scholarly journals Identification of a low CO2 responsive mutant from chemical mutagenesis of Setaria viridis shows that reduced carbonic anhydrase severely limits C4 photosynthesis

2021 ◽  
Author(s):  
Jolly Chatterjee ◽  
Robert A Coe ◽  
Kelvin Acebron ◽  
Vivek Thakur ◽  
Ragothaman M Yennamalli ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
C4 Photosynthesis ◽  
Chemical Mutagenesis ◽  
Protein Accumulation ◽  
Setaria Viridis ◽  
Bioinformatics Analyses ◽  
Pep Carboxylase ◽  
Functional Changes ◽  
Low Co2 ◽  
Ca Protein

Abstract In C4 species β-carbonic anhydrase (CA), localized to the cytosol of the mesophyll cells, accelerates the interconversion of CO2 to HCO3  -, the substrate used by PEP carboxylase in the first step of C4 photosynthesis. Here we describe the identification and characterization of a low CO2  responsive mutant 1 (lcr1) isolated from a N-Nitroso-N-methylurea (NMU) treated Setaria viridis mutant population. Forward genetic investigation revealed that the mutated gene Sevir.5G247800 of lcr1 possessed a single nucleotide transition from Cytosine to Thymine in a β-carbonic anhydrase gene causing an amino acid change from Leucine to Phenylalanine. This resulted in severe reduction in growth and photosynthesis in the mutant. Both the CO2 compensation point and carbon isotope discrimination values of the mutant were significantly increased. Growth of the mutants were stunted when grown under ambient pCO2 but recovered at elevated pCO2. Further bioinformatics analyses revealed that the mutation has led to functional changes in one of the conserved residues of the protein, situated near the catalytic site. CA transcript accumulation in the mutant was 80% lower, CA protein accumulation 30% lower and CA activity ~98% lower compared to WT. Changes in the abundance of other primary C4 pathway enzymes were observed; accumulation of PEP carboxylase (PEPC) protein was significantly increased and accumulation of Malate Dehydrogenase (MDH) and Malic Enzyme (ME) decreased. The reduction of CA protein activity and abundance in lcr1 restricts the supply of bicarbonate to PEPC limiting C4 photosynthesis and growth. This study establishes Sevir.5G247800 as the major CA allele in Setaria for C4 photosynthesis and provides important insights into the function of CA in C4 photosynthesis that would be required to generate a rice plant with a functional C4 biochemical pathway.

scholarly journals A Transgenic Approach to Understanding the Influence of Carbonic Anhydrase on C18OO Discrimination during C4 Photosynthesis

2006 ◽  
Vol 142 (2) ◽  
pp. 662-672 ◽  
Author(s):  
Asaph B. Cousins ◽  
Murray R. Badger ◽  
Susanne von Caemmerer
Keyword(s):  
Carbonic Anhydrase ◽  
C4 Photosynthesis

scholarly journals Setaria viridis: A Model for C4 Photosynthesis

2010 ◽  
Vol 22 (8) ◽  
pp. 2537-2544 ◽  
Author(s):  
Thomas P. Brutnell ◽  
Lin Wang ◽  
Kerry Swartwood ◽  
Alexander Goldschmidt ◽  
David Jackson ◽  
...  
Keyword(s):  
C4 Photosynthesis ◽  
Setaria Viridis

scholarly journals Induction and Regulation of Expression of a Low-CO2-Induced Mitochondrial Carbonic Anhydrase inChlamydomonas reinhardtii

1998 ◽  
Vol 116 (2) ◽  
pp. 637-641 ◽  
Author(s):  
Mats Eriksson ◽  
Per Villand ◽  
Per Gardeström ◽  
Göran Samuelsson
Keyword(s):  
Carbonic Anhydrase ◽  
Regulation Of Expression ◽  
Low Co2

scholarly journals Structural insights into the effect of active-site mutation on the catalytic mechanism of carbonic anhydrase

IUCrJ ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 985-994 ◽  
Author(s):  
Jin Kyun Kim ◽  
Cheol Lee ◽  
Seon Woo Lim ◽  
Jacob T. Andring ◽  
Aniruddha Adhikari ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Kinetic Parameters ◽  
Active Site ◽  
Systematic Approach ◽  
Catalytic Mechanism ◽  
Structural Information ◽  
Site Directed Mutagenesis ◽  
Site Mutation ◽  
Functional Changes ◽  
Reaction Rate Constants

Enzymes are catalysts of biological processes. Significant insight into their catalytic mechanisms has been obtained by relating site-directed mutagenesis studies to kinetic activity assays. However, revealing the detailed relationship between structural modifications and functional changes remains challenging owing to the lack of information on reaction intermediates and of a systematic way of connecting them to the measured kinetic parameters. Here, a systematic approach to investigate the effect of an active-site-residue mutation on a model enzyme, human carbonic anhydrase II (CA II), is described. Firstly, structural analysis is performed on the crystallographic intermediate states of native CA II and its V143I variant. The structural comparison shows that the binding affinities and configurations of the substrate (CO2) and product (HCO3 −) are altered in the V143I variant and the water network in the water-replenishment pathway is restructured, while the proton-transfer pathway remains mostly unaffected. This structural information is then used to estimate the modifications of the reaction rate constants and the corresponding free-energy profiles of CA II catalysis. Finally, the obtained results are used to reveal the effect of the V143I mutation on the measured kinetic parameters (k cat and k cat/K m) at the atomic level. It is believed that the systematic approach outlined in this study may be used as a template to unravel the structure–function relationships of many other biologically important enzymes.

scholarly journals Cellular Localization of Carbonic Anhydrase Nce103p in Candida albicans and Candida parapsilosis

2020 ◽  
Vol 21 (3) ◽  
pp. 850
Author(s):  
Jiří Dostál ◽  
Jan Blaha ◽  
Romana Hadravová ◽  
Martin Hubálek ◽  
Olga Heidingsfeld ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Carbonic Anhydrase ◽  
Cellular Localization ◽  
Candida Parapsilosis ◽  
Growth Conditions ◽  
Carbonic Anhydrases ◽  
Atmospheric Conditions ◽  
Low Co2 ◽  
Mitochondrial Fractions

Pathogenic yeasts Candida albicans and Candida parapsilosis possess a ß-type carbonic anhydrase Nce103p, which is involved in CO2 hydration and signaling. C. albicans lacking Nce103p cannot survive in low CO2 concentrations, e.g., in atmospheric growth conditions. Candida carbonic anhydrases are orthologous to the Saccharomyces cerevisiae enzyme, which had originally been detected as a substrate of a non-classical export pathway. However, experimental evidence on localization of C. albicans and C. parapsilosis carbonic anhydrases has not been reported to date. Immunogold labeling and electron microscopy used in the present study showed that carbonic anhydrases are localized in the cell wall and plasmatic membrane of both Candida species. This localization was confirmed by Western blot and mass spectrometry analyses of isolated cell wall and plasma membrane fractions. Further analysis of C. albicans and C. parapsilosis subcellular fractions revealed presence of carbonic anhydrases also in the cytosolic and mitochondrial fractions of Candida cells cultivated in shaken liquid cultures, under the atmospheric conditions.

scholarly journals α1-antitrypsin Deficiency: A Misfolded Secretory Protein Variant with Unique Effects on the Endoplasmic Reticulum

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
David H Perlmutter
Keyword(s):  
Endoplasmic Reticulum ◽  
Liver Disease ◽  
Lung Disease ◽  
Secretory Protein ◽  
Chronic Obstructive ◽  
Protein Accumulation ◽  
Protein Variant ◽  
Obstructive Pulmonary Disease ◽  
Functional Changes ◽  
Antitrypsin Deficiency

AbstractIn the classical form of α1-antitrypsin deficiency (ATD) a point mutation leads to accumulation of a misfolded secretory glycoprotein in the endoplasmic reticulum (ER) of liver cells and so ATD has come to be considered a prototypical ER storage disease . It is associated with two major types of clinical disorders, chronic obstructive pulmonary disease (COPD) by lossof- function mechanisms and hepatic cirrhosis and carcinogenesis by gain-of-function mechanisms. The lung disease predominantly results from proteolytic damage to the pulmonary connective tissue matrix because of reduced levels of protease inhibitor activity of α1-anitrypsin (AT) in the circulating blood and body fluids. Cigarette smoking is a powerful disease-promoting modifier but other modifiers are known to exist because variation in the lung disease phenotype is still found in smoking and non-smoking homozygotes. The liver disease is highly likely to be caused by the proteotoxic effects of intracellular misfolded protein accumulation and a high degree of variation in the hepatic phenotype among affected homozygotes has been hypothetically attributed to genetic and environmental modifiers that alter proteostasis responses. Liver biopsies of homozygotes show intrahepatocytic inclusions with dilation and expansion of the ER and recent studies of iPS-derived hepatocyte-like cells from individuals with ATD indicate that the changes in the ER directly vary with the hepatic phenotype i.e there is much lesser alteration in the ER in cells derived from homozygotes that do not have clinically significant liver disease. From a signaling perspective, studies in mammalian cell line and animal models expressing the classical α1-antitrypsin Z variant (ATZ) have found that ER signaling is perturbed in a relatively unique way with powerful activation of autophagy and the NFκB pathway but relatively limited, if any, UPR signaling. It is still not known how much these unique structural and functional changes and the variation among affected homozygotes relate to the tendency of this variant to polymerize and aggregate and/ or to the repertoire of proteostasis mechanisms that are activated.

Sign in / Sign up

Export Citation Format

Share Document