As I am working through my lab experiments I am reading as much as I can to understand all the details in DNA uptake. One of the papers I am reading is review of Krüger and Stingl in 2011. In paper there are several arguments that I think are not clear or are confusing. First, authors use as a counterargument against DNA been attaching to the retracting pili; their argument is that pilT (protein in pili retraction) was not essential for transformation in Pseudomonas. But what about Haemophilus? it does even has pilT and the pili retracts normally?.
I also getting confused with the roles of pilQ/ComE, ComEA/E1 and comP. This review states that pilQ bind to DNA and ComE pulling DNA across the outer membrane. However, I think authors are confused between initiation of uptake and continuation of uptake. How does comE would pull DNA across the outer membrane if DNA if comE is a periplasmic protein and the DNA is still outside of the cell? I can not even imagine how DNA would enter the cell through the narrow pore of pilQ/ComE if it is not pulled in by the retracting pili.
The paper also states that DNA is diffused though the cell wall once the pseudopilus open a hole in gram positive bacteria. This idea also seems very unlikely. Can gDNA diffuse easily through a 55nm hole?
I found some old posts of Rosie that are helping me understand this process