Difference between revisions of "Part:BBa K2118002"

Latest revision as of 09:20, 13 October 2020

FMS1 gene

Polyamine oxidase FMS1 gene is original from Saccharomyces Cerevisae. It encodes for a protein which is involved in polyamine degradation, specifically spermine and spermidine. It catalyses the oxidation of both polyamines and it yields to lower chain amines (spermidine and putrescine respectively) and other compounds: 3-aminopropanal and hydrogen peroxide.

Warwick iGEM 2020 - Enzyme kinetics of FMS1

The kinetics of FMS1 are relatively well understood, as well as its substrate specificites. Its catalytic activity goes through two halves, due to the fact that its cofactor, FAD[2], is reduced through an irreversible step, in which the substrate is also oxidised. From there, the product can either disengage from the reduced enzyme-product complex, or the whole complex can be reoxidised, after which the product disengages from the oxidised enzyme-FAD complex, restoring the enzyme and the cofactor. The rate constant for both release reactions are much lower than the rate constant for oxidisation of the substrate (4,5 s-1 and 56,5 s-1, respectively, as opposed to 126 s-1), therefore the RDS of the whole reaction is the product release step.

The specificity of the enzyme is hinted at by the fact that the enzyme operates at maximum efficiency in acidic environments (around pH = 9). This means that at least one of the amino groups has to be protonated for its activity; indeed, it has been shown that acetylating the N1 amino group actually slightly increases the catalytic rate constant. Since the N4 amino group is the oxidation site in N1-acetylspermine, and knowing that said amino group must be unprotonated for the reaction to occur, it is very likely that N9 and N12 must be protonated in the active form. This is supported by the three dimensional structure of the enzyme with a spermine molecule docked, which would suggest an interaction between N12 and Asp94's side chain. The oxidisation site is likely kept unprotonated by a nearby histidine residue (either His67 or His191)[1].

In vivo, this enzyme is important in panthothenic acid biosynthesis, as spermine is oxidised to 3-aminopropanal, which is then converted to β-alanine, a precursor to pantothenic acid. This makes it crucial to the energy metabolism, since pantothenate is the starting point for synthesis of coenzyme A.

Sources: [1] - Adachi, M. S., Torres, J. M., Fitzpatrick, P. F., Mechanistic Studies of the Yeast Polyamine Oxidase Fms1: Kinetic Mechanism, Substrate Specificity, and pH dependence, Biochemistry, 2010, 49, 10440-10449, doi: 10.1021/bi1016099
[2] - Landry, J., Sternglanz, R., Yeast Fms1 is a FAD-utilising polyamine oxidase, Biochemical and Biophysical Research Communications, 2003, 303, 771-776, doi: https://doi.org/10.1016/S0006-291X(03)00416-9

Sequence and Features