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J Biol Chem. 2012 Nov 23;287(48):40448-56. doi: 10.1074/jbc.M112.403055. Epub 2012 Oct 4.

An L-glucose catabolic pathway in Paracoccus species 43P.

Author information

1
Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.

Abstract

BACKGROUND:

L-Glucose, the enantiomer of D-glucose, was believed not to be utilized by any organisms.

RESULTS:

An L-glucose-utilizing bacterium was isolated, and its L-glucose catabolic pathway was identified genetically and enzymatically.

CONCLUSION:

L-Glucose was utilized via a novel pathway to pyruvate and D-glyceraldehyde 3-phosphate.

SIGNIFICANCE:

This might lead to an understanding of homochirality in sugar metabolism. An L-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.

PMID:
23038265
PMCID:
PMC3504760
DOI:
10.1074/jbc.M112.403055
[Indexed for MEDLINE]
Free PMC Article
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