recombinant protein expression- surface or internal? - (Aug/18/2015 )

Hi guys, 

 

I am trying to clone a foreign dna into a particular plasmid. And electro-transformed into lactobacillus for expression.

 

This is a novel study using lactobacillus species so I do not know whether it will expressed on the surface or internal of bacterium.

 

My question is how do we normally predict (NOT determine) the localization of expressed protein if only based on literature review? 

 

1. Does it based on the protein produced (size, structure, etc)? Or

2. Does it based on the plasmid vector (promoter sequence etc)? Or

3. Does it based on the bacteria strain itself? 

 

Hope someone can enlighten me on this. Thanks.

Meg P. Anula on Tue Aug 18 06:15:02 2015 said:

Hi guys, 

 

I am trying to clone a foreign dna into a particular plasmid. And electro-transformed into lactobacillus for expression.

 

This is a novel study using lactobacillus species so I do not know whether it will expressed on the surface or internal of bacterium.

 

My question is how do we normally predict (NOT determine) the localization of expressed protein if only based on literature review? 

 

1. Does it based on the protein produced (size, structure, etc)? Or

2. Does it based on the plasmid vector (promoter sequence etc)? Or

3. Does it based on the bacteria strain itself? 

 

Hope someone can enlighten me on this. Thanks.

 

1. Yes

2. Yes

3. Yes

 

This will help a lot eh? 

 

Now to answer a bit more:

 

1. It does indeed depend on the structure. Proteins often have structures that will be directed to a membrane (just to give an example). They can have a signal molecule ... They can be altered to be send to place X

 

2. Yes: if you design a vector and , for example, add a nucleus localization signal, it will be directed to the nucleus, you also add something to tag it to the cell wall...

 

3. yeah, can also be of importance..

 

 

Your question is very wide and it can depend on so many things!

Thanks Pito for the answer.

 

Let me recap. Let say literature reviews showed that:

 

1. my protein is an influenza virus antigen that's normally expressed on the surface of infected cells 

 

2. the plasmid I'm using has been used to recombine with other antigen, which is shown to be expressed on the surface of lactococcus species 

 

3. my expression bacteria, lactobacillus has been widely used to express many other proteins, on its surface 

 

Thus for my work, it's of high chance that it'll express on the surface (or both surface and internal). Am I right?

 

 

 

ps: is there any reference/books/links anyone can show me on the protein expression and localization process? I think I needa start on the basis.

Most likely the protein does indeed have some sort of singaling part to be expressed on the outside in normal situations.

You are however working with something artificial (bacteria, plasmid). However: it seems this has been taken care by 2 things; using a plasmid with a "gene/protein" that is expressed on the surface (anchor or something) + you use Lactobacillus, which, according to you, is used widely for this kind of work.

 

So I would guess: yeah, everything is present to express it on the outside...

 

I am not a virologist, but it does seem normal.

 

Your question about books: I can not think of any right now.

I am not really a protein expert myself.