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Volume 10, Issue 8 (Suppl) J Proteomics Bioinform, an open access journal
ISSN: 0974-276X Structural Biology 2017
September 18-20, 2017
9th International Conference on
Structural Biology
September 18-20, 2017 Zurich, Switzerland
Construction of structural mimetics of the thyrotropin receptor intracellular domain
Stanislav Engel
Ben-Gurion University, Israel
Background: Dissecting G protein-coupled receptors (GPCR) signaling in terms of the pathways being activated will boost
our understanding of the molecular fundamentals of hormone action. The structural determinants governing the selectivity
of GPCR/G protein coupling, however, remain obscure. The selectivity of GPCR/G protein recognition appears to be
determined by both specific inter-residue interactions and features related to the overall 3D conformation of the ICD. It
appears, therefore, that to elucidate the fundamentals of the selectivity of GPCR/G protein recognition, a comprehensive
analysis of the structure-activity relationships of multiple GPCR complexes with different G protein isoforms is required.
However, enormous technical difficulties associated with the isolation of functional receptors in quantities required for direct
structural studies effectively impede progress in the field.
Methodology: We constructed the functional mimetics of the intracellular domain (ICD) of a model GPCR - thyrotropin
receptor (TSHR), based on a unique scaffold, 6-Helix, an artificial protein that was derived from the elements of the trimer-
of-hairpins structure of HIV gp41 and represents a bundle of six α-helices.
Findings: The 6-Helix scaffold, which endowed the substituted TSHR ICD elements with spatial constraints analogous to
those, found in native receptors, enabled the reconstitution of a microdomain comprising the intracellular loops ICL-2 and
ICL-3, which is capable of binding and activating G α-(s).
Conclusion & Significance: By using a soluble scaffold, which furnishes peptides derived from the GPCR ICD with spatial
constraints similar to those, found in native receptors, the reconstitution of a native-like G protein-recognition epitope can
be facilitated. The 6-Helix-based mimetics could be used as a platform to study the molecular basis of GPCR/G protein
recognition. Such knowledge could lead to the development of novel therapeutic strategies for GPCR-related disorders by
targeting the GPCR/G protein interfaces and help counteract cellular dysfunctions via focused tuning of GPCR signaling.
Biography
Stanislav Engel PhD, is an Assistant Professor in the Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, The National Institute
for Biotechnology, Ben-Gurion University in the Negev, Beer-Sheva, Israel. He got his BSc in Biochemistry, MSc and PhD in Biochemistry and Biotechnology
Engineering at the Ben-Gurion University in the Negev. Currently, his researches focus on understanding the structural basis of “protein misfolding” diseases, such
as ALS, and structure-based drug discovery.
Stanislav Engel et al., J Proteomics Bioinform 2017, 10:8(Suppl)
DOI: 10.4172/0974-276X-C1-0100
Figure1: The three conformational states of the KpCitS
dimer. (a) Schematic representation of the KpCitS
protomer. Two helical hairpins of the transport domain
are highlighted in purple. (b) The homodimeric KpCitS
structure in different functional states viewed from the
membrane plane (top) and from the periplasm (bottom).
Citrate is shown as an orange ball-and-stick model.
The black oval is a pseudo 2-fold axis, perpendicular
to the membrane.