In Memoriam

We use a variety of approaches to investigate several of the fundamental and conserved processes used by bacteria for propagation and growth, adaptation to stresses, and acquisition of new genes and traits via horizontal gene transfer. Our long term goals are to understand many of the molecular mechanisms and regulation underlying basic cellular processes in bacteria. Our organism of choice for these studies is usually the Gram positive bacterium Bacillus subtilis. Our current efforts are focused in two important areas of biology: 1) The control of horizontal gene transfer, specifically the lifecycle, function, and control of integrative and conjugative elements (ICEs). These elements are widespread in bacteria and contribute greatly to the spread of antibiotic resistances between organisms. 2) Regulation of the initiation of DNA replication and the connections between replication and gene expression, with particular focus on the conserved replication initiator and transcription factor DnaA. This work is directly related to mechanisms controlling bacterial growth, survival, and stress responses.

The Kaiser lab studied protein folding and intracellular trafficking in the yeast S. cerevisiae. Their work focused on the protein folding in the endoplasmic reticulum (ER), quality control mechanisms in the ER, and membrane protein sorting in Golgi compartments. They combined genetic, biochemical, and cell biological methods to gain an understanding of the molecular mechanisms underlying each of these processes. Chris Kaiser is no longer accepting students.

Faculty Bio: Daniel Lew joined the Department of Biology at MIT as a Professor in the Spring of 2023. Professor Lew completed a PhD in Molecular Biology from the Rockefeller University in 1990, and then did postdoctoral work at the Scripps Research Institute where he investigated the cell cycle control in the model yeast Saccharomyces cerevisiae. His research focuses on the study of cell polarity and the spatial decoding of chemical signals by cells, which are critical for many biological phenomena.

Research Summary: We study questions in fundamental cell biology, using fungal models and a mix of experimental and computational approaches. Fungi and animals share conserved molecular strategies to perform many core cell functions, so the tractable yeast Saccharomyces cerevisiae provides a superb model system to gain in-depth understanding that can be translated into computational models. We also study an emerging non-model fungus, Aureobasidium pullulans, that is an ubiquitous poly-extremophile with unconventional growth modes that raise novel questions in cell biology.

Some questions of interest:

• How do cells regulate cell polarity to achieve different morphologies?
• How do cells orient cell polarity in response to extracellular signals?
• How do cells distribute their contents, particularly in complex geometries?
• How do fungi growing under stringent turgor pressure expand their cell walls without lysing?
• How do cell-cell contacts between cell walls communicate mechanical information to the cell?