Protocol Online logo
Top : New Forum Archives (2009-): : Molecular Biology

Amino acid substitution a problem? - Phenylalanine to leucine (Aug/18/2009 )

Are there any obvious reasons a mutation of DNA resulting in a Phe > Leu substitution would raise a flag? Both are non-polar, neutral amino acids. Is there anything in their biochemistry that would immediately tell you that a protein would fold or act differently?

The reason I'm asking is because I have a complementation plasmid, and the gene carried has a point mutation in it. It makes a UAC into a UAA.

I'm likely to go ahead and remake it, but was curious, considering some of the properties of the two bases are similar.

-fishdoc-

fishdoc on Aug 19 2009, 03:20 PM said:

Are there any obvious reasons a mutation of DNA resulting in a Phe > Leu substitution would raise a flag? Both are non-polar, neutral amino acids. Is there anything in their biochemistry that would immediately tell you that a protein would fold or act differently?

The reason I'm asking is because I have a complementation plasmid, and the gene carried has a point mutation in it. It makes a UAC into a UAA.

I'm likely to go ahead and remake it, but was curious, considering some of the properties of the two bases are similar.

You're right to say the two are similar. Having said that, however, you are going from an aromatic residue to a non-aromatic. As long as the residue isn't somewhere critical, there is no prior reason to say there would be a problem. Is that non-committal enough? ;)

-swanny-

if you are curious, you could do your biochemical assay on both the mutant and normal form of the protein.

There is the size of the side group to consider aside from change from aromatic to non aromatic side groups. Uncertain to say if will be an effect.

-perneseblue-

I would do an alignment of homologous proteins in ClustalW and see if the Phe residue was conserved. If it were, then I would remake it. This is the best way of determining if an amino acid is in a critical site. This is not a guarantee of functionality, but it is likely a near requirement for functionality.

-phage434-