title: Membrane protein crystallization in micelles conjugated by nucleoside base-pairing: A different concept.
abstract: The dearth of high quality, three dimensional crystals of membrane proteins, suitable for X-ray diffraction analysis, constitutes a serious barrier to progress in structural biology. To address this challenge, we have developed a new crystallization medium that relies on the conjugation of surfactant micelles via base-pairing of complementary hydrophobic nucleosides. Base-pairs formed at the interface between micelles bring them into proximity with each other; and when the conjugated micelles contain a membrane protein, crystal nucleation centers can be stabilized, thereby promoting crystal growth. Accordingly, two hydrophobic nucleoside derivatives - deoxyguanosine (G) and deoxycytidine (C), each covalently bonded to a 10 carbon chain were synthesized and added to an aqueous solution containing octyl β-d-thioglucopyranoside micelles. These hydrophobic nucleosides induced the formation of oil-rich globules after 2days incubation at 19°C or after a few hours in the presence of ammonium sulfate; however, phase separation was inhibited by 100mM GMP. The presence of the membrane protein bacteriorhodopsin in the conjugated - micellar dispersion resulted in the growth within the colorless globules of a variety of purple crystals, the color indicating a functional protein. On this basis, we suggest that conjugation of micelles via base-pair complementarity may provide significant assistance to the structural determination of integral membrane proteins.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India.
authors.forename: Basavaprabhu
authors.initials: B
authors.lastname: Hosamani
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India.
authors.forename: Raju R
authors.initials: RR
authors.lastname: Kale
authors.affiliation: Department of Chemical Sciences, Ariel University, 70400 Ariel, Israel.
authors.forename: Hemlata
authors.initials: H
authors.lastname: Sharma
authors.affiliation: Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Ellen
authors.initials: E
authors.lastname: Wachtel
authors.affiliation: Department of Biotechnology and Food Engineering, Technion, Haifa 32000, Israel.
authors.forename: Ellina
authors.initials: E
authors.lastname: Kesselman
authors.affiliation: Department of Biotechnology and Food Engineering, Technion, Haifa 32000, Israel.
authors.forename: Dganit
authors.initials: D
authors.lastname: Danino
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Noga
authors.initials: N
authors.lastname: Friedman
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Mordechai
authors.initials: M
authors.lastname: Sheves
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India. Electronic address: irishi@iitb.ac.in.
authors.forename: Irishi N N
authors.initials: INN
authors.lastname: Namboothiri
authors.affiliation: Department of Chemical Sciences, Ariel University, 70400 Ariel, Israel. Electronic address: guyp@ariel.ac.il.
authors.forename: Guy
authors.initials: G
authors.lastname: Patchornik
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry; D020029:Base Pairing; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D003841:Deoxycytidine / Q000737:chemistry*; D003849:Deoxyguanosine / Q000737:chemistry*; D008823:Micelles
chemical_list: D008823:Micelles; D003841:Deoxycytidine; D001436:Bacteriorhodopsins; D003849:Deoxyguanosine