Flagellated kinetoplastid protozoans inflict public health hazards and economic burden predominately on marginalized populations in the developing world. The agents of African human and animal trypanosomiasis, Trypanosoma brucei sp., cause some of the most-studied, but least manageable and curable parasitic infections. Failing vector control, lack of vaccines and toxic therapeutics place the onus on identification, molecular understanding and validation of new drug targets. From the fundamental science perspective, these early branching Excavata represent valuable models of mitochondrial RNA biology, antigenic variation, host-pathogen interaction, post-transcriptional regulation, and other processes. Major findings in the previous funding period position a family of RNA binding pentatricopeptide repeat (PPR, 35 amino acids) proteins as the central conduit controlling mitochondrial gene expression. The unique ability of helix-turn-helix repeats to assemble into superhelical arrays recognizing extended and compositionally diverse RNA sequences enables the essential roles of more than 40 PPRs. Often including trypanosome-specific domains, these RNA ?sequence readers? commit otherwise non-specific modification enzymes to their substrates, or block RNA degradation and extension. This project will elucidate the mechanisms by which nuclear-encoded PPRs govern mitochondrial mRNA biogenesis and translation via recruiting enzymatic complexes and ribosomes to transcripts at defined processing stages. We establish three priority areas focusing on PPRs that enable mRNA 5? end modification, 3? adenylation/uridylation, and translation. Building on our recent discoveries of gene-specific transcription initiation and exonucleolytic pre-mRNA processing, we identified PPR factors acting as ?protein cap,? ?editing sensor,? poly(A) binding protein, and potential translational activators. Our goal is to dissect the molecular machinery integrating these functions and to decipher principles of RNA recognition by repeat-containing proteins. By elucidating their RNA binding sites, structures, interactions, and outcomes of genetic alteration and protein engineering, this program builds on our momentum in a significant field and expands the knowledge of critical pathogen-specific processes.

Public Health Relevance

The goal is to understand the mechanisms by which nuclear-encoded RNA binding pentatricopeptide repeat (PPR, 35 amino acids) proteins orchestrate mitochondrial mRNA biogenesis and translation in Trypanosoma brucei. Because PPR-mediated elements of these processes are unique to a parasite responsible for devastating diseases, the proposed studies will expand the fundamental knowledge of essential molecular mechanisms in a medically and economically significant pathogen.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI113157-07
Application #
10113510
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Joy, Deirdre A
Project Start
2015-01-05
Project End
2025-01-31
Budget Start
2021-02-01
Budget End
2022-01-31
Support Year
7
Fiscal Year
2021
Total Cost
Indirect Cost
Name
Boston University
Department
Dentistry
Type
Schools of Dentistry/Oral Hygn
DUNS #
604483045
City
Boston
State
MA
Country
United States
Zip Code
02118
Sement, Fran├žois M; Suematsu, Takuma; Zhang, Liye et al. (2018) Transcription initiation defines kinetoplast RNA boundaries. Proc Natl Acad Sci U S A 115:E10323-E10332
Zhang, Liye; Sement, Francois M; Suematsu, Takuma et al. (2017) PPR polyadenylation factor defines mitochondrial mRNA identity and stability in trypanosomes. EMBO J 36:2435-2454
Aphasizheva, Inna; Aphasizhev, Ruslan (2016) U-Insertion/Deletion mRNA-Editing Holoenzyme: Definition in Sight. Trends Parasitol 32:144-156
Aphasizheva, Inna; Zhang, Liye; Aphasizhev, Ruslan (2016) Investigating RNA editing factors from trypanosome mitochondria. Methods 107:23-33
Aphasizheva, Inna; Maslov, Dmitri A; Qian, Yu et al. (2016) Ribosome-associated pentatricopeptide repeat proteins function as translational activators in mitochondria of trypanosomes. Mol Microbiol 99:1043-58