a question about gene expression in plasmids

Nick Theodorakis nick_theodorakis at hotmail.com
Mon Dec 15 20:28:53 EST 2003

On 15 Dec 2003 08:10:35 -0800, dikla_dar at walla.co.il (diki) wrote:

>nick_theodorakis at hotmail.com (Nick Theodorakis) wrote in message news:<3fdd17bf.48862163 at netnews.worldnet.att.net>...
>> On 14 Dec 2003 13:45:21 -0800, dikla_dar at walla.co.il (diki) wrote:
>> >hi everybody!
>> >my question is: in the plasmid pBR322, 
>> Wow! Blast from the past.!
>> >if I replace the whole gene for
>> >resistance to amp. in a certain insert, is there a good chance that
>> >the new gene will be expressed as a protein?
>> Depends. You got an E coli promoter on that insert?
>> > what are the
>> >circumstances in which it will happen? thank u very much for
>> >answering, diki.
>> There are a lot better vectors these days to express proteins in coli.
>> Or is this an exam question?
>> Nick
>hi! and thank u for answering.
>yes, u got it wright, this is an exam question...
>the question doesn't say which insert it is and whar I realy don't
>understand is what factor determines whether the insert will or will
>not be expressed.

The question is not really complete. If you replace "the whole gene"
for amp resistance, to me that means you deleted the promoter for it
as well. So your insert should need a promoter active in E coli to be
expresed, and a Shine-Dalgarno sequence at an appropriate location
will help as well.


Nick Theodorakis
nick_theodorakis at hotmail.com
nicholas_theodorakis [at] urmc [dot] rochester [dot] edu 

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