title: A novel glucose 6-phosphate isomerase from Listeria monocytogenes.
abstract: D-Arabinose 5-phosphate isomerases (APIs) catalyze the interconversion of D-ribulose 5-phosphate and D-arabinose 5-phosphate (A5P). A5P is an intermediate in the biosynthesis of 3-deoxy-D-manno-octulosonate (Kdo), an essential component of lipopolysaccharide, the lipopolysaccharide found in the outer membrane of Gram-negative bacteria. The genome of the Gram-positive pathogen Listeria monocytogenes contains a gene encoding a putative sugar isomerase domain API, Q723E8, with significant similarity to c3406, the only one of four APIs from Escherichia coli CFT073 that lacks a cystathionine-β-synthase domain. However, L. monocytogenes lacks genes encoding any of the other enzymes of the Kdo biosynthesis pathway. Realizing that the discovery of an API in a Gram-positive bacterium could provide insight into an alternate physiological role of A5P in the cell, we prepared and purified recombinant Q723E8. We found that Q723E8 does not possess API activity, but instead is a novel GPI (D-glucose 6-phosphate isomerase). However, the GPI activity of Q723E8 is weak compared with previously described GPIS. L. monocytogenes contains an ortholog of the well-studied two-domain bacterial GPI, so this maybe redundant. Based on this evidence glucose utilization is likely not the primary physiological role of Q723E8.
authors.affiliation: Department of Medicinal Chemistry, University of Michigan, 428 Church Street, Ann Arbor, MI, 48109-1065, USA, cechd@umich.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Cech
authors.forename: Pan-Fen
authors.initials: PF
authors.lastname: Wang
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Holt
authors.forename: Victoria A
authors.initials: VA
authors.lastname: Assimon
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Schaub
authors.forename: Tod P
authors.initials: TP
authors.lastname: Holler
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Woodard
mesh_terms: D019747:Aldose-Ketose Isomerases; D000595:Amino Acid Sequence; D029968:Escherichia coli Proteins; D005956:Glucose-6-Phosphate Isomerase / Q000737:chemistry* / Q000378:metabolism*; D008089:Listeria monocytogenes / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D019747:Aldose-Ketose Isomerases; C477520:D-arabinose 5-phosphate isomerase, E coli; D005956:Glucose-6-Phosphate Isomerase