Comparing those expression hosts, they all have pros and cons. I know that it all depends on what proteins we are going to express. However, Is there general rule on how to chose a good expression host?
Daniel, just to add to what's been said, here are some important questions to consider.
1. What amount of protein do you need, and for what purpose? Is your aim to grow a crystal, or perform biochemical characterization, or to raise an antibody?
2. What is the species your protein of interest originated from and what systems have people working on the same or related proteins successfully used to express it? Certain eukaryotic proteins will not fold correctly in bacteria for example, while S. cerevisiae will frequently glycosylate proteins post-translationally, which may not be desirable for your purposes or may harm the yield. An insect or mammalian cell expression system may give you protein that is closest in form to what you are studying, if it originated from humans or mice.
3. What can you afford to use in your lab? Bacteria are cheap to culture in large amounts but if you have to go with a mammalian cell system, it may prove to be fairly expensive.
Those are just to get you started. Good luck!
Posttranslational modifications of your protein of interest should be taken into account e.g. glycosylation.
Here is a paper on protein production in E. coli.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609253/pdf/apjtb-02-02-159.pdf
It depends on what is the purpose of the expressed protein for. Some you can just use bacteria for expression system, some need to pay attention for the expression system. Such as production of antibody or some kind of protein drugs for, for example, human use, the post-translational modification is an important consideration as mentioned by Agnieszka.
Daniel, just to add to what's been said, here are some important questions to consider.
1. What amount of protein do you need, and for what purpose? Is your aim to grow a crystal, or perform biochemical characterization, or to raise an antibody?
2. What is the species your protein of interest originated from and what systems have people working on the same or related proteins successfully used to express it? Certain eukaryotic proteins will not fold correctly in bacteria for example, while S. cerevisiae will frequently glycosylate proteins post-translationally, which may not be desirable for your purposes or may harm the yield. An insect or mammalian cell expression system may give you protein that is closest in form to what you are studying, if it originated from humans or mice.
3. What can you afford to use in your lab? Bacteria are cheap to culture in large amounts but if you have to go with a mammalian cell system, it may prove to be fairly expensive.
Those are just to get you started. Good luck!
The advantages of bacteria are speed and cheap production. Thus it's usually the first choice. On the other hand, they lack most of the PTMs, as mentioned, there can be problems with the production (transmembrane proteins, disulfides, but with those it can be dealt with, or just simply it doesn't work), also they can contain some toxins which jeopardize the usage in humans.
Yeasts are slower, but the yields are usually higher and they contain PTMs, however, sometimes you can encounter e.g. hyperglycosylation. If that's problem, you need to go into system more resembling your origin species, i.e. animal or plant cell suspensions. In those you can expect the handling of the gene to resemble almost identically to that in the original species.
A cell-free, in vitro translation system may also be useful if you are having trouble with in vivo expression of your protein, if it can generate the required yield for your purpose.
For the proper posttranslational modifications also insect cells might be an option (e.g. from spodoptera frugiperda). I worked a lot with this expression system, it is of course not as easy as the work with bacteria but for many projects it might still be the better option.
Depends on the protein you're trying to express, obviously. In general though, if you're just starting and you have no idea about how soluble/insoluble your construct is, and/or you want a large volume, I'd personally start with bacteria. Mainly because of how much easier they are to work with.
The major factor in choosing an expression host is based on whether you want post-translational modifications or not. If you don't want PTM, bacteria is the obvious choice. This is of course used for many bacterial proteins. However, if you want the expression of a protein with PTM, you have to choose animal cells or insect cells or even yeast cells. If your protein is from a human gene, it is better to go with animal cells like CHO or HEK cells.
Hi Deepak,
I wanted to qualify your statement; bacteria do actually carry out post-translation modifications of proteins, including phosphorylation, although the nature of the modifications does differ.
http://www.ncbi.nlm.nih.gov/pubmed/23994099
You make a good point about employing an expression system that is closely related to the species that your protein of interest originated from when PTMs are important.
Hey Mark,
Thanks for the information. I was not sure about that, but now I am clear after you shared it.
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