RRC ID 47375
著者 Loganathan N, Tsai YC, Mueller-Cajar O.
タイトル Characterization of the heterooligomeric red-type rubisco activase from red algae.
ジャーナル Proc Natl Acad Sci U S A
Abstract The photosynthetic CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is inhibited by nonproductive binding of its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. Reactivation requires ATP-hydrolysis-powered remodeling of the inhibited complexes by diverse molecular chaperones known as rubisco activases (Rcas). Eukaryotic phytoplankton of the red plastid lineage contain so-called red-type rubiscos, some of which have been shown to possess superior kinetic properties to green-type rubiscos found in higher plants. These organisms are known to encode multiple homologs of CbbX, the α-proteobacterial red-type activase. Here we show that the gene products of two cbbX genes encoded by the nuclear and plastid genomes of the red algae Cyanidioschyzon merolae are nonfunctional in isolation, but together form a thermostable heterooligomeric Rca that can use both α-proteobacterial and red algal-inhibited rubisco complexes as a substrate. The mechanism of rubisco activation appears conserved between the bacterial and the algal systems and involves threading of the rubisco large subunit C terminus. Whereas binding of the allosteric regulator RuBP induces oligomeric transitions to the bacterial activase, it merely enhances the kinetics of ATP hydrolysis in the algal enzyme. Mutational analysis of nuclear and plastid isoforms demonstrates strong coordination between the subunits and implicates the nuclear-encoded subunit as being functionally dominant. The plastid-encoded subunit may be catalytically inert. Efforts to enhance crop photosynthesis by transplanting red algal rubiscos with enhanced kinetics will need to take into account the requirement for a compatible Rca.
巻・号 113(49)
ページ 14019-14024
公開日 2016-12-6
DOI 10.1073/pnas.1610758113
PII 1610758113
PMID 27872295
PMC PMC5150372
MeSH Allosteric Regulation / physiology Kinetics Molecular Chaperones / metabolism Photosynthesis / genetics Photosynthesis / physiology Plant Proteins / genetics Plant Proteins / metabolism* Plastids / genetics Rhodophyta / metabolism* Ribulose-Bisphosphate Carboxylase / antagonists & inhibitors Ribulose-Bisphosphate Carboxylase / metabolism* Ribulosephosphates / metabolism
IF 9.412
引用数 19
WOS 分野 BIOCHEMISTRY & MOLECULAR BIOLOGY
リソース情報
藻類 NIES-1332