Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P62988 (Ubiquitin)
 4,326 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The plant hormone indole-3 acetic acid (IAA or auxin) controls many aspects of plant development, including the production of lateral roots. Ubiquitin-mediated proteolysis has a central role in this process. The genes AXR1 and TIR1 aid the assembly of an active SCF (Skp1/Cullin/F-box) complex that probably promotes degradation of the AUX/IAA transcriptional repressors in response to auxin. The transcription activator NAC1, a member of the NAM/CUC family of transcription factors, functions downstream of TIR1 to transduce the auxin signal for lateral root development. Here we show that SINAT5, an Arabidopsis homologue of the RING-finger Drosophila protein SINA, has ubiquitin protein ligase activity and can ubiquitinate NAC1. This activity is abolished by mutations in the RING motif of SINAT5. Overexpressing SINAT5 produces fewer lateral roots, whereas overexpression of a dominant-negative Cys49 --> Ser mutant of SINAT5 develops more lateral roots. These lateral root phenotypes correlate with the expression of NAC1 observed in vivo. Low expression of NAC1 in roots can be increased by treatment with a proteasome inhibitor, which indicates that SINAT5 targets NAC1 for ubiquitin-mediated proteolysis to downregulate auxin signals in plant cells.
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PMID:SINAT5 promotes ubiquitin-related degradation of NAC1 to attenuate auxin signals. 1222 65

Ubiquitination is a prevalent protein modification catalyzed by E1, E2, and E3 enzymes that activate, conjugate, and ligate, respectively, the ubiquitin protein to substrate protein. In order to establish a mutualistic or parasitic relationship with their eukaryotic hosts, many microorganisms hijack different aspects of the ubiquitination machinery using bacterial proteins that function as E3 ligases or as enzymes that modify E2s or ubiquitin. Recently, the SidE family of effector proteins (SidEs) from the intracellular bacterial pathogen Legionella pneumophila was found to catalyze ubiquitination by a mechanism unrelated to the classical three-enzyme cascade. Instead of utilizing ATP, SidEs-catalyzed ubiquitination reactions are energized by nicotinamide adenine dinucleotide (NAD). Ubiquitin is first activated by ADP-ribosylation at residue Arg42 to form ADP-ribosylated ubiquitin (ADPR-Ub). ADPR-Ub is then cleaved by an activity conferred by a phosphodiesterase (PDE)-related domain also embedded in the SidE family proteins. ADPR-Ub cleavage is coupled to covalent attachment of phosphoribosylated ubiquitin to serine residues of target proteins and the release of AMP. Furthermore, SidE-induced ubiquitination can be reversed by SidJ, another virulence factor from L. pneumophila. Here, we describe the experimental details for SdeA-induced ubiquitination of the small GTPase Rab33b and its reversal by SidJ.
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PMID:Methods to study phosphoribosylated ubiquitin ligation and removal. 3085 50