Mol MicroErhardt lab

Assembly and function of bacterial nanomachines

We study how bacteria regulate, assemble and energise molecular machines: the flagellum, the injectisome, the conjugation machinery and anti-phage defence systems.

ResearchBuild a flagellum

From a single protein to a nanomachine

A single protein measures a few nanometres. Bacterial nanomachines consist of thousands of protein subunits and span the cell envelope.

Our main model is the flagellum. It self-assembles from more than 20,000 subunits of about two dozen proteins. We also study what these machines cost the cell and how pathogens use them during infection. We combine bacterial genetics, biochemistry, fluorescence and super-resolution microscopy, microfluidics and biophysical modelling.

From left to right: protein (CheY), protein complex (FlhD4C2), stator unit, flagellar motor, cell.
The flagellum assembles in the cell envelopeScroll story

Build a flagellum

Scroll through the assembly of the flagellum, from the export gate to the swimming cell, with the structure of each step.

Start Watch the movie

Research topics

Research overview
  1. FlagellaAssembly, protein export and rotation of the bacterial flagellum
  2. Phage defence5:2 rotary motors in motility and anti-phage defence
  3. InjectisomeExpression and substrate targeting of the SPI-1 injectisome
  4. Host and pathogenCosts and benefits of motility during infection
  5. ConjugationDNA transfer by the conjugative type-IV secretion system
  6. Image analysisImage analysis tools for single-cell microscopy

The Zorya defence system contains a relative of the flagellar stator unit

The flagellar stator unit MotA5B2 is a proton-driven rotary motor. A MotA pentamer rotates around a MotB dimer (Santiveri et al. 2020). ZorA5B2, the membrane complex of the Zorya anti-phage defence system, has the same 5:2 architecture and a 70 nm cytoplasmic tail (Hu, Popp et al. 2025).

Our data support a model in which ZorAB is activated when a phage perturbs the cell envelope. The ZorA tail then recruits the effectors ZorC and ZorD, which degrade the phage DNA.

Phage defence research Hu, Popp et al. 2025

MotA5B2 and ZorA5B2 at the same scale (26 s). The function of the ZorA tail is a proposed model.

Molecular movies

All movies
2 min 1 s

Flagellum assembly from real structures

26 s

Unidirectional stator units, bidirectional rotor

28 s

Proposed mechanism of the Zorya defence system

25 s

A minimal filament length for swimming

Recent publications

All publications

News

All news

Lab, software and equipment

Lab page
Lab tour: a walk through the lab in the Rhoda-Erdmann-Haus (81 s).

Junior research groups

People

Two independent junior research groups have emerged from the lab. Both are located at the Institute of Biology.

  • Molecular Infection Microbiology

    Dr. Philipp Popp

    Einstein Independent Researcher group leader since 2026; joined the lab in 2020. The group studies how the anti-phage defence systems of bacteria act together in single cells.

    molinfect.hu-berlin.de

  • Microbial Synthetic Biology

    Dr. Gita Naseri

    Emmy Noether group leader since 2024; joined the lab in 2021. The group develops synthetic biology tools for bacteria, yeast and fungi and applies them in metabolic engineering.

    synbio.hu-berlin.de
Members of the lab at the retreat in 2025
Lab retreat together with the Max Planck Unit for the Science of Pathogens, 2025. Photo: Kathirvel Alagesan.

Team

The lab belongs to the Institute of Biology of Humboldt-Universität zu Berlin and is located on Campus Nord in Berlin-Mitte. Marc Erhardt is also a Max Planck Fellow and leads a second lab, the Erhardt Fellow Lab, at the Max Planck Unit for the Science of Pathogens.

Lab members and alumni

Open positions

We accept applications from PhD students and postdocs, and from students who look for a Bachelor’s or Master’s thesis project.

Positions and theses