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SUMMARY:Molecular convergence in the evolution of betalains - Hester Sheeh
 an\, Brockington group
DTSTART:20191024T120000Z
DTEND:20191024T123000Z
UID:TALK131695@talks.cam.ac.uk
CONTACT:71002
DESCRIPTION:Betalains are pigments that produce a palette of pink\, purple
 \, yellow and orange colours. These specialised metabolites are fascinatin
 g from an evolutionary standpoint because betalains are mutually exclusive
  with the otherwise ubiquitous anthocyanin pigments and because they are f
 ound only in the plant order\, Caryophyllales. Betalains have a homoplasic
  distribution in the Caryophyllales and until recently it was thought that
  this pattern was explained by betalains having evolved once\, with multip
 le reversals occurring to anthocyanin pigmentation. However\, our work on 
 a key biosynthetic enzyme\, DODA\, shows that it is very likely that betal
 ains evolved at least three times and thus that they represent an example 
 of convergent evolution. I will present the work that led to this conclusi
 on\, which involved the functional characterization of DODA enzymes from a
  diverse range of betalain- and anthocyanin-pigmented Caryophyllales speci
 es. We also reconstructed functionally important amino acid sites across t
 he DODA phylogeny and found evidence for convergence at the molecular leve
 l. Using molecular convergence models and protein modeling to come up with
  candidate residues\, we plan to test these residues using a yeast heterol
 ogous assay to determine the extent of molecular convergence between the d
 ifferent origins. Ultimately\, we hope to determine the critical mutations
  that allowed an enzyme to specialize on a different substrate and assist 
 in producing a novel class of plant pigments.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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