Rebecca J. Burge , Katie H. Jameson , Vincent Geoghegan , Adam A. Dowle , Jeremy C. Mottram , Anthony J. Wilkinson
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引用次数: 0
Abstract
In eukaryotic cells, molecular fate and cellular responses are shaped by multicomponent enzyme systems which reversibly attach ubiquitin and ubiquitin-like modifiers to target proteins. The extent of the ubiquitin proteasome system in Leishmania mexicana and its importance for parasite survival has recently been established through deletion mutagenesis and life-cycle phenotyping studies. The ubiquitin conjugating E2 enzyme UBC2, and the E2 enzyme variant UEV1, with which it forms a stable complex in vitro, were shown to be essential for the differentiation of promastigote parasites to the infectious amastigote form. To investigate further, we used immunoprecipitation of Myc-UBC2 or Myc-UEV1 to identify interacting proteins in L. mexicana promastigotes. The interactome of UBC2 comprises multiple ubiquitin-proteasome components including UEV1 and four RING E3 ligases, as well as potential substrates predicted to have roles in carbohydrate metabolism and intracellular trafficking. The smaller UEV1 interactome comprises six proteins, including UBC2 and shared components of the UBC2 interactome consistent with the presence of intracellular UBC2-UEV1 complexes. Recombinant RING1, RING2 and RING4 E3 ligases were shown to support ubiquitin transfer reactions involving the E1, UBA1a, and UBC2 to available substrate proteins or to unanchored ubiquitin chains. These studies define additional components of a UBC2-dependent ubiquitination pathway shown previously to be essential for promastigote to amastigote differentiation.
期刊介绍:
The journal provides a medium for rapid publication of investigations of the molecular biology and biochemistry of parasitic protozoa and helminths and their interactions with both the definitive and intermediate host. The main subject areas covered are:
• the structure, biosynthesis, degradation, properties and function of DNA, RNA, proteins, lipids, carbohydrates and small molecular-weight substances
• intermediary metabolism and bioenergetics
• drug target characterization and the mode of action of antiparasitic drugs
• molecular and biochemical aspects of membrane structure and function
• host-parasite relationships that focus on the parasite, particularly as related to specific parasite molecules.
• analysis of genes and genome structure, function and expression
• analysis of variation in parasite populations relevant to genetic exchange, pathogenesis, drug and vaccine target characterization, and drug resistance.
• parasite protein trafficking, organelle biogenesis, and cellular structure especially with reference to the roles of specific molecules
• parasite programmed cell death, development, and cell division at the molecular level.