Alleviation of Metalloid‐Containing Methionine Analog‐Induced Toxicity Using Chemically Defined Media Supplementation

Abstract

X‐ray crystallography continues to be the most widely used method for protein structure determination. Most naturally occurring atoms lack the mass to sufficiently diffract electrons and thus, multiple isomorphous replacement (MIR) via the incorporation of metalloid‐containing analogs, such as selenomethionine, remains a valid solution to solve the phase problem associated with x‐ray crystallography. However, selenomethionine adversely affects cells in vivo and is considered cytotoxic. Through a proteomic study performed in 2013, differentially expressed proteins were identified from both telluromethionyl and selenomethionyl‐incorporated E. coli DL41 (DE3) (pcock), a methionine auxotroph. The cytotoxic effects of the heavy metal analogs caused the complete downregulation of various vital proteins, such as: fructose‐bisphosphate aldolase, UPase, phosphoserine aminotransferase, and others. It is hypothesized that through chemically defined media (CDM) supplementation of compounds integral in these downregulated proteins’ pathways, the cytotoxic effects incurred from these heavy metal analogs can be partially alleviated. Compound addition in optimal concentrations should increase overall cell culture growth and positively impact current methodologies pertaining to x‐ray crystallographic analysis.