Disputation: Thomas Trunk
Doctoral candidate Thomas Trunk at the Department of Biosciences will be defending the thesis "Characterization and comparative analyses of type Vd-secreted phospholipases expressed in pathogenic bacteria" for the degree of Philosophiae Doctor.
The University of Oslo is partly closed at the moment, due to the Corona Pandemic. The disputation will therefore be live streamed using Zoom. The host of the session will moderate the technicalities while the chair of the defence will moderate the disputation.
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 meeting opens for participation just before 13.15 PM, and closes for new participants approximately 15 minutes after the defense has begun.
Protein secretion from Gram positive bacteria and how it differs from the machineris found in Gram negatives.
Main research findings
Characterization and comparative analyses of type Vd-secreted phospholipases expressed in pathogenic bacteria
Autotransporters, or type 5 secretion systems (T5SS), are widespread surface proteins of Gram-negative bacteria often associated with virulence. Three novel T5dSSs expressed in the fish pathogen Aeromonas hydrophila, the phytopathogen Ralstonia solanacearum and the human pathogen Burkholderia pseudomallei are presented in this thesis alongside the complementation of the enzymatic characterization of the T5dSS phospholipases from Pseudomonas aeruginosa and Fusobacterium nucleatum, already known to literature. Detailed information on the phospholipases’ relative enzyme activities, substrate specificities as well as the role of quaternary structure for enzyme activity and stability are shown. Furthermore, a low resolution (6 Å) structure of the T5dSS phospholipase from the fish pathogen Aeromonas hydrophila is presented, showing high structural similarity with the T5dSS present in Pseudomonas aeruginosa.
Additionally, the results in the thesis show the role of the periplasmic chaperone SurA on integration of the T5dSS of Pseudomonas aeruginosa into the outer membrane as well as the chaperones effect on membrane integrity and outer membrane composition. With an increased accessibility as well as sensitivity to antibiotics resulting from a conditional deletion of SurA, the chaperone might qualify as potential novel antimicrobial target.