# Molecular Mechanisms of Organelle Formation in Bacteria

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA BERKELEY · 2021 · $378,964

## Abstract

Project Abstract
Lipid-bounded organelles are touted as a defining feature of eukaryotes and one which is absent from the
architecturally primitive cells of bacteria. However, numerous bacteria use lipid-bounded organelles to execute
essential, and at times toxic, biochemical reactions in a compartmentalized fashion. My group uses the
magnetosome organelles of magnetotactic bacteria as a model for understanding the mechanistic basis of
organelle formation and function in bacteria. Magnetosomes are lipid-bilayer invaginations of the cell
membrane with a unique protein content, within which nanometer-sized iron-based magnetic crystals are
produced. Individual magnetosomes are arranged into a chain with the help of an actin-like cytoskeleton, thus
allowing magnetotactic bacteria to use geomagnetic fields as a simple guide for low oxygen environments. The
cell biological features of magnetosomes make them ideal for understanding the molecular basis of organelle
biogenesis in bacteria and, perhaps, uncover the evolutionary origins of eukaryotic organelles. The magnetic
and physical properties of magnetosomes make them attractive targets for the development of biomedical
applications including their use as contrast agents for magnetic resonance imaging, as drug delivery vehicles
and as a medium for hyperthermic killing of tumor cells. In addition to magnetosomes, my group has recently
discovered a novel iron-accumulating lipid-bounded organelle named the ferrosome. Ferrosomes are formed
through the action of a small number of genes and are found in diverse bacteria including resident members of
the gut microbiome and opportunistic pathogens. The research program outlined in this proposal will leverage
the expertise and existing knowledge within my group to explore the most critical areas of magnetosome and
ferrosome biology. First, we will focus on the cell biological mechanisms that allow for formation and
subcellular organization of magnetosomes. We will define the minimal components required for the biogenesis
of the magnetosome membrane, uncover the modes and dynamics of protein localization to magnetosomes
and study the biochemical and biophysical characteristics of the actin-like cytoskeleton required for
organization of magnetosomes. Second, we will investigate the mechanisms of iron biomineralization within
magnetosomes. We will uncover the interactions, activity and function of proteins implicated in the nucleation
and growth of magnetic particles and will develop simplified in vitro systems to define the kinetics and chemical
requirements for biomineralization. Finally, we will use this project period to develop ferrosomes into an
alternate and robust model for the study of bacterial organelles. We will determine the mechanisms of
ferrosome membrane biogenesis, protein sorting and iron transport and in parallel define their physiological
function in relevant microorganisms. The combination of these approaches will shed light on the evolution ...

## Key facts

- **NIH application ID:** 10150885
- **Project number:** 5R35GM127114-04
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Arash Komeili
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $378,964
- **Award type:** 5
- **Project period:** 2018-05-01 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10150885

## Citation

> US National Institutes of Health, RePORTER application 10150885, Molecular Mechanisms of Organelle Formation in Bacteria (5R35GM127114-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10150885. Licensed CC0.

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