Wednesday, April 12, 2017 - 3:30pm
Smart Room, 5th Floor, SBASSE Building
SBASSE Biology Talk 2017
How smart proteins make bacteria monsters: A solid-state NMR study
Guest Speaker: Dr. Shakeel Ahmad Shahid
Date: Wednesday, April 12, 2017
Time: 3:30 pm – 4:30 pm
Venue: Smart Room, 5th Floor, SBASSE Building
Host: Dr. Syed Shahzad Ul Hussan
Abstract
Yad A is an outer membrane protein from Yersinia enterocolitica and a member of trimeric autotransporter adhesins. Its transmembrane anchor domain (YadA-M) forms a highly stable trimeric beta-barrel and is conserved throughout the family. It plays a role as autotransporter, where it transports its own N-terminal domain through the membrane to form a head group that adheres to the host cell. This adherence is the first step in causing several enteric food borne diseases, ranging from diahrrea to autoimmune disorders. The trimeric membrane anchor domain of Yad A contains 315 residues. We were able to completely (ca. 97%) assign the YadA-M using using a set homo- and heteronuclear correlation spectra. Various homo- and heteronuclear multidimensional NMR spectra were used to gather secondary and tertiary structure information. A de novo structure of the beta barrel membrane protein was obtained on the basis of MAS solid-state NMR data. In my talk, I would present some functional aspects and an extremely smart trick of YadA-M protein by which it makes bacteria infectious. From the study it was found that a quartet of helical residues (named the “ASSA” region) displays random-coil like chemical shifts, low order-parameters, reduced helix propensity, and a drop in signal intensity pointing towards a relatively increased flexibility. Based on combined structural and evolutionary studies, our work is in strong favour of the ‘hairpin model’ as mechanism of the autotransport through a narrow beta barrel. Based upon these findings we carried out point mutation studies in the ASSA region that resulted into marked structural changes. In the end, I would show how we carried out a first successful attempt of studying a membrane protein into the real bacterial outer-membrane fraction by solid-state NMR.
Profile
Research scientist in Structural Biochemistry with expertise in structural studies of membrane proteins by solid- and solution state NMR. Specialist in membrane protein overexpression, purification and reconstitution into Phospholipid Bilayer Nanodiscs.
Affiliation: Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin & Max-Planck-Institute München and Institute for Advance study (IAS), TUM
Selected Publications
Shahid, S.A., et al., Membrane-protein structure determination by solid-state NMR spectroscopy of microcrystals. Nature methods, 2012. 9(12): p. 1212-U119.
Shahid, S.A., et al., Solid-state NMR study of the YadA membrane domain in the bacterial outer membrane. Angew. Chem. Int. Ed. Engl. 54(43) August 2015
