Doten R C, Mortlock R P
J Bacteriol. 1985 Feb;161(2):529-33. doi: 10.1128/jb.161.2.529-533.1985.
Of the four pentitols ribitol, xylitol, D-arabitol, and L-arabitol, Erwinia uredovora was able to utilize only D-arabitol as a carbon and energy source. Although attempts to isolate ribitol- or L-arabitol-utilizing mutants were unsuccessful, mutants able to grow on xylitol were isolated at a frequency of 9 X 10(-8). Xylitol-positive mutants constitutively synthesized both a novel NAD-dependent xylitol-4-dehydrogenase, which oxidized xylitol to L-xylulose, and an L-xylulokinase. The xylitol dehydrogenase had a Km for xylitol of 48 mM and showed best activity with xylitol and D-threitol as substrates. However, D-threitol was not a growth substrate for E. uredovora, and its presence did not induce either dehydrogenase or kinase activity. Attempts to determine the origin of the xylitol catabolic enzymes were unsuccessful; neither enzyme was induced on any growth substrate or in the presence of any polyol tested. Analysis of xylitol-negative mutants isolated after Tn5 mutagenesis suggested that the xylitol dehydrogenase and the L-xylulokinase structural genes were components of two separate operons but were under common regulatory control.
在核糖醇、木糖醇、D-阿拉伯糖醇和L-阿拉伯糖醇这四种戊糖醇中，草生欧文氏菌仅能利用D-阿拉伯糖醇作为碳源和能源。虽然分离利用核糖醇或L-阿拉伯糖醇的突变体的尝试未成功，但能在木糖醇上生长的突变体以9×10⁻⁸的频率被分离出来。木糖醇阳性突变体组成型地合成了一种新的依赖NAD的木糖醇-4-脱氢酶，该酶将木糖醇氧化为L-木酮糖，以及一种L-木酮糖激酶。木糖醇脱氢酶对木糖醇的Km值为48 mM，以木糖醇和D-苏糖醇作为底物时表现出最佳活性。然而，D-苏糖醇不是草生欧文氏菌的生长底物，其存在也不会诱导脱氢酶或激酶活性。确定木糖醇分解代谢酶来源的尝试未成功；在任何生长底物上或在任何测试的多元醇存在下，这两种酶都不会被诱导。对Tn5诱变后分离的木糖醇阴性突变体的分析表明，木糖醇脱氢酶和L-木酮糖激酶结构基因是两个独立操纵子的组成部分，但受共同的调控控制。
