Department of Cell and Molecular Biology

Research projects

Evolution of host-adapted bacteria

The research in Siv Andersson´s group aims at understanding how intracellular bacteria and organelles evolve. A long-term goal is to design novel intracellular bacterial genomes with beneficial functions using synthetic biology. To achieve this goal we need a basic understanding of the interplay between bacteria and hosts, and why organelles and mutualistic bacteria need a distinct genome. Below are a few examples of ongoing projects.

Why do some organisms need bacteria?

Many host-adapted bacterial populations produce nutrients that the host cannot get from its diet. Others produce antimicrobials to defend the host against pathogens and other invading microbes. The secreted compounds benefit the whole bacterial population and/or the host, but are costly to make for the individual bacterial cell. Hence there is a risk that cheaters arise that benefit from the secreted compounds without contributing to their production. In this project, we use bacteria adapted to mammals and insects as model systems to study how the production of the public good is organized and how cheaters are avoided in the bacterial population.

Why do some cells need internal compartments?

Eukaryotic cells contain several membrane-bound compartments, such as for example mitochondria. Bacterial cells do not normally contain internal membranes. But there are exceptions. To understand why and how complex cellular architectures arise we study bacterial cells that contain a network of internal membranes and connected vesicles. In this project, we use comparative, functional and ecological genomics to learn more about cellular compartmentalization.

Why do some compartments need a genome?

We have recently published results that support the hypothesis that mitochondria need a genome to avoid that the encoded proteins are transported to the Endoplasmatic Reticulum. Transporting proteins between compartments inside the cell requires a multitude of signals to ensure that each protein reaches its final destination. In this project, we use bioinformatics and experimental methods to learn more about why mitochondria need a distinct genome.

This work is supported by the Swedish Research Council (VR) and the Knut and Alice Wallenberg Foundation (KAW). In addition, we participate in several collaborative projects: Uppsala Center for Evolutionary Genomics (supported by VR), the Human Microbiome in Health and Disease (supported by KAW) and Inland Water Ecosystems in the Global Carbon CycleTowards a Mechanistic Understanding (supported by KAW).