Show Notes
Berazategui MA et al., PNAS - ESBX (Tb927.3.1660) links RNA Pol I localization at the ESB to activation of the active BES and repression of inactive BESs in Trypanosoma brucei, supporting monoallelic VSG expression.
Study Highlights:
Using ESB1-guided proximity-dependent biotinylation proteomics, endogenous tagging and high-resolution fluorescence microscopy, RNAi knockdown, RNA-seq, and inducible overexpression in bloodstream-form Trypanosoma brucei, the authors identify Tb927.3.1660 (ESBX) as an ESB-specific protein. ESBX localizes adjacent to Pol I (RPA2) and ESB1 within the ESB with measured center separations of ~68–175 nm and contains predicted SUMO-interacting and BRCT domains. ESBX depletion causes loss of the extranucleolar Pol I ESB focus, reduced processive transcription from the active BES with larger decreases distal to the promoter, and derepression of inactive BESs with low-processivity transcripts, whereas ESBX overexpression weakly activates inactive BESs with processive transcription without forming extra ESBs. Together the data indicate ESBX integrates activation of the active BES with repression of inactive BESs, a mechanism that supports monoallelic VSG expression.
Conclusion:
Tb927.3.1660/ESBX is an ESB component required to integrate activation of the active BES with repression of inactive BESs, thereby supporting monoallelic VSG expression in bloodstream-form Trypanosoma brucei.
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Reference:
Berazategui MA, Wheeler RJ, Tiengwe C, Lansink LIM, Rudenko G, Sunter JD, Goodwin I, Gull K, Faria JRC, et al. A factor integrating transcription and repression of surface antigen genes in African trypanosomes. Proc. Natl. Acad. Sci. U.S.A. 2026.123:e2531377123. https://doi.org/10.1073/pnas.2531377123
License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) - https://creativecommons.org/licenses/by/4.0/
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