myo-Inositol dehydrogenase and scyllo-inositol dehydrogenase from Lactobacillus casei BL23 bind their substrates in very different orientations

Preparation and Application of 13C-Labeled myo-Inositol to Identify New Catabolic Products in Inositol Metabolism in Lactobacillus casei

“…The high-resolution structure of sIDH in complex with scyllo -inositol shows the substrate bound in its lowest-energy chair conformation, indicating that the enzyme catalyzes hydride transfer from a carbon bearing an equatorial hydroxyl group . Therefore, we predicted that oxidation of mI might occur at any of the equatorial positions, but likely not at C-2.…”

“…These studies indicated that mI dehydrogenase (mIDH) catalyzes the first step in mI catabolism by selectively oxidizing the hydroxyl group at position 2 forming scyllo -inosose (Figure ). We also found that the iol operon encoding mIDH also encodes a scyllo -inositol dehydrogenase (sIDH) that oxidizes the less abundant scyllo -inositol . Although most iol gene product functions have been determined, studies have shown some differences in gene cluster organization and enzyme specificity .…”

“…We have studied the enzymes in inositol catabolism of two Gram-positive bacteria, B. subtilis , and Lactobacillus casei . These studies indicated that mI dehydrogenase (mIDH) catalyzes the first step in mI catabolism by selectively oxidizing the hydroxyl group at position 2 forming scyllo -inosose (Figure ).…”

“…This demonstrated that sIDH is a nonselective dehydrogenase, and therefore, predicting the products of the oxidation is challenging. Crystal structures of sIDH in the ternary complex with NAD + and scyllo -inositol suggested that the enzyme prefers oxidizing equatorial hydroxyl groups . Thus, we were particularly interested in investigating the sIDH-catalyzed oxidation position or positions in the more abundant mI, revealing additional relevant catabolic products.…”

Alone at last! – Heterologous expression of a single gene is sufficient for establishing the five-step Weimberg pathway in Corynebacterium glutamicum

“…In case of Pseudomonas sp., it could be demonstrated that the periplasmic glucose dehydrogenase (Gcd) also contributes to d -xylose utilization via the Weimberg pathway (Köhler et al., 2015; Meijnen et al., 2009). Similarly, an enzymatic study not directly connected to growth on d -xylose revealed that the two endogenous myo -inositol dehydrogenases IolG1 and IolG2 of Lactobacillus casei BL23 can convert d -xylose to d -xylonate similar to IolG of C. glutamicum (Aamudalapalli et al., 2018).…”