Article

Rubisco: structure, regulatory interactions, and possibilities for a better enzyme.

Department of Biochemistry, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, Nebraska 68588-0664, USA.
Annual review of plant biology (Impact Factor: 18.9). 02/2002; 53:449-75. DOI: 10.1146/annurev.arplant.53.100301.135233
Source: PubMed

ABSTRACT Ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes the first step in net photosynthetic CO2 assimilation and photorespiratory carbon oxidation. The enzyme is notoriously inefficient as a catalyst for the carboxylation of RuBP and is subject to competitive inhibition by O2, inactivation by loss of carbamylation, and dead-end inhibition by RuBP. These inadequacies make Rubisco rate limiting for photosynthesis and an obvious target for increasing agricultural productivity. Resolution of X-ray crystal structures and detailed analysis of divergent, mutant, and hybrid enzymes have increased our insight into the structure/function relationships of Rubisco. The interactions and associations relatively far from the Rubisco active site, including regulatory interactions with Rubisco activase, may present new approaches and strategies for understanding and ultimately improving this complex enzyme.

1 Bookmark
 · 
275 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Stipa purpurea, an endemic forage species on the Tibetan Plateau, is highly resistant to cold and drought, but the mechanisms underlying its responses to drought stress remain elusive. An understanding of such mechanisms may be useful for developing cultivars that are adaptable to water deficit. In this study, we analyzed the physiological and proteomic responses of S. purpurea under increasing drought stress. Seedlings of S. purpurea were subjected to a drought gradient in a controlled experiment, and proteins showing changes in abundance under these conditions were identified by two-dimensional electrophoresis followed by mass spectrometry analysis. A western blotting analysis was conducted to confirm the increased abundance of a heat-shock protein, NCED2, and a dehydrin in S. purpurea seedlings under drought conditions. We detected carbonylated proteins to identify oxidation-sensitive proteins in S. purpurea seedlings, and found that ribulose-1, 5-bisphosphate carboxylase oxygenase (RuBisCO) was one of the oxidation-sensitive proteins under drought. Together, these results indicated drought stress might inhibit photosynthesis in S. purpurea by oxidizing RuBisCO, but the plants were able to maintain photosynthetic efficiency by a compensatory upregulation of unoxidized RuBisCO and other photosynthesis-related proteins. Further analyses confirmed that increased abundance of antioxidant enzymes could balance the redox status of the plants to mitigate drought-induced oxidative damage.
    PLoS ONE 02/2015; 10(2):e0117475. DOI:10.1371/journal.pone.0117475 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is a crucial enzyme catalyzing the CO2-fixing reaction in the initial step of the Calvin cycle. In this study, the full-length cDNA of Rubisco large subunit (RbcL) from the bloom-forming green alga Chaetomorpha valida (designated as CvRbcL) was isolated based on homologous cloning and the rapid amplification of cDNA ends (RACE) (accession: KF514135). It was 1,966-bp long, with an open reading frame of 1,431 bp without intron. The deduced 476 amino acids gave a predicted molecular weight of 52.38 kDa and theoretical isoelectric point of 6.15. Three catalytic regions and a CO2 activator region were identified in the CvRbcL, which highly conserved with those of other green algae and higher plants. Homologous analysis indicated that CvRbcL shared 52–86 % similarities with other 13 known algal and higher plant RbcLs sequences. Phylogenetic analysis showed that it had closer relationship with those of green algae and higher plants but was comparatively far from the red and brown algae clade. Real-time PCR detection revealed that the CvRbcL expression were dramatically upregulated by light and strongly suppressed in the dark. Temperature also markedly affected the CvRbcL transcription. A relatively high transcript level appeared between 15–25 °C and reached the maximum at 20 °C. This indirectly reflected that highly expressed Rubisco was involved with CO2 metabolism of C. valida under favorable natural environments, and might contribute to its fast growth and bloom formation. In vitro expression of CvRbcL showed that one distinct band existed at ∼55 kDa, and western blot detection proved that it was positive to the anti-His antibody with high specificity. Our study is the first to characterize RbcL gene from Chaetomorpha species providing more knowledge of RbcL properties and facilitating further exploration of Rubisco in green macroalgae. Our results also help to decipher Rubisco molecular functions in the rapid growth period of C. valida and provide clues to develop forecasts of the seasonal C. valida bloom.
    Journal of Applied Phycology 08/2013; 26(4):1853-1861. DOI:10.1007/s10811-013-0208-z · 2.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To examine the interactions of starch and sugar metabolism on photosynthesis in cassava, a heat-girdling treatment was applied to petioles of cassava leaves at the end of the light cycle to inhibit starch remobilization during the night. The inhibition of starch remobilization caused significant starch accumulation at the beginning of the light cycle, inhibited photosynthesis, and affected intracellular sugar levels. RNA-seq analysis of heat-treated and control plants revealed significantly decreased expression of genes related to photosynthesis, as well as N-metabolism and chlorophyll biosynthesis. However, expression of genes encoding TCA cycle enzymes and mitochondria electron transport components, and flavonoid biosynthetic pathway enzymes were induced. These studies reveal a dynamic transcriptional response to perturbation of sink demand in a single leaf, and provide useful information for understanding the regulations of cassava under sink or source limitation.

Full-text (2 Sources)

Download
374 Downloads
Available from
May 20, 2014