# Identifying Remote Regulators of Complex I Biogenesis in Drosophila

> **NIH NIH R35** · COLUMBIA UNIVERSITY HEALTH SCIENCES · 2020 · $400,000

## Abstract

PROJECT SUMMARY
Human Mitochondrial Complex I (CI) is composed of 44 distinct subunits that are assembled together
with eight Fe-S clusters and a single flavin mononucleotide, to form a functioning enzyme. Ancillary
proteins referred to as assembly factors assist with the assembly process; and a dozen or so bona fide CI
assembly factors (CIAFs) have been characterized. However, about half of CI disorders cannot be traced
to mutations in any of the 44 CI subunits or known assembly factors, which suggests that additional
regulators of CI biogenesis remain to be characterized. Some regulators of CI assembly may not directly
interact with any of the 44 CI subunits, but rather interact with CIAFs to regulate CI assembly indirectly.
For instance, they may regulate the stability, subcellular localization, degree of post-translational
modification, extent of activation, etc. of a CIAF. We refer to this class of regulators as remote regulators
(RRs) of CI assembly. We hypothesize that at least some CI disorders may be attributed to mutations in
RRs, many of which have not yet been discovered. The ideal model system for discovering RRs of CI
assembly will have to satisfy at least 4 criteria: (i) the mechanism of CI assembly should closely mimic
that of the human enzyme, (ii) it should be highly enriched with mitochondria to enable the examination
of the effects of 1000s of candidate genes on CI assembly rather easily, (iii) the genetic tool kit in such an
organism should be significantly advanced to the point where the effects of 1000s of candidate genes on
CI assembly can rapidly be tested, and finally (iv) it should be possible to analyze CI assembly in vivo
where it is subject to both developmental and environmental signals, and not prone to cell culture
artifacts. None of the current model systems for studying CI assembly (in Neurospora crassa and various
mammalian cell lines) satisfy all 4 criteria. To facilitate the discovery of RRs of CI assembly, we are
using the mitochondria-enriched flight muscles in Drosophila as a novel system to study CI assembly as it
satisfies all four criteria. We find that CI biogenesis in Drosophila skeletal muscles proceeds via the
formation of ~315-, ~370-, ~550-, and ~815 kDa CI assembly intermediates as has been described in
mammalian systems; and Drosophila CI has a comparable number of subunits as the human enzyme.
Importantly, mutations in Drosophila orthologs of CIAFs described in humans, also impair CI assembly
in Drosophila, further showing that the mechanism of CI assembly is conserved between humans and
Drosophila. Here, we propose to use a genetic and proteomic approach to identify novel RRs of CI
assembly in this system; and test our candidate regulators in both Drosophila and human cells. The ease
of isolating copious amounts of mitochondria from flight muscles, extensive arsenal of tools for genetic
analyses, relatively short generation time, and limited gene redundancy in Drosophila are assets that
should...

## Key facts

- **NIH application ID:** 9978888
- **Project number:** 5R35GM124717-04
- **Recipient organization:** COLUMBIA UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** Edward Owusu-Ansah
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $400,000
- **Award type:** 5
- **Project period:** 2017-08-08 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9978888

## Citation

> US National Institutes of Health, RePORTER application 9978888, Identifying Remote Regulators of Complex I Biogenesis in Drosophila (5R35GM124717-04). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/9978888. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*