Discussion about this post

User's avatar
Calypso's avatar

"2. If the promoter is contained on a segment, then it will actively move the segment into the nucleus."

Perhaps you mean the SV40 enhancer. This contains a 72bp sequence that supposedly binds with proteins native to the cell and the entire piece of DNA is actively transported to the nucleus and actively imported thru the nuclear pores. This means that a whole plasmid will be moved into the nucleus, or any smaller fragments that contain this SV40 enhancer sequence.

But the vast majority of this DNA contamination appears to be small fragments that can freely diffuse practically anywhere in the cell, including into the nucleus. This makes the "nuclear localization sequence" less interesting, because most of the DNA can get there anyway without it.

"3. It will be as likely as any other segment to cause problems once it is incorporated into a chromosome."

There is an argument that an insertion mutation containing a strong promoter element is worse than other random sequences, because it could create an open reading frame wherever it may insert, or just cause over-expression of a gene in whole or in part. But if the majority of the DNA contamination is around 50-200bp fragments, whole promoters won't typically remain intact, and therefore the simple disruption of normal genome sequence is the biggest hazard here.

Expand full comment
1 more comment...

No posts