Proteomic Analysis of Human Angiogenin Interactions Reveals Cytoplasmic PCNA as a Putative Binding Partner

Human Angiogenin (hAng) is a member of the ribonuclease A superfamily and a potent inducer of neovascularization. Protein interactions of hAng in the nucleus and cytoplasm of the human umbilical vein cell line EA.hy926 have been investigated by mass spectroscopy. Data are available via ProteomeXchange with identifiers PXD006583 and PXD006584. The first gel-free analysis of hAng immunoprecipitates revealed many statistically significant potential hAng-interacting proteins involved in crucial biological pathways. Surprisingly, proliferating cell nuclear antigen (PCNA), was found to be immunoprecipitated with hAng only in the cytoplasm. The hAng–PCNA interaction and colocalization in the specific cellular compartment was validated with immunoprecipitation, immunoblotting, and immunocytochemistry. The results revealed that PCNA is predominantly localized in the cytoplasm, while hAng is distributed both in the nucleus and in the cytoplasm. hAng and PCNA colocalize in the cytoplasm, suggesting that they may interact in this compartment

AtHESPERIN: a novel regulator of circadian rhythms with poly(A)-degrading activity in plants

<p>We report the identification and characterization of a novel gene, <i>AtHesperin</i> (<i>AtHESP</i>) that codes for a deadenylase in <i>Arabidopsis thaliana</i>. The gene is under circadian clock-gene regulation and has similarity to the mammalian <i>Nocturnin</i>. AtHESP can efficiently degrade poly(A) substrates exhibiting allosteric kinetics. Size exclusion chromatography and native electrophoresis coupled with kinetic analysis support that the native enzyme is oligomeric with at least 3 binding sites. Knockdown and overexpression of <i>AtHESP</i> in plant lines affects the expression and rhythmicity of the clock core oscillator genes <i>TOC1</i> and <i>CCA1</i>. This study demonstrates an evolutionary conserved poly(A)-degrading activity in plants and suggests deadenylation as a mechanism involved in the regulation of the circadian clock. A role of <i>AtHESP</i> in stress response in plants is also depicted.</p

Nanomolar Inhibitors of Glycogen Phosphorylase Based on β‑d‑Glucosaminyl Heterocycles: A Combined Synthetic, Enzyme Kinetic, and Protein Crystallography Study

Aryl substituted 1-(β-d-glucosaminyl)-1,2,3-triazoles as well as <i>C</i>-β-d-glucosaminyl 1,2,4-triazoles and imidazoles were synthesized and tested as inhibitors against muscle and liver isoforms of glycogen phosphorylase (GP). While the <i>N</i>-β-d-glucosaminyl 1,2,3-triazoles showed weak or no inhibition, the <i>C</i>-β-d-glucosaminyl derivatives had potent activity, and the best inhibitor was the 2-(β-d-glucosaminyl)-4­(5)-(2-naphthyl)-imidazole with a <i>K</i>_i value of 143 nM against human liver GPa. An X-ray crystallography study of the rabbit muscle GPb inhibitor complexes revealed structural features of the strong binding and offered an explanation for the differences in inhibitory potency between glucosyl and glucosaminyl derivatives and also for the differences between imidazole and 1,2,4-triazole analogues