AtTHIC, a gene involved in thiamine biosynthesis in Arabidopsis thaliana

• 来源期刊: 细胞研究（英文版）
• 年，卷（期）: 2008,（5）
• 页码范围: 566-576
• 页数: 11页
• 语种: 英文

摘要

Thiamine (vitamin B1) 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 coil ThiC,which is involved in pyrimidine biosynthesis in prokaryotes.Heterologous expression of AtTHIC could functionally complement the thiC knock-out mutant of E.coll.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 thicl showed albino (white leaves) and lethal phenotypes under the normal culture conditions.The thicl mutant could be rescued by supplementation of thiamine and its defect functions could be complemented by expression ofAtTHIC 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.