title: Drosophila selenophosphate synthetase 1 regulates vitamin B6 metabolism: prediction and confirmation.
abstract: BACKGROUND
  There are two selenophosphate synthetases (SPSs) in higher eukaryotes, SPS1 and SPS2. Of these two isotypes, only SPS2 catalyzes selenophosphate synthesis. Although SPS1 does not contain selenophosphate synthesis activity, it was found to be essential for cell growth and embryogenesis in Drosophila. The function of SPS1, however, has not been elucidated.
  
  
  RESULTS
  Differentially expressed genes in Drosophila SL2 cells were identified using two-way analysis of variance methods and clustered according to their temporal expression pattern. Gene ontology analysis was performed against differentially expressed genes and gene ontology terms related to vitamin B6 biosynthesis were found to be significantly affected at the early stage at which megamitochondria were not formed (day 3) after SPS1 knockdown. Interestingly, genes related to defense and amino acid metabolism were affected at a later stage (day 5) following knockdown. Levels of pyridoxal phosphate, an active form of vitamin B6, were decreased by SPS1 knockdown. Treatment of SL2 cells with an inhibitor of pyridoxal phosphate synthesis resulted in both a similar pattern of expression as that found by SPS1 knockdown and the formation of megamitochondria, the major phenotypic change observed by SPS1 knockdown.
  
  
  CONCLUSIONS
  These results indicate that SPS1 regulates vitamin B6 synthesis, which in turn impacts various cellular systems such as amino acid metabolism, defense and other important metabolic activities.
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea.
authors.forename: Kwang Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Myoung Sup
authors.initials: MS
authors.lastname: Shim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Hee Kyoung
authors.initials: HK
authors.lastname: Jung
authors.forename: Eunji
authors.initials: E
authors.lastname: Lee
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Carlson
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Xu
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Park
authors.forename: Dolph L
authors.initials: DL
authors.lastname: Hatfield
authors.forename: Taesung
authors.initials: T
authors.lastname: Park
authors.forename: Byeong Jae
authors.initials: BJ
authors.lastname: Lee
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004330:Drosophila / Q000201:enzymology* / Q000235:genetics; D029721:Drosophila Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D025101:Vitamin B 6 / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D034741:RNA, Small Interfering; D011732:Pyridoxal Phosphate; D025101:Vitamin B 6; D010770:Phosphotransferases; C109636:sps1 protein, Drosophila