The Significance of the N-terminal Region of TolQ in Maintaining Tol-associated Energy-dependent Functions and Cell Division in Escherichia coli
Abstract (Summary)The composition of the Tol protein system is conserved throughout the Gram negative bacteria and functions to couple cytoplasmic membrane-derived energy to outer membrane targets in K-12 strains of Escherichia coli. Outer membrane integrity is reliant upon the Tol system and the Tol proteins are parasitized by a number of bacteriophage and bacterial toxins termed group A colicins. The broad host range bacteriophage P1 utilizes the Tol system of E. coli, specifically the TolQ protein, not for adsorption or translocation, but rather at some unknown point during the phage particle maturation process. The addition of a T7 tag to the N-terminus of TolQ in Escherichia coli renders cells unable to support the infectious phage life cycle. The T7 tag addition also inhibits TolQ participation in processes necessary for maintenance of outer membrane integrity and its ability to participate in crosstalk with the paralogous TonB system. The T7 tag addition to the N-terminus of TolQ however, does not inhibit TolQ protein synthesis or the ability of the protein to serve its role in the translocation of group A colicins. These findings indicate an important role for the N-terminal region of TolQ in energy-dependent processes, one that is inhibited by the addition of the T7 tag. Additionally, a role for the Tol system proteins during the cell division process has been suggested. The T7 tag addition to TolQ does not lead to a chaining or filamentous growth pattern in E. coli cells. However, the overexpression of native TolQ does result in this morphological abnormality. This finding clearly supports past data indicating a role of TolQ during the cell division process, a role that is interrupted by the T7 tag addition to TolQ.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:e coli tolq colicin cell division p1
Date of Publication:01/01/2009