scholarly journals Insight into the Binding and Hydrolytic Preferences of hNudt16 Based on Nucleotide Diphosphate Substrates

2021 ◽  
Vol 22 (20) ◽  
pp. 10929
Author(s):  
Magdalena Chrabąszczewska ◽  
Maria Winiewska-Szajewska ◽  
Natalia Ostrowska ◽  
Elżbieta Bojarska ◽  
Janusz Stępiński ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Substrate Specificity ◽  
Ligand Binding ◽  
Regulatory Role ◽  
Stacking Interactions ◽  
Binding Modes ◽  
Biological Functions ◽  
Insight Into ◽  
Potential Regulatory Role

Nudt16 is a member of the NUDIX family of hydrolases that show specificity towards substrates consisting of a nucleoside diphosphate linked to another moiety X. Several substrates for hNudt16 and various possible biological functions have been reported. However, some of these reports contradict each other and studies comparing the substrate specificity of the hNudt16 protein are limited. Therefore, we quantitatively compared the affinity of hNudt16 towards a set of previously published substrates, as well as identified novel potential substrates. Here, we show that hNudt16 has the highest affinity towards IDP and GppG, with Kd below 100 nM. Other tested ligands exhibited a weaker affinity of several orders of magnitude. Among the investigated compounds, only IDP, GppG, m7GppG, AppA, dpCoA, and NADH were hydrolyzed by hNudt16 with a strong substrate preference for inosine or guanosine containing compounds. A new identified substrate for hNudt16, GppG, which binds the enzyme with an affinity comparable to that of IDP, suggests another potential regulatory role of this protein. Molecular docking of hNudt16-ligand binding inside the hNudt16 pocket revealed two binding modes for representative substrates. Nucleobase stabilization by Π stacking interactions with His24 has been associated with strong binding of hNudt16 substrates.

scholarly journals Potential Regulatory Role of Competitive Encounter Complexes in Paralogous Phosphotransferase Systems

2019 ◽  
Vol 431 (12) ◽  
pp. 2331-2342 ◽  
Author(s):  
Madeleine Strickland ◽  
Seyit Kale ◽  
Marie-Paule Strub ◽  
Charles D. Schwieters ◽  
Jian Liu ◽  
...  
Keyword(s):  
Regulatory Role ◽  
Potential Regulatory Role

scholarly journals In vivo evidence for a regulatory role of phosphorylation ofArabidopsisRubisco activase at the Thr78 site

2019 ◽  
Vol 116 (37) ◽  
pp. 18723-18731 ◽  
Author(s):  
Sang Yeol Kim ◽  
Christopher M. Harvey ◽  
Jonas Giese ◽  
Ines Lassowskat ◽  
Vijayata Singh ◽  
...  
Keyword(s):  
Redox Regulation ◽  
Rubisco Activase ◽  
Regulatory Role ◽  
Wild Type ◽  
Low Light ◽  
Induction Kinetics ◽  
Potential Regulatory Role ◽  
Wild Type Control

ArabidopsisRubisco activase (Rca) is phosphorylated at threonine-78 (Thr78) in low light and in the dark, suggesting a potential regulatory role in photosynthesis, but this has not been directly tested. To do so, we transformed anrca-knockdown mutant largely lacking redox regulation with wild-type Rca-β or Rca-β with Thr78-to-Ala (T78A) or Thr78-to-Ser (T78S) site–directed mutations. Interestingly, the T78S mutant was hyperphosphorylated at the Ser78 site relative to Thr78 of the Rca-β wild-type control, as evidenced by immunoblotting with custom antibodies and quantitative mass spectrometry. Moreover, plants expressing the T78S mutation had reduced photosynthesis and quantum efficiency of photosystem II (ϕPSII) and reduced growth relative to control plants expressing wild-type Rca-β under all conditions tested. Gene expression was also altered in a manner consistent with reduced growth. In contrast, plants expressing Rca-β with the phospho-null T78A mutation had faster photosynthetic induction kinetics and increased ϕPSIIrelative to Rca-β controls. While expression of the wild-type Rca-β or the T78A mutant fully rescued the slow-growth phenotype of therca-knockdown mutant grown in a square-wave light regime, the T78A mutants grew faster than the Rca-β control plants at low light (30 µmol photons m−2s−1) and in a fluctuating low-light/high-light environment. Collectively, these results suggest that phosphorylation of Thr78 (or Ser78 in the T78S mutant) plays a negative regulatory role in vivo and provides an explanation for the absence of Ser at position 78 in terrestrial plant species.

scholarly journals Angiostatic cues from the matrix: Endothelial cell autophagy meets hyaluronan biology

2020 ◽  
Vol 295 (49) ◽  
pp. 16797-16812
Author(s):  
Carolyn G. Chen ◽  
Renato V. Iozzo
Keyword(s):  
Molecular Mechanisms ◽  
Biological Functions ◽  
Post Translational Modifications ◽  
Binding Partner ◽  
Master Regulators ◽  
The Matrix ◽  
Vascular Endothelia ◽  
Insight Into ◽  
Review Current

The extracellular matrix encompasses a reservoir of bioactive macromolecules that modulates a cornucopia of biological functions. A prominent body of work posits matrix constituents as master regulators of autophagy and angiogenesis and provides molecular insight into how these two processes are coordinated. Here, we review current understanding of the molecular mechanisms underlying hyaluronan and HAS2 regulation and the role of soluble proteoglycan in affecting autophagy and angiogenesis. Specifically, we assess the role of proteoglycan-evoked autophagy in regulating angiogenesis via the HAS2-hyaluronan axis and ATG9A, a novel HAS2 binding partner. We discuss extracellular hyaluronan biology and the post-transcriptional and post-translational modifications that regulate its main synthesizer, HAS2. We highlight the emerging group of proteoglycans that utilize outside-in signaling to modulate autophagy and angiogenesis in cancer microenvironments and thoroughly review the most up-to-date understanding of endorepellin signaling in vascular endothelia, providing insight into the temporal complexities involved.

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