as Seminibacterium and Metallobacterium . , By applying the fecal microbiota transplantation, intestinal microbiome, especially Faecalibacterium, were proved to protect As3mt-KO mice from acute As exposure-induced death .…”

“…For vertebrates, As3mt is mainly expressed and play roles in the liver, 25 and their gut microbiome can produce As3mt in the intestine. 26 In vitro experiments have revealed that both mouse and human feces have genes encoding As metabolism enzymes and can facilitate As biotransformation. 27−29 By using food arsenic (predominantly with iAs III ) exposure on mice, we found that along the longitudinal axis of the digestive tract, highly toxic iAs III gradually decreased, while methyl As gradually increased.…”