scholarly journals Structure and Function of the Golgi Complex in Rice Cells (II. Purification and Characterization of Golgi Membrane-Bound Nucleoside Diphosphatase)

1994 ◽  
Vol 106 (1) ◽  
pp. 119-125 ◽  
Author(s):  
T. Mitsui ◽  
M. Honma ◽  
T. Kondo ◽  
N. Hashimoto ◽  
S. Kimura ◽  
...  
Keyword(s):  
Golgi Complex ◽  
Structure And Function ◽  
Golgi Membrane ◽  
Purification And Characterization ◽  
Membrane Bound ◽  
And Function ◽  
Nucleoside Diphosphatase

scholarly journals PV1 Protein from Plasmodium falciparum Exhibits Chaperone-Like Functions and Cooperates with Hsp100s

2020 ◽  
Vol 21 (22) ◽  
pp. 8616
Author(s):  
Kazuaki Hakamada ◽  
Manami Nakamura ◽  
Rio Midorikawa ◽  
Kyosuke Shinohara ◽  
Keiichi Noguchi ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Chaperones ◽  
Structural Unit ◽  
Specific Interaction ◽  
Structure And Function ◽  
Parasite Growth ◽  
Purification And Characterization ◽  
Vacuolar Protein ◽  
And Function

Plasmodium falciparum parasitophorous vacuolar protein 1 (PfPV1), a protein unique to malaria parasites, is localized in the parasitophorous vacuolar (PV) and is essential for parasite growth. Previous studies suggested that PfPV1 cooperates with the Plasmodium translocon of exported proteins (PTEX) complex to export various proteins from the PV. However, the structure and function of PfPV1 have not been determined in detail. In this study, we undertook the expression, purification, and characterization of PfPV1. The tetramer appears to be the structural unit of PfPV1. The activity of PfPV1 appears to be similar to that of molecular chaperones, and it may interact with various proteins. PfPV1 could substitute CtHsp40 in the CtHsp104, CtHsp70, and CtHsp40 protein disaggregation systems. Based on these results, we propose a model in which PfPV1 captures various PV proteins and delivers them to PTEX through a specific interaction with HSP101.

scholarly journals A Rubisco-binding protein is required for normal pyrenoid number and starch sheath morphology inChlamydomonas reinhardtii

2019 ◽  
Vol 116 (37) ◽  
pp. 18445-18454 ◽  
Author(s):  
Alan K. Itakura ◽  
Kher Xing Chan ◽  
Nicky Atkinson ◽  
Leif Pallesen ◽  
Lianyong Wang ◽  
...  
Keyword(s):  
Surface Area ◽  
Structure And Function ◽  
Binding Motif ◽  
Starch Granules ◽  
Wild Type ◽  
Bisphosphate Carboxylase ◽  
Biophysical Mechanism ◽  
Mechanism Function ◽  
And Function

A phase-separated, liquid-like organelle called the pyrenoid mediates CO2fixation in the chloroplasts of nearly all eukaryotic algae. While most algae have 1 pyrenoid per chloroplast, here we describe a mutant in the model algaChlamydomonasthat has on average 10 pyrenoids per chloroplast. Characterization of the mutant leads us to propose a model where multiple pyrenoids are favored by an increase in the surface area of the starch sheath that surrounds and binds to the liquid-like pyrenoid matrix. We find that the mutant’s phenotypes are due to disruption of a gene, which we call StArch Granules Abnormal 1 (SAGA1) because starch sheath granules, or plates, in mutants lacking SAGA1 are more elongated and thinner than those of wild type. SAGA1 contains a starch binding motif, suggesting that it may directly regulate starch sheath morphology. SAGA1 localizes to multiple puncta and streaks in the pyrenoid and physically interacts with the small and large subunits of the carbon-fixing enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), a major component of the liquid-like pyrenoid matrix. Our findings suggest a biophysical mechanism by which starch sheath morphology affects pyrenoid number and CO2-concentrating mechanism function, advancing our understanding of the structure and function of this biogeochemically important organelle. More broadly, we propose that the number of phase-separated organelles can be regulated by imposing constraints on their surface area.

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