title: Salvage of the thiamin pyrimidine moiety by plant TenA proteins lacking an active-site cysteine.
abstract: The TenA protein family occurs in prokaryotes, plants and fungi; it has two subfamilies, one (TenA_C) having an active-site cysteine, the other (TenA_E) not. TenA_C proteins participate in thiamin salvage by hydrolysing the thiamin breakdown product amino-HMP (4-amino-5-aminomethyl-2-methylpyrimidine) to HMP (4-amino-5-hydroxymethyl-2-methylpyrimidine); the function of TenA_E proteins is unknown. Comparative analysis of prokaryote and plant genomes predicted that (i) TenA_E has a salvage role similar to, but not identical with, that of TenA_C and (ii) that TenA_E and TenA_C also have non-salvage roles since they occur in organisms that cannot make thiamin. Recombinant Arabidopsis and maize TenA_E proteins (At3g16990, GRMZM2G080501) hydrolysed amino-HMP to HMP and, far more actively, hydrolysed the N-formyl derivative of amino-HMP to amino-HMP. Ablating the At3g16990 gene in a line with a null mutation in the HMP biosynthesis gene ThiC prevented its rescue by amino-HMP. Ablating At3g16990 in the wild-type increased sensitivity to paraquat-induced oxidative stress; HMP overcame this increased sensitivity. Furthermore, the expression of TenA_E and ThiC genes in Arabidopsis and maize was inversely correlated. These results indicate that TenA_E proteins mediate amidohydrolase and aminohydrolase steps in the salvage of thiamin breakdown products. As such products can be toxic, TenA_E proteins may also pre-empt toxicity.
authors.affiliation: *Microbiology and Cell Science Department, University of Florida, Gainesville, FL 32611, U.S.A.
authors.forename: Rémi
authors.initials: R
authors.lastname: Zallot
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, U.S.A.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Yazdani
authors.affiliation: ‡Department of Botany and Plant Pathology, Oregon State University, Hermiston, OR 97838, U.S.A.
authors.forename: Aymeric
authors.initials: A
authors.lastname: Goyer
authors.affiliation: §Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ziemak
authors.affiliation: §Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A.
authors.forename: Jiahn-Chou
authors.initials: JC
authors.lastname: Guan
authors.affiliation: §Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A.
authors.forename: Donald R
authors.initials: DR
authors.lastname: McCarty
authors.affiliation: *Microbiology and Cell Science Department, University of Florida, Gainesville, FL 32611, U.S.A.
authors.forename: Valérie
authors.initials: V
authors.lastname: de Crécy-Lagard
authors.affiliation: ∥Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439, U.S.A.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Gerdes
authors.affiliation: ¶College of Medicine, University of Florida, Gainesville, FL 32610, U.S.A.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Garrett
authors.affiliation: **Department of Biological Sciences and Northeast Structural Genomics Consortium, Columbia University, New York, NY 10027, U.S.A.
authors.forename: Jordi
authors.initials: J
authors.lastname: Benach
authors.affiliation: **Department of Biological Sciences and Northeast Structural Genomics Consortium, Columbia University, New York, NY 10027, U.S.A.
authors.forename: John F
authors.initials: JF
authors.lastname: Hunt
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, U.S.A.
authors.forename: David K
authors.initials: DK
authors.lastname: Shintani
authors.affiliation: §Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hanson
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D006540:Herbicides / Q000494:pharmacology; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D010269:Paraquat / Q000494:pharmacology; D013831:Thiamine / Q000235:genetics / Q000378:metabolism*; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics
chemical_list: C495396:3g16990 protein, Arabidopsis; D029681:Arabidopsis Proteins; D006540:Herbicides; D007506:Iron-Sulfur Proteins; C525883:THIC protein, Arabidopsis; D006867:Hydrolases; C022731:thiaminase II; D010269:Paraquat; D013831:Thiamine