title: UDP-galactopyranose mutases from Leishmania species that cause visceral and cutaneous leishmaniasis.
abstract: Leishmaniasis is a vector-borne, neglected tropical disease caused by parasites from the genus Leishmania. Galactofuranose (Galf) is found on the cell surface of Leishmania parasites and is important for virulence. The flavoenzyme that catalyzes the isomerization of UDP-galactopyranose to UDP-Galf, UDP-galactopyranose mutase (UGM), is a validated drug target in protozoan parasites. UGMs from L. mexicana and L. infantum were recombinantly expressed, purified, and characterized. The isolated enzymes contained tightly bound flavin cofactor and were active only in the reduced form. NADPH is the preferred redox partner for both enzymes. A kcat value of 6 ± 0.4s(-1) and a Km value of 252 ± 42 μM were determined for L. infantum UGM. For L. mexicana UGM, these values were ∼4-times lower. Binding of UDP-Galp is enhanced 10-20 fold in the reduced form of the enzymes. Changes in the spectra of the reduced flavin upon interaction with the substrate are consistent with formation of a flavin-iminium ion intermediate.
authors.affiliation: Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, United States.
authors.forename: Isabel O
authors.initials: IO
authors.lastname: Fonseca
authors.forename: Karina
authors.initials: K
authors.lastname: Kizjakina
authors.forename: Pablo
authors.initials: P
authors.lastname: Sobrado
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D005415:Flavins / Q000378:metabolism; D006801:Humans; D019751:Intramolecular Transferases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018314:Leishmania infantum / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D007894:Leishmania mexicana / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology; D007898:Leishmaniasis, Visceral / Q000469:parasitology; D008969:Molecular Sequence Data; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D014774:Virulence
chemical_list: D005415:Flavins; D011994:Recombinant Proteins; D009249:NADP; D019751:Intramolecular Transferases; C098051:UDP-galactopyranose mutase
keywords: Flavin-dependent reaction; Galactofuranose; Neglected diseases; Non-redox reaction