Cech David L, Markin Katherine, Woodard Ronald W
Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA.
J Bacteriol. 2017 Aug 8;199(17). doi: 10.1128/JB.00246-17. Print 2017 Sep 1.
d-Arabinose-5-phosphate (A5P) isomerases (APIs) catalyze the interconversion of d-ribulose-5-phosphate and d-arabinose-5-phosphate. Various Gram-negative bacteria, such as the uropathogenic strain CFT073, contain multiple API paralogs (KdsD, GutQ, KpsF, and c3406) that have been assigned various cellular functions. The d-arabinose-5-phosphate formed by these enzymes seems to play important roles in the biosynthesis of lipopolysaccharide (LPS) and group 2 K-antigen capsules, as well as in the regulation of the cellular d-glucitol uptake and uropathogenic infectivity/virulence. The genome of a Gram-positive pathogenic bacterium, , contains a gene encoding a putative API, API (CtAPI), even though lacks both LPS and capsid biosynthetic genes. To better understand the physiological role of d-arabinose-5-phosphate in this Gram-positive organism, recombinant CtAPI was purified and characterized. CtAPI displays biochemical characteristics similar to those of APIs from Gram-negative organisms and complements the API deficiency of an API knockout strain. Thus, CtAPI represents the first d-arabinose-5-phosphate isomerase to be identified and characterized from a Gram-positive bacterium. The genome of , a pathogenic Gram-positive bacterium and the causative agent of tetanus, contains a gene (the CtAPI gene) that shares high sequence similarity with those of genes encoding d-arabinose-5-phosphate isomerases. APIs play an important role within Gram-negative bacteria in d-arabinose-5-phosphate production for lipopolysaccharide biosynthesis, capsule formation, and regulation of cellular d-glucitol uptake. The significance of our research is in identifying and characterizing CtAPI, the first Gram-positive API. Our findings show that CtAPI is specific to the interconversion of arabinose-5-phosphate and ribulose-5-phosphate while having no activity with the other sugars and sugar phosphates tested. We have speculated a regulatory role for this API in , an organism that does not produce lipopolysaccharide.
D-阿拉伯糖-5-磷酸（A5P）异构酶（APIs）催化D-核酮糖-5-磷酸和D-阿拉伯糖-5-磷酸之间的相互转化。多种革兰氏阴性菌，如尿路致病性菌株CFT073，含有多个API旁系同源物（KdsD、GutQ、KpsF和c3406），它们被赋予了各种细胞功能。这些酶形成的D-阿拉伯糖-5-磷酸似乎在脂多糖（LPS）和2型K抗原荚膜的生物合成中，以及在细胞D-葡萄糖醇摄取和尿路致病性感染性/毒力的调节中发挥重要作用。一种革兰氏阳性致病细菌的基因组包含一个编码假定API（CtAPI）的基因，尽管该细菌缺乏LPS和衣壳生物合成基因。为了更好地理解D-阿拉伯糖-5-磷酸在这种革兰氏阳性生物体中的生理作用，对重组CtAPI进行了纯化和表征。CtAPI表现出与革兰氏阴性生物体的APIs相似的生化特性，并弥补了API基因敲除菌株的API缺陷。因此，CtAPI是第一个从革兰氏阳性细菌中鉴定和表征的D-阿拉伯糖-5-磷酸异构酶。破伤风致病革兰氏阳性细菌的基因组包含一个与编码D-阿拉伯糖-5-磷酸异构酶的基因具有高度序列相似性的基因（CtAPI基因）。APIs在革兰氏阴性细菌中对脂多糖生物合成、荚膜形成以及细胞D-葡萄糖醇摄取的调节中的D-阿拉伯糖-5-磷酸产生中起重要作用。我们研究的意义在于鉴定和表征第一个革兰氏阳性API CtAPI。我们的研究结果表明，CtAPI对阿拉伯糖-5-磷酸和核酮糖-5-磷酸的相互转化具有特异性，而对测试的其他糖类和糖磷酸酯没有活性。我们推测这种API在不产生脂多糖的生物体中具有调节作用。
