Andreas Franz
DAAD RISE worldwide undergraduate intern in 2014, Pharmacology
Third year undergraduate in Biochemistry (B.Sc.), Free University of Berlin, Germany
Papers form the lab
Vishnivetskiy SA, Lee RJ, Zhou XE, Franz A, Xu Q, Xu HE, Gurevich VV. Functional role of the three conserved cysteines in the N-domain of visual arrestin-1. J Biol Chem, in press, (2017)
Research Description
Under the supervision of Dr. Sergey Vishnivetskiy, Andreas focused on elucidating the structural properties of the visual arrestin-1 and its conformational changes upon binding to different forms of rhodopsin. Arrestin is often seen as a static protein, but our research indicates that it is indeed flexible and that this flexibility has a strong influence on its binding capabilities. To further elucidate this, Andreas constructed several cysteine-free versions of pre-activated bovine visual arrestin-1 and performed in vitro transcription and translation. He then tested the affinity of the synthesized mutant proteins to different forms of rhodopsin in an in vitro binding assay. Interestingly, his results show that the substitution of the three native cysteins in arrestin-1 with two hydrophobic amino acids (alanine and/or valine) and one hydrophilic serine, can have a strong influence on the binding capabilities of arrestin. In this case, it almost eliminated the activating effect of the two pre-activation mutations.
Comparing the crystal structure of free arrestin and the complex of arrestin-2 with a posphopeptide derived from human vasopressin V2 receptor, it was hypothesized that the C- and N-domain of arrestins twist relative to each other upon binding to their correspondent receptor, enabling new residues to interact with the GPCR. To prove that this proposed conformational change also holds true for arrestin-1 and the phosphorylated, light activated rhodopsin under natural conditions, Andreas introduced two double cysteine substitutions in the visual arrestin-1. After protein purification, these cysteins will be chemically modified and the mutant proteins used for EPR spectroscopy to measure the distances between the modified residues. Because the introduced cysteins are located in both the C- and the N-domain, structural changes, such as a twist of these domains, can be detected.
Paper from the lab
Vishnivetskiy, S.A., Lee, R.J., Zhou, X.E., Franz, A., Xu, Q., Xu, H.E., Gurevich, V.V. Functional role of the three conserved cysteines in the N-domain of visual arrestin-1. J Biol Chem, 292 (30), 12496-12502; doi: 10.1074/jbc.M117.790386 (2017).