Disputation: Daniel Hatlem

PhD candidate Daniel Hatlem at the Department of Biosciences will be defending the thesis "Probing the role of lipopolysaccharides in Gram-negative protein secretion and biogenesis" for the degree of PhD.

Profile picture of Daniel Hatlem

Daniel Hatlem

The trial lecture is: "LPS receptors and sensing in nature".

Time and place: April.25, 2022 10:15 AM, Zoom

The events will be live streamed using Zoom. The host of the session will moderate the technicalities while the chair of the defence will moderate the events.

Ex auditorio questions: The chair of the defence will invite the audience to ask ex auditorio questions either written or oral. This can be requested by clicking "Participants" followed by clicking "Raise hand". 

The events opens for participation just before they start, and closes for new participants approximately 15 minutes after it has begun.

Main research findings

Antimicrobial resistance is becoming a global health-threat, prompting the development of new methods to combat bacterial infections. In order to develop such methods, we need a greater understanding of the underlying processes of the bacterial life cycle and infection. In this thesis, I focus on the surface envelope of Gram-negative bacteria, termed the outer membrane (OM). The OM is asymmetric, composed of an inner phospholipid layer and outer layer composed of glycolipids termed lipopolysaccharides (LPS). In order to maintain essential cellular functions and interact with its host during infection, the bacterium must secrete proteins across the OM to the surface. In order to achieve this, bacteria have developed a range of general secretion systems, responsible for bringing the proteins to the surface.

The aim of this thesis was to study the biogenesis and secretion of the Type 5c secretion system, and the role of LPS in this process. Here it was demonstrated that T5cSS secretion is initiated by the formation of a hairpin loop, in a similar fashion as other members of the Type 5 secretion system family. Further investigation of the role LPS in secretion led to a serendipitous discovery of a small coiled-coil peptide that binds LPS with high affinity. Upon realizing the potential uses for the peptide in biotechnology, the discovery sidetracked our plans, to rather characterize this interaction. Additionally, the heat-labile enterotoxin was studied with the aim of elucidating how it interacts with LPS during secretion and toxin delivery.

Adjudication committee

Professor Håvard Jenssen, Roskilde University

Professor Christoph Mayer, University of Tübingen

Professor emeritus Reidun Kavli Sirevåg, University of Oslo

Chair of defence

Professor Rein Aasland, University of Oslo


Professor Dirk Linke, University of Oslo

Professor Ute Krengel, University of Oslo

Published Apr. 22, 2022 7:13 AM - Last modified May 9, 2022 11:10 AM