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The Sec7 N-terminal regulatory domains facilitate membrane-proximal activation of the Arf1 GTPase.

Richardson BC, Halaby SL, Gustafson MA, Fromme JC - Elife (2016)

Bottom Line: We demonstrate that the established role of the N-terminal region in dimerization is not conserved; instead, a C-terminal autoinhibitory domain is responsible for dimerization of Sec7.We find that the DCB/HUS domain amplifies the ability of Sec7 to activate Arf1 on the membrane surface by facilitating membrane insertion of the Arf1 amphipathic helix.This enhancing function of the Sec7 N-terminal domains is consistent with the high rate of Arf1-dependent trafficking to the plasma membrane necessary for maximal cell growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States.

ABSTRACT
The Golgi complex is the central sorting compartment of eukaryotic cells. Arf guanine nucleotide exchange factors (Arf-GEFs) regulate virtually all traffic through the Golgi by activating Arf GTPase trafficking pathways. The Golgi Arf-GEFs contain multiple autoregulatory domains, but the precise mechanisms underlying their function remain largely undefined. We report a crystal structure revealing that the N-terminal DCB and HUS regulatory domains of the Arf-GEF Sec7 form a single structural unit. We demonstrate that the established role of the N-terminal region in dimerization is not conserved; instead, a C-terminal autoinhibitory domain is responsible for dimerization of Sec7. We find that the DCB/HUS domain amplifies the ability of Sec7 to activate Arf1 on the membrane surface by facilitating membrane insertion of the Arf1 amphipathic helix. This enhancing function of the Sec7 N-terminal domains is consistent with the high rate of Arf1-dependent trafficking to the plasma membrane necessary for maximal cell growth.

No MeSH data available.


Related in: MedlinePlus

MALS traces of S. cerevisiae and T. terrestris Sec7 constructs. Normalized gel filtration peak profiles of all Sec7 constructs are shown with MALS molecular weight measurements superimposed. The right-hand molecular weight axis for each panel is scaled to each construct’s calculated mass, with monomeric, dimeric, and trimeric masses indicated. Due to the wide variation in construct size, a single gel filtration column was not used for every construct, leading to the variation in elution profiles seen.DOI:http://dx.doi.org/10.7554/eLife.12411.011
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fig2s3: MALS traces of S. cerevisiae and T. terrestris Sec7 constructs. Normalized gel filtration peak profiles of all Sec7 constructs are shown with MALS molecular weight measurements superimposed. The right-hand molecular weight axis for each panel is scaled to each construct’s calculated mass, with monomeric, dimeric, and trimeric masses indicated. Due to the wide variation in construct size, a single gel filtration column was not used for every construct, leading to the variation in elution profiles seen.DOI:http://dx.doi.org/10.7554/eLife.12411.011


The Sec7 N-terminal regulatory domains facilitate membrane-proximal activation of the Arf1 GTPase.

Richardson BC, Halaby SL, Gustafson MA, Fromme JC - Elife (2016)

MALS traces of S. cerevisiae and T. terrestris Sec7 constructs. Normalized gel filtration peak profiles of all Sec7 constructs are shown with MALS molecular weight measurements superimposed. The right-hand molecular weight axis for each panel is scaled to each construct’s calculated mass, with monomeric, dimeric, and trimeric masses indicated. Due to the wide variation in construct size, a single gel filtration column was not used for every construct, leading to the variation in elution profiles seen.DOI:http://dx.doi.org/10.7554/eLife.12411.011
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764562&req=5

fig2s3: MALS traces of S. cerevisiae and T. terrestris Sec7 constructs. Normalized gel filtration peak profiles of all Sec7 constructs are shown with MALS molecular weight measurements superimposed. The right-hand molecular weight axis for each panel is scaled to each construct’s calculated mass, with monomeric, dimeric, and trimeric masses indicated. Due to the wide variation in construct size, a single gel filtration column was not used for every construct, leading to the variation in elution profiles seen.DOI:http://dx.doi.org/10.7554/eLife.12411.011
Bottom Line: We demonstrate that the established role of the N-terminal region in dimerization is not conserved; instead, a C-terminal autoinhibitory domain is responsible for dimerization of Sec7.We find that the DCB/HUS domain amplifies the ability of Sec7 to activate Arf1 on the membrane surface by facilitating membrane insertion of the Arf1 amphipathic helix.This enhancing function of the Sec7 N-terminal domains is consistent with the high rate of Arf1-dependent trafficking to the plasma membrane necessary for maximal cell growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States.

ABSTRACT
The Golgi complex is the central sorting compartment of eukaryotic cells. Arf guanine nucleotide exchange factors (Arf-GEFs) regulate virtually all traffic through the Golgi by activating Arf GTPase trafficking pathways. The Golgi Arf-GEFs contain multiple autoregulatory domains, but the precise mechanisms underlying their function remain largely undefined. We report a crystal structure revealing that the N-terminal DCB and HUS regulatory domains of the Arf-GEF Sec7 form a single structural unit. We demonstrate that the established role of the N-terminal region in dimerization is not conserved; instead, a C-terminal autoinhibitory domain is responsible for dimerization of Sec7. We find that the DCB/HUS domain amplifies the ability of Sec7 to activate Arf1 on the membrane surface by facilitating membrane insertion of the Arf1 amphipathic helix. This enhancing function of the Sec7 N-terminal domains is consistent with the high rate of Arf1-dependent trafficking to the plasma membrane necessary for maximal cell growth.

No MeSH data available.


Related in: MedlinePlus