title: AtTHIC, a gene involved in thiamine biosynthesis in Arabidopsis thaliana.
abstract: Thiamine (vitamin B(1)) is an essential compound for organisms. It contains a pyrimidine ring structure and a thiazole ring structure. These two moieties of thiamine are synthesized independently and then coupled together. Here we report the molecular characterization of AtTHIC, which is involved in thiamine biosynthesis in Arabidopsis. AtTHIC is similar to Escherichia coli ThiC, which is involved in pyrimidine biosynthesis in prokaryotes. Heterologous expression of AtTHIC could functionally complement the thiC knock-out mutant of E. coli. Downregulation of AtTHIC expression by T-DNA insertion at its promoter region resulted in a drastic reduction of thiamine content in plants and the knock-down mutant thic1 showed albino (white leaves) and lethal phenotypes under the normal culture conditions. The thic1 mutant could be rescued by supplementation of thiamine and its defect functions could be complemented by expression of AtTHIC cDNA. Transient expression analysis revealed that the AtTHIC protein targets plastids and chloroplasts. AtTHIC was strongly expressed in leaves, flowers and siliques and the transcription of AtTHIC was downregulated by extrinsic thiamine. In conclusion, AtTHIC is a gene involved in pyrimidine synthesis in the thiamine biosynthesis pathway of Arabidopsis, and our results provide some new clues for elucidating the pathway of thiamine biosynthesis in plants.
authors.affiliation: The State Key Laboratory of Plant Cell and Chromosome Engineering, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China.
authors.forename: Danyu
authors.initials: D
authors.lastname: Kong
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Zhu
authors.forename: Huilan
authors.initials: H
authors.lastname: Wu
authors.forename: Xudong
authors.initials: X
authors.lastname: Cheng
authors.forename: Hui
authors.initials: H
authors.lastname: Liang
authors.forename: Hong-Qing
authors.initials: HQ
authors.lastname: Ling
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern; D011756:Diphosphates / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005816:Genetic Complementation Test; D007506:Iron-Sulfur Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013831:Thiamine / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D029681:Arabidopsis Proteins; D011756:Diphosphates; D007506:Iron-Sulfur Proteins; C525883:THIC protein, Arabidopsis; D013831:Thiamine