Solution NMR Structure and Functional Analysis of the Integral Membrane Protein YgaP from E. coli [Protein Structure and Folding]

June 23rd, 2014 by Eichmann, C., Tzitzilonis, C., Bordignon, E., Maslennikov, I., Choe, S., Riek, R.

The solution NMR structure of the α-helical integral membrane protein YgaP from Escherichia coli in mixed DHPC-7/LMPG micelles is presented. In these micelles, YgaP forms a homo-dimer with the two transmembrane helices being the dimer interface, while the N-terminal cytoplasmic domain comprises a rhodanese fold in accordance to its sequence homology to the rhodanese family of sulfurtransferases. The enzymatic sulfur-transfer activity of full-length YgaP as well as of the N-terminal rhodanese domain only was investigated performing series of titrations with sodium thiosulfate and potassium cyanide monitored by NMR and EPR. The data indicate the thiosulfate concentration-dependent addition of several sulfur atoms to the catalytic Cys63, which process can be reversed by the addition of potassium cyanide. The catalytic reaction induces thereby conformational changes within the rhodanese domain, as well as on the transmembrane α-helices of YgaP. These results provide insights into a potential mechanism of YgaP during the catalytic thiosulfate activity in vivo.