title: Identification and enzymic analysis of a novel protein associated with production of hydrogen sulfide and L-serine from L-cysteine in Fusobacterium nucleatum subsp. nucleatum ATCC 25586.
abstract: A third enzyme that produces hydrogen sulfide from L-cysteine was identified in Fusobacterium nucleatum subsp. nucleatum. The fn1055 gene was cloned from a cosmid library constructed with genomic DNA of F. nucleatum ATCC 25586. Despite the database annotation that the product of fn1055 is a cysteine synthase, reverse-phase HPLC revealed that no L-cysteine was produced in vitro by the purified Fn1055 protein; however, the enzyme did produce L-serine. In addition, a cysteine auxotroph, Escherichia coli NK3, transformed with a plasmid containing the fn1055 gene did not grow without cysteine, which further suggests that Fn1055 does not function as a cysteine synthase. The Michaelis-Menten kinetics (K(m) =0.09 ± 0.001 mM and k(cat) =5.43 ± 0.64 s(-1)) of the purified enzyme showed that the capacity of Fn1055 to produce hydrogen sulfide was between that of two other enzymes, Fn0625 and Fn1220. Incubation of Fn1055 with L-cysteine resulted in the production of hydrogen sulfide, but not of pyruvate, ammonia or lanthionine, which are all byproducts produced in addition to hydrogen sulfide when Fn0625 or Fn1220 is incubated with L-cysteine. Instead, Fn1055 produced L-serine in its reaction with L-cysteine. Fn1055 produces hydrogen sulfide from l-cysteine by a mechanism that is different from that of Fn0625 or Fn1220.
authors.affiliation: Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Conservative Dentistry and Oral Rehabilitation, School of Dentistry, Iwate Medical University, Morioka, Japan.|Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Suwabe
authors.affiliation: Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Nagano
authors.affiliation: Department of Structural Biology, School of Pharmacy, Iwate Medical University, Yahaba, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kezuka
authors.affiliation: Department of Pathogenesis and Control of Oral Disease, School of Dentistry, Iwate Medical University, Morioka, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Kato
authors.affiliation: Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
authors.forename: Fuminobu
authors.initials: F
authors.lastname: Yoshimura
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000378:metabolism*; D003547:Cysteine Synthase / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D016967:Fusobacterium nucleatum / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D006862:Hydrogen Sulfide / Q000378:metabolism*; D007700:Kinetics; D012694:Serine / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D012694:Serine; D003547:Cysteine Synthase; D003545:Cysteine; D006862:Hydrogen Sulfide