Speaker
Description
The multivesicular sorting machinery is a crucial mechanism for targeting membrane proteins
for recycling or degradation. The lysosomal trafficking regulator-interacting protein 5 (LIP5)
which coordinates the action of this machinery is also known to bind directly to the membrane
protein cargo. In case of aquaporin 2 (AQP2) the binding of LIP5 during the endocytic pathway
in kidney collecting duct cells ensures an effective regulation of urine volume [1].
In our group, we have previously studied the role of AQP2 phosphorylation in AQP2-LIP5
interaction [2]. Currently we are focusing on elucidating the structural details of the complex
in order to better understand how membrane proteins are delivered to the multivesicular
bodies. We have constructed alanine mutants of single residues in the proposed binding sites
of both AQP2 and LIP5. Studying the binding affinity of these mutants using fluorescence
quenching helps us understand which residues are directly involved in the binding.
Further, AQP2 was successfully incorporated into MSP-based nanodiscs and negative stain
electron microscopy confirmed homogeneous state of the particles. We have collected high
resolution images on Titan Krios and are currently processing the data.
[1] B. W. M. Van Balkom, M. Boone, G. Hendriks, E. Kamsteeg, J. H. Robben, H. C. Stronks, A.
Van Der Voorde, and F. Van Herp, “LIP5 Interacts with Aquaporin 2 and Facilitates Its
Lysosomal Degradation,” pp. 990–1001, 2009.
[2] J. V. Roche, S. Survery, S. Kreida, V. Nesverova, H. Ampah-Korsah, M. Gourdon, P. M. T.
Deen, and S. Törnroth-Horsefield, “Phosphorylation of human aquaporin 2 (AQP2)
allosterically controls its interaction with the lysosomal trafficking protein LIP5,” J. Biol.
Chem., vol. 292, no. 35, pp. 14636–14648, 2017.
