2eqb: Difference between revisions

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==Overview==

Vesicular transport during exocytosis is regulated by Rab GTPase (Sec4p in, yeast), which is activated by a guanine nucleotide exchange factor (GEF), called Sec2p. Here, we report the crystal structure of the Sec2p GEF, domain in a complex with the nucleotide-free Sec4p at 2.7 A resolution., Upon complex formation, the Sec2p helices approach each other, flipping, the side chain of Phe-109 toward Leu-104 and Leu-108 of Sec2p. These three, residues provide a hydrophobic platform to attract the side chains of, Phe-49, Ile-53, and Ile-55 in the switch I region as well as Phe-57 and, Trp-74 in the interswitch region of Sec4p. Consequently, the switch I and, II regions are largely deformed, to create a flat hydrophobic interface, that snugly fits the surface of the Sec2p coiled coil. These drastic, conformational changes disrupt the interactions between switch I and the, bound guanine nucleotide, which facilitates the GDP release. Unlike the, recently reported 3.3 A structure of the Sec4p.Sec2p complex, our, structure contains a phosphate ion bound to the P-loop, which may, represent an intermediate state of the nucleotide exchange reaction.

Vesicular transport during exocytosis is regulated by Rab GTPase (Sec4p in yeast), which is activated by a guanine nucleotide exchange factor (GEF) called Sec2p. Here, we report the crystal structure of the Sec2p GEF domain in a complex with the nucleotide-free Sec4p at 2.7 A resolution. Upon complex formation, the Sec2p helices approach each other, flipping the side chain of Phe-109 toward Leu-104 and Leu-108 of Sec2p. These three residues provide a hydrophobic platform to attract the side chains of Phe-49, Ile-53, and Ile-55 in the switch I region as well as Phe-57 and Trp-74 in the interswitch region of Sec4p. Consequently, the switch I and II regions are largely deformed, to create a flat hydrophobic interface that snugly fits the surface of the Sec2p coiled coil. These drastic conformational changes disrupt the interactions between switch I and the bound guanine nucleotide, which facilitates the GDP release. Unlike the recently reported 3.3 A structure of the Sec4p.Sec2p complex, our structure contains a phosphate ion bound to the P-loop, which may represent an intermediate state of the nucleotide exchange reaction.

==About this Structure==

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==Reference==

Crystal structure of the Sec4p~~{middle dot}~~Sec2p complex in the nucleotide exchanging intermediate state., Sato Y, Fukai S, Ishitani R, Nureki O, Proc Natl Acad Sci U S A. 2007 May 15;104(20):8305-10. Epub 2007 May 8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17488829 17488829]

Crystal structure of the Sec4p.Sec2p complex in the nucleotide exchanging intermediate state., Sato Y, Fukai S, Ishitani R, Nureki O, Proc Natl Acad Sci U S A. 2007 May 15;104(20):8305-10. Epub 2007 May 8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17488829 17488829]

[[Category: Protein complex]]

[[Category: Saccharomyces cerevisiae]]

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[[Category: coiled coil]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-Vesicular transport during exocytosis is regulated by Rab GTPase (Sec4p in, yeast), which is activated by a guanine nucleotide exchange factor (GEF), called Sec2p. Here, we report the crystal structure of the Sec2p GEF, domain in a complex with the nucleotide-free Sec4p at 2.7 A resolution., Upon complex formation, the Sec2p helices approach each other, flipping, the side chain of Phe-109 toward Leu-104 and Leu-108 of Sec2p. These three, residues provide a hydrophobic platform to attract the side chains of, Phe-49, Ile-53, and Ile-55 in the switch I region as well as Phe-57 and, Trp-74 in the interswitch region of Sec4p. Consequently, the switch I and, II regions are largely deformed, to create a flat hydrophobic interface, that snugly fits the surface of the Sec2p coiled coil. These drastic, conformational changes disrupt the interactions between switch I and the, bound guanine nucleotide, which facilitates the GDP release. Unlike the, recently reported 3.3 A structure of the Sec4p.Sec2p complex, our, structure contains a phosphate ion bound to the P-loop, which may, represent an intermediate state of the nucleotide exchange reaction.
+Vesicular transport during exocytosis is regulated by Rab GTPase (Sec4p in yeast), which is activated by a guanine nucleotide exchange factor (GEF) called Sec2p. Here, we report the crystal structure of the Sec2p GEF domain in a complex with the nucleotide-free Sec4p at 2.7 A resolution. Upon complex formation, the Sec2p helices approach each other, flipping the side chain of Phe-109 toward Leu-104 and Leu-108 of Sec2p. These three residues provide a hydrophobic platform to attract the side chains of Phe-49, Ile-53, and Ile-55 in the switch I region as well as Phe-57 and Trp-74 in the interswitch region of Sec4p. Consequently, the switch I and II regions are largely deformed, to create a flat hydrophobic interface that snugly fits the surface of the Sec2p coiled coil. These drastic conformational changes disrupt the interactions between switch I and the bound guanine nucleotide, which facilitates the GDP release. Unlike the recently reported 3.3 A structure of the Sec4p.Sec2p complex, our structure contains a phosphate ion bound to the P-loop, which may represent an intermediate state of the nucleotide exchange reaction.
 ==About this Structure==
@@ Line 10: / Line 10: @@
 ==Reference==
-Crystal structure of the Sec4p{middle dot}Sec2p complex in the nucleotide exchanging intermediate state., Sato Y, Fukai S, Ishitani R, Nureki O, Proc Natl Acad Sci U S A. 2007 May 15;104(20):8305-10. Epub 2007 May 8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17488829 17488829]
+Crystal structure of the Sec4p.Sec2p complex in the nucleotide exchanging intermediate state., Sato Y, Fukai S, Ishitani R, Nureki O, Proc Natl Acad Sci U S A. 2007 May 15;104(20):8305-10. Epub 2007 May 8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17488829 17488829]
 [[Category: Protein complex]]
 [[Category: Saccharomyces cerevisiae]]
@@ Line 20: / Line 20: @@
 [[Category: coiled coil]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 14:57:33 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:13:33 2008''