On the influence of cobamides on organohalide respiration and mercury methylation

Corrinoids are metallic cofactors that serve as prosthetic groups for numerous reactions catalyzed by various microorganisms, ranging from carbon and nitrogen cycling to toxic waste remediation. Importantly, the number of organisms that require corrinoids far outweigh that which can produce corrinoid de novo. This imbalance in supply and demand reveals interdependencies at the molecular scale amongst various organisms, where a corrinoid auxotroph may need to coexist with a corrinoid prototroph. A further determinant of corrinoid function lies in the lower base, and essential component of functional corrinoids. In the case of Dehalococcoides mccartyi, studies have shown that differences in lower base structure impact the activity of corrinoid-binding reductive dehalogenase enzymes. This body of work examines a gene from Geobacter lovleyi implicated in the synthesis of the 5-methoxybenzimidazole lower base, and how this lower base may play a role in regulating corrinoid-dependent reactions including reductive dechlorination in Dehalococcoides mccartyi and mercury methylation.