Crystal structure of l-threonine-O-3-phosphate decarboxylase CobC from Sinorhizobium meliloti involved in vitamin B 12 biosynthesis.

Vitamin B ₁₂ is involved in many important biochemical reactions for humans, and its deficiency can lead to serious diseases. The industrial production of vitamin B ₁₂ is achieved through microbial fermentation. In this work, we determine the crystal structures of the l-threonine-O-3-phosphate (Thr-P) decarboxylase CobC from Sinorhizobium meliloti (SmCobC), an industrial vitamin B ₁₂ -producing bacterium, in apo form and in complex with a reaction intermediate. Our structures supported the Thr-P decarboxylase activity of SmCobC and revealed that the positively charged substrate-binding pocket between the large and small domains determines its substrate selectivity for Thr-P. Moreover, our results provided evidence for the proposition that the AP-P linker is formed by direct incorporation of AP-P in the biosynthetic pathway of vitamin B ₁₂ in S.meliloti.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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