BIO: questions about GFP and CaM

[subwaybusker]

Homework Statement

The molecule in question is GFP with CaM
1) Suggest several point mutations that will disable the protein's function without dramatically altering the protein's shape. Explain why.
2) Suggest a point mutation that will completely alter the protein's shape. Explain why.

Homework Equations

The Attempt at a Solution

1) I'm guesssing the main function of the protein right now is to detect Ca2+. I read somewhere else that it can detect certain proteins afterwards too, but I'm not sure which is more accurate...so I think mutating CaM at the Ca2+ binding site by changing the negative amino acids to positive ones will work? Again, I'm not exactly sure what the point mutations are on the EF hand...and I'm not sure whether that will change the shape by a lot...
2) a single point deletion will cause a frameshift mutation (i'm not sure if this counts as a point mutation though?) which will cause a different sequence of amino acids to be linked, hence the shape will be very different.

 

[nate808]

1) One possible point mutation that could disable the protein's function without dramatically altering its shape is replacing a non-essential amino acid with a different one. This would not significantly change the protein's shape, but it could disrupt the protein's ability to bind to Ca2+. For example, replacing a polar amino acid with a non-polar one at the Ca2+ binding site could prevent the protein from properly interacting with Ca2+ ions. Additionally, mutating amino acids that are involved in the protein's secondary structure, such as those in alpha helices or beta sheets, could also disrupt its function without drastically changing its shape.

2) A point mutation that could completely alter the protein's shape is a substitution of an amino acid with a significantly different chemical property. For example, replacing a hydrophobic amino acid with a hydrophilic one could significantly change the protein's interactions with its environment and alter its shape. This could potentially disrupt the protein's function, as the new shape may not be able to properly bind to Ca2+ or other proteins. Additionally, a point mutation that results in a premature stop codon could also drastically alter the protein's shape, as it would result in a truncated protein with a different sequence of amino acids.

 

[Blueshift5]

Another option is to change a key amino acid in the beta barrel structure of GFP, which will disrupt the folding and alter the overall shape of the protein.