# The mechanism of apo-target recognition in cytsolic iron sulfur cluster biosynthesis

> **NIH NIH R01** · BOSTON UNIVERSITY (CHARLES RIVER CAMPUS) · 2020 · $317,625

## Abstract

Project Summary/Abstract
The cytosolic iron sulfur (FeS) cluster assembly (CIA) pathway is essential since it supplies FeS clusters to
enzymes which are essential for DNA replication and repair, transcription, and translation. Despite CIA's
unquestionable importance for cell growth and division, we understand little about its mechanism. In particular,
there is a dearth of information regarding how the >20 FeS-enzyme “targets” differing in their sequence,
structure and function are all identified as CIA substrates so that their cofactors can be inserted in the final step
of the pathway. Recent work has pinpointed a multiprotein complex, termed the CIA targeting complex (CTC),
as being essential for this apo-target recognition step. The CTC subunits, called Met18, Cia1 and Cia2 in
yeast, are highly conserved across the eukaryotic kingdom and their depletion results in a defect in FeS
cofactor maturation in cytosolic and nuclear, but not mitochondrial, enzymes. However, progress to understand
the final step of CIA has been slow due, in part, to the inability to access a reconstituted in vitro system for
mechanistic analysis. We have recently overcome this barrier and are now poised to begin elucidating the
mechanism by which apo-targets are identified. The remarkable ability of the CTC to flexibly yet specifically
recognize the diverse pool of CIA targets is likely accomplished by Met18, Cia1 and Cia2 forming multiple
distinct complexes, each responsible for recognition of a distinct subset of targets, by individual targets or
subsets of targets sharing a common targeting motif sufficient for association with the CTC or by a combination
of these two mechanisms. To reveal the molecular details underlying apo-target identification, we will 1)
identify residues critical for formation of the targeting complex and evaluate how their mutation affects CIA
function in vivo; 2) complete a comprehensive screen to identify functional residues of CTC subunits and
pinpoint which are essential for target-binding in vitro and in vivo; and 3) elucidate the targeting motif exploited
by the cytosolic FeS protein Leu1 and the nuclear FeS protein Rad3 for their association with the targeting
complex. Successful completion of these aims is expected to provide fundamental knowledge about the
structure of the targeting complex and the role(s) of its individual subunits, reveal the cryptic code driving CIA
target recognition, and yield new information about how different targets or subsets of targets are identified by
the CIA system. Since target recognition is not well understood for any cluster biogenesis pathway, this project
is expected to shed light on this long-standing black box in the cluster biogenesis field. Finally, since defects
CIA function result in sensitivity to DNA damaging agents, chromosomal instabilities, elongated telomeres and
other genotoxic phenotypes, elucidation of the fundamental mechanism underlying CIA substrate recognition is
expected to provi...

## Key facts

- **NIH application ID:** 9975865
- **Project number:** 5R01GM121673-03
- **Recipient organization:** BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
- **Principal Investigator:** DEBORAH L PERLSTEIN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $317,625
- **Award type:** 5
- **Project period:** 2018-09-05 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9975865

## Citation

> US National Institutes of Health, RePORTER application 9975865, The mechanism of apo-target recognition in cytsolic iron sulfur cluster biosynthesis (5R01GM121673-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9975865. Licensed CC0.

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