11/08/2022
By Danielle Fretwell

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a master’s thesis defense by Samuel Fredericksen on “Inducing Secretion of Recombinantly Expressed Proteins in E. coli via FlgM and the Type-III Secretion System.” 

Candidate Name: Samuel Fredericksen
Defense Date: Monday, Nov. 21, 2022
Time: 2 to 3 p.m.
Location: Olney Hall 518. Those interested in attending virtually should contact Samuel_Fredericksen@student.uml.edu for a link.

Committee: Advisor: Prof. Dongming Xie, Chemical Engineering, University of Massachusetts Lowell

Committee Members:

  • Prof. Matthew Gage, Chemistry, University of Massachusetts Lowell
  • Prof. Eric Maase Chemical Engineering, University of Massachusetts Lowell

Brief Abstract:
Production and purification of recombinant proteins can be an arduous and time-consuming task, but one that is critical for many biochemistry labs. Low yields, inclusion body formation, and aggregation are just a few of the roadblocks that can hinder obtaining high-quality proteins for experiments. Many of these issues arise from the myriad of host proteins generated by E. coli, so expression systems that secrete recombinantly expressed protein can alleviate many roadblocks. Despite the years of research that has been invested understanding secretion systems, a reliable system to secrete recombinant protein in bacteria remains elusive.

The FlgM protein is a naturally secreted peptide that is involved in regulating the formation of the type-III secretion system (T3SS). Preliminary experiments have shown that by fusing FlgM to proteins of interest, it is possible to induce secretion of the entire construct. This work focuses on elucidating the mechanism of secretion and determining methods by which to maximize the titer of secreted protein. These goals were achieved by firstly generating and expressing constructs that contained truncated versions of FlgM, which showed that multiple regions of the peptide are recognized and utilized by the type-III secretion pathway. Secondly, the general mode of secretion was observed, and the efficacy of the process was found to depend strongly on temperature and time. Finally, a DoE (design of experiments) study was designed to determine the specific interactions of process variables on protein titer.

All interested students and faculty members are invited to attend.