An L-glucose Catabolic Pathway in Paracoccus Species 43P
An L-glucose Catabolic Pathway in Paracoccus Species 43P
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DOI：
10.1074/jbc.m112.403055
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发表时间：
2012-11-23
影响因子：
4.8
通讯作者：
Nakamura, Akira
中科院分区：
文献类型：
--
作者：
Shimizu, Tetsu;Takaya, Naoki;Nakamura, Akira
以L-葡萄糖为唯一碳源，采用富集培养法从土壤中分离到一株L-葡萄糖利用菌Paracoccus sp.43P。在该细菌的无细胞提取物中，检测到NAD（+）依赖性L-葡萄糖脱氢酶对L-葡萄糖具有唯一活性。这种酶，LgdA，纯化，并发现lgdA基因位于一个集群的推定肌醇分解代谢基因。LgdA对鲨肌醇和肌肌醇表现出相似的脱氢酶活性。在无细胞提取物中也检测到L-葡萄糖酸脱氢酶活性，其代表LgdA活性对L-葡萄糖的反应产物。酶纯化和基因克隆显示，相应的基因位于一个九基因簇，lgn簇，这可能参与了醛糖掺入和同化。在集群中的每个基因产物的动力学和反应产物分析表明，他们依次代谢L-葡萄糖酸糖酵解中间体，D-甘油醛-3-磷酸，丙酮酸通过C-5差向异构化反应的脱氢酶/还原酶，脱水，磷酸化，和醛缩酶反应，使用类似的途径L-半乳糖酸催化剂在大肠杆菌。基因破坏研究表明，所识别的基因负责L-葡萄糖分解代谢。
AnL-glucose-utilizing bacterium, Paracoccus sp. 43P, was isolated from soil by enrichment cultivation in a minimal medium containing L-glucose as the sole carbon source. In cell-free extracts from this bacterium, NAD(+)-dependent L-glucose dehydrogenase was detected as having sole activity toward L-glucose. This enzyme, LgdA, was purified, and the lgdA gene was found to be located in a cluster of putative inositol catabolic genes. LgdA showed similar dehydrogenase activity toward scyllo-and myo-inositols. L-Gluconate dehydrogenase activity was also detected in cell-free extracts, which represents the reaction product of LgdA activity toward L-glucose. Enzyme purification and gene cloning revealed that the corresponding gene resides in a nine-gene cluster, the lgn cluster, which may participate in aldonate incorporation and assimilation. Kinetic and reaction product analysis of each gene product in the cluster indicated that they sequentially metabolize L-gluconate to glycolytic intermediates, D-glyceraldehyde-3-phosphate, and pyruvate through reactions of C-5 epimerization by dehydrogenase/reductase, dehydration, phosphorylation, and aldolase reaction, using a pathway similar to L-galactonate catabolism in Escherichia coli. Gene disruption studies indicated that the identified genes are responsible for L-glucose catabolism.