Metabolism of sugars by genetically diverse species of oral Leptotrichia

Mol Oral Microbiol. 2012 Feb;27(1):34-44. doi: 10.1111/j.2041-1014.2011.00627.x. Epub 2011 Oct 4.


Leptotrichia buccalis ATCC 14201 is a gram-negative, anaerobic rod-shaped bacterium resident in oral biofilm at the tooth surface. The sequenced genome of this organism reveals three contiguous genes at loci: Lebu_1525, Lebu_1526 and Lebu_1527. The translation products of these genes exhibit significant homology with phospho-α-glucosidase (Pagl), a regulatory protein (GntR) and a phosphoenol pyruvate-dependent sugar transport protein (EIICB), respectively. In non-oral bacterial species, these genes comprise the sim operon that facilitates sucrose isomer metabolism. Growth studies showed that L. buccalis fermented a wide variety of carbohydrates, including four of the five isomers of sucrose. Growth on the isomeric disaccharides elicited expression of a 50-kDa polypeptide comparable in size to that encoded by Lebu_1525. The latter gene was cloned, and the expressed protein was purified to homogeneity from Escherichia coli TOP10 cells. In the presence of two cofactors, NAD(+) and Mn(2+) ions, the enzyme readily hydrolyzed p-nitrophenyl-α-glucopyranoside 6-phosphate (pNPαG6P), a chromogenic analogue of the phosphorylated isomers of sucrose. By comparative sequence alignment, immunoreactivity and signature motifs, the enzyme can be assigned to the phospho-α-glucosidase (Pagl) clade of Family 4 of the glycosyl hydrolase super family. We suggest that the products of Lebu_1527 and Lebu_1525, catalyze the phosphorylative translocation and hydrolysis of sucrose isomers in L. buccalis, respectively. Four genetically diverse, but 16S rDNA-related, species of Leptotrichia have recently been described: L. goodfellowii, L. hofstadii, L. shahii and L. wadei. The phenotypic traits of these new species, with respect to carbohydrate utilization, have also been determined.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Bacterial Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Dental Plaque / microbiology
  • Disaccharidases / metabolism*
  • Genes, Bacterial
  • Glycoside Hydrolases / genetics
  • Isoenzymes
  • Leptotrichia / genetics*
  • Leptotrichia / metabolism*
  • Monosaccharide Transport Proteins / metabolism
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • Phosphorylation / genetics
  • Species Specificity
  • Sucrose / metabolism*
  • alpha-Glucosidases / genetics


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Isoenzymes
  • Monosaccharide Transport Proteins
  • Sucrose
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • Disaccharidases
  • Glycoside Hydrolases
  • alpha-Glucosidases