scholarly journals The Rice Plastidial Phosphorylase Participates Directly In Both Sink And Source Processes

2020 ◽  
Author(s):  
Kaan Koper ◽  
Seon-Kap Hwang ◽  
Magnus Wood ◽  
Salvinder Singh ◽  
Asaph Cousins ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrometry Analysis ◽  
Starch Phosphorylase ◽  
Higher Plant ◽  
Dual Roles ◽  
Terminal Electron Acceptor ◽  
Spectrometry Analysis ◽  
Rice Mutant ◽  
Blue Native ◽  
Source And Sink

AbstractA distinctive structural feature of the higher plant plastidial starch phosphorylase (Pho1) is a 50 to 82 amino acid long peptide (L50 - L82), which is absent in phosphorylases from non-plant organisms. To study the function of the rice Pho1 L80 peptide, we complemented a pho1− rice mutant (BMF136) with the wildtype Pho1 gene or with a Pho1 gene lacking the L80 region (Pho1ΔL80). While expression of Pho1 in BMF136 restored normal wildtype phenotype, the introduction of Pho1ΔL80 enhanced growth rate and plant productivity above wildtype levels. Mass spectrometry analysis of proteins captured by anti-Pho1 showed the surprising presence of PsaC, the terminal electron acceptor/donor subunit of photosystem I (PSI). This unexpected interaction was substantiated by reciprocal immobilized protein pulldown assays of seedling extracts and supported by the presence of Pho1 on isolated PSI complexes resolved by blue native gels. Spectrophotometric studies showed that Pho1ΔL80 plants exhibited modified PSI and enhanced CO2 assimilation properties. Collectively, these findings indicate that the higher plant Pho1 has dual roles as a potential modulator of source and sink processes.

scholarly journals The Rice Plastidial Phosphorylase Participates Directly in Both Sink and Source Processes

2020 ◽  
Author(s):  
Kaan Koper ◽  
Seon-Kap Hwang ◽  
Magnus Wood ◽  
Salvinder Singh ◽  
Asaph Cousins ◽  
...  
Keyword(s):  
Co2 Assimilation ◽  
Mass Spectrometry Analysis ◽  
Wild Type ◽  
Starch Phosphorylase ◽  
Higher Plant ◽  
Dual Roles ◽  
Terminal Electron Acceptor ◽  
Spectrometry Analysis ◽  
Rice Mutant ◽  
Wild Type Phenotype

Abstract The plastidial starch phosphorylase (Pho1) functions in starch metabolism. A distinctive structural feature of the higher Pho1 is a 50–82-amino-acid long peptide (L50–L82), which is absent in phosphorylases from non-plant organisms. To study the function of the rice Pho1 L80 peptide, we complemented a pho1− rice mutant (BMF136) with the wild-type Pho1 gene or with a Pho1 gene lacking the L80 region (Pho1ΔL80). While expression of Pho1 in BMF136 restored normal wild-type phenotype, the introduction of Pho1ΔL80 enhanced the growth rate and plant productivity above wild-type levels. Mass spectrometry analysis of proteins captured by anti-Pho1 showed the surprising presence of PsaC, the terminal electron acceptor/donor subunit of photosystem I (PSI). This unexpected interaction was substantiated by reciprocal immobilized protein pull-down assays of seedling extracts and supported by the presence of Pho1 on isolated PSI complexes resolved by blue-native gels. Spectrophotometric studies showed that Pho1ΔL80 plants exhibited modified PSI and enhanced CO2 assimilation properties. Collectively, these findings indicate that the higher plant Pho1 has dual roles as a potential modulator of source and sink processes.

scholarly journals Effect of Ocular Hypertension on D-β-Aspartic Acid-Containing Proteins in the Retinas of Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Takashi Kanamoto ◽  
Takashi Tachibana ◽  
Yasushi Kitaoka ◽  
Toshio Hisatomi ◽  
Yasuhiro Ikeda ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ocular Hypertension ◽  
Aspartic Acid ◽  
Atp Synthase ◽  
Wistar Rats ◽  
Protein Band ◽  
Mass Spectrometry Analysis ◽  
Liquid Chromatography Mass Spectrometry ◽  
Spectrometry Analysis ◽  
Sds Page

Purpose. To investigate the effect of ocular hypertension-induced isomerization of aspartic acid in retinal proteins. Methods. Adult Wistar rats with ocular hypertension were used as an experimental model. D-β-aspartic acid-containing proteins were isolated by SDS-PAGE and western blot with an anti-D-β-aspartic acid antibody and identified by liquid chromatography-mass spectrometry analysis. The concentration of ATP was measured by ELISA. Results. D-β-aspartic acid was expressed in a protein band at around 44.5 kDa at much higher quantities in the retinas of rats with ocular hypertension than in those of normotensive rats. The 44.5 kDa protein band was mainly composed of α-enolase, S-arrestin, and ATP synthase subunits α and β, in both the ocular hypertensive and normotensive retinas. Moreover, increasing intraocular pressure was correlated with increasing ATP concentrations in the retinas of rats. Conclusion. Ocular hypertension affected the expression of proteins containing D-β-aspartic acid, including ATP synthase subunits, and up-regulation of ATP in the retinas of rats.

scholarly journals N-Terminomics Strategies for Protease Substrates Profiling

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4699
Author(s):  
Mubashir Mintoo ◽  
Amritangshu Chakravarty ◽  
Ronak Tilvawala
Keyword(s):  
Mass Spectrometry ◽  
Protease Activity ◽  
Viral Infections ◽  
Mass Spectrometry Analysis ◽  
Post Translational Modification ◽  
Spectrometry Analysis ◽  
Physiological Conditions ◽  
Inflammatory Conditions ◽  
Biological Mixtures

Proteases play a central role in various biochemical pathways catalyzing and regulating key biological events. Proteases catalyze an irreversible post-translational modification called proteolysis by hydrolyzing peptide bonds in proteins. Given the destructive potential of proteolysis, protease activity is tightly regulated. Dysregulation of protease activity has been reported in numerous disease conditions, including cancers, neurodegenerative diseases, inflammatory conditions, cardiovascular diseases, and viral infections. The proteolytic profile of a cell, tissue, or organ is governed by protease activation, activity, and substrate specificity. Thus, identifying protease substrates and proteolytic events under physiological conditions can provide crucial information about how the change in protease regulation can alter the cellular proteolytic landscape. In recent years, mass spectrometry-based techniques called N-terminomics have become instrumental in identifying protease substrates from complex biological mixtures. N-terminomics employs the labeling and enrichment of native and neo-N-termini peptides, generated upon proteolysis followed by mass spectrometry analysis allowing protease substrate profiling directly from biological samples. In this review, we provide a brief overview of N-terminomics techniques, focusing on their strengths, weaknesses, limitations, and providing specific examples where they were successfully employed to identify protease substrates in vivo and under physiological conditions. In addition, we explore the current trends in the protease field and the potential for future developments.

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