3HJZ

The structure of an aldolase from Prochlorococcus marinus

3HJZ の概要

• エントリーDOI: 10.2210/pdb3hjz/pdb
• 分子名称: Transaldolase B, 1,2-ETHANEDIOL, SODIUM ION, ... (7 entities in total)
• 機能のキーワード: transaldolase, parachlorococcus, marine, cyanobacteria, fructose-6-phosphate erythrose-4-phosphate sedoheptulose-7-phosphate glyceraldehyde-3-phosphate, structural genomics, psi-2, protein structure initiative, midwest center for structural genomics, mcsg, pentose shunt, transferase
• 由来する生物種: Prochlorococcus marinus str. MIT 9312
• 細胞内の位置: Cytoplasm (By similarity): Q31C15
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 38496.48

構造登録者

Singer, A.U.,Xu, X.,Cui, H.,Joachimiak, A.,Edwards, A.M.,Savchenko, A.,Midwest Center for Structural Genomics (MCSG) (登録日: 2009-05-22, 公開日: 2009-06-09, 最終更新日: 2024-11-20)

主引用文献

Thompson, L.R.,Zeng, Q.,Kelly, L.,Huang, K.H.,Singer, A.U.,Stubbe, J.,Chisholm, S.W.
Phage auxiliary metabolic genes and the redirection of cyanobacterial host carbon metabolism.
Proc.Natl.Acad.Sci.USA, 108:E757-E764, 2011

PubMed Abstract: Cyanophages infecting the marine cyanobacteria Prochlorococcus and Synechococcus encode and express genes for the photosynthetic light reactions. Sequenced cyanophage genomes lack Calvin cycle genes, however, suggesting that photosynthetic energy harvested via phage proteins is not used for carbon fixation. We report here that cyanophages carry and express a Calvin cycle inhibitor, CP12, whose host homologue directs carbon flux from the Calvin cycle to the pentose phosphate pathway (PPP). Phage CP12 was coexpressed with phage genes involved in the light reactions, deoxynucleotide biosynthesis, and the PPP, including a transaldolase gene that is the most prevalent PPP gene in cyanophages. Phage transaldolase was purified to homogeneity from several strains and shown to be functional in vitro, suggesting that it might facilitate increased flux through this key reaction in the host PPP, augmenting production of NADPH and ribose 5-phosphate. Kinetic measurements of phage and host transaldolases revealed that the phage enzymes have k(cat)/K(m) values only approximately one third of the corresponding host enzymes. The lower efficiency of phage transaldolase may be a tradeoff for other selective advantages such as reduced gene size: we show that more than half of host-like cyanophage genes are significantly shorter than their host homologues. Consistent with decreased Calvin cycle activity and increased PPP and light reaction activity under infection, the host NADPH/NADP ratio increased two-fold in infected cells. We propose that phage-augmented NADPH production fuels deoxynucleotide biosynthesis for phage replication, and that the selection pressures molding phage genomes involve fitness advantages conferred through mobilization of host energy stores.

PubMed: 21844365
DOI: 10.1073/pnas.1102164108

実験手法

X-RAY DIFFRACTION (1.9 Å)