13 September 2019

Congratulations Nikolai!

PhD Defence

Friday September 13th DynaMo PhD scholar Nikolai Wulff successfully defended his PhD thesis and was awarded the PhD degree.

In front of colleagues, family and friends Nikolai Wulff successfully defended her PhD thesis entitled: Unravelling the Transport Mechanism of NPF Transporters.

Nikolai with the traditional PhD hat and after the defence with his supervisor Associate Professor Hussam Nour-Eldin

The overall objective of Nikolai’s PhD project was to study the relationship between structure and function in the NPF family of plant transporters.

He employed two major approaches. 

  1. An NPF family-wide screen for GA transport activity determined the gibberellin transport activity map and enabled correlation of activity to a 51-residue motif that comprises all potential substrate-interacting residues in the binding cavity. This work reduced the number of potential GA transporters in the NPF from 25 to 10 transporters, identified several residues that may control preference towards GA molecules and -based on their loose conservation- indicated that GA transport is promiscuous in the NPF. The reduced number of potential GA transporters greatly facilitates physiological studies of GA transport and the characterization of the substrate-binding cavity lays a foundation for structure-function investigation of the plant NPF.
  2. In the second approach, NW used the triplet of glucosinolate transporters GTR1-3 as model system to study structure-function in the NPF. He used a gain-of-function mutational approach. Based on bioinformatics analyses, NW identified 16 residues that are conserved differently in the substrate-binding cavity in GTR3 orthologs vs GTR1/2 orthologs. NW then pursued a rational mutational approach that identified 9 residues that when mutated simultaneously convert the narrow GTR3 substrate preference into the broad preference of GTR1/2. Putting these residues into a structural context revealed a hydrophobic pocket that may accommodate the non-polar side chain of aliphatic glucosinolates. This result represents the first -experimentally validated-identification of residues involved in recognizing organic molecules by plant NPFs. After his defence Nikolai will continue as a researcher at the Novo Nordisk Foundation Center for Protein Resarch at the University of Copenhagen.

Nikolai Wulff holds a BSc and an MSc in Biochemistry from the University of Copenhagen before he started as  a PhD student at DynaMo Center in April 2016 with Associate Professor Hussam H. Nour-Eldin as main-supervisor.

Congratulations Nikolai!