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OsGAP1 functions as a positive regulator of OsRab11-mediated TGN to PM or vacuole trafficking.
Plant Cell Physiol. 2005 Dec; 46(12):2005-18.PC

Abstract

The Ypt/Rab family of small G-proteins is important in regulating vesicular transport. Rabs hydrolyze GTP very slowly on their own and require GTPase-activating proteins (GAPs). Here we report the identification and characterization of OsGAP1, a Rab-specific rice GAP. OsGAP1 strongly stimulated OsRab8a and OsRab11, which are homologs of the mammalian Rab8 and Rab11 proteins that are essential for Golgi to plasma membrane (PM) and trans-Golgi network (TGN) to PM trafficking, respectively. Substitution of two invariant arginines within the catalytic domain of Oryza sativa GTPase-activating protein 1 (OsGAP1) with alanines significantly inhibited its GAP activity. In vivo targeting experiments revealed that OsGAP1 localizes to the TGN or pre-vacuolar compartment (PVC). A yeast expression system demonstrated that wild-type OsGAP1 facilitates O. sativa dissociation inhibitor 3 (OsGDI3)-catalyzed OsRab11 recycling at an early stage, but the OsGAP1(R385A) and (R450A) mutants do not. Thus, GTP hydrolysis is essential for Rab recycling. Moreover, expression of the OsGAP1 mutants in Arabidopsis protoplasts inhibited the trafficking of some cargo proteins, including the PM-localizing H+-ATPase-green fluorescent protein (GFP) and Ca2+-ATPase8-GFP and the central vacuole-localizing Arabidopsis aleurain-like protein (AALP)-GFP. The OsGAP1 mutants caused these proteins to accumulate at the Golgi apparatus. Surprisingly, OsRab11 overproduction relieved the inhibitory effect of the OsGAP1 mutants on vesicular trafficking. OsRab8a had no such effect. Thus, the OsGAP1 mutants may inhibit TGN to PM or central vacuole trafficking because they induce the sequestration of endogenous Rab11. We propose that OsGAP1 facilitates vesicular trafficking from the TGN to the PM or central vacuole by both stimulating the GTPase activity of OsRab11 and increasing the recycling of inactive OsRab11.

Authors+Show Affiliations

Division of Applied Life Sciences, Graduate School of Gyeongsang National University, Jinju 660-701, Korea.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16230331

Citation

Heo, Jae Bok, et al. "OsGAP1 Functions as a Positive Regulator of OsRab11-mediated TGN to PM or Vacuole Trafficking." Plant & Cell Physiology, vol. 46, no. 12, 2005, pp. 2005-18.
Heo JB, Rho HS, Kim SW, et al. OsGAP1 functions as a positive regulator of OsRab11-mediated TGN to PM or vacuole trafficking. Plant Cell Physiol. 2005;46(12):2005-18.
Heo, J. B., Rho, H. S., Kim, S. W., Hwang, S. M., Kwon, H. J., Nahm, M. Y., Bang, W. Y., & Bahk, J. D. (2005). OsGAP1 functions as a positive regulator of OsRab11-mediated TGN to PM or vacuole trafficking. Plant & Cell Physiology, 46(12), 2005-18.
Heo JB, et al. OsGAP1 Functions as a Positive Regulator of OsRab11-mediated TGN to PM or Vacuole Trafficking. Plant Cell Physiol. 2005;46(12):2005-18. PubMed PMID: 16230331.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - OsGAP1 functions as a positive regulator of OsRab11-mediated TGN to PM or vacuole trafficking. AU - Heo,Jae Bok, AU - Rho,Hee Sun, AU - Kim,Se Won, AU - Hwang,Sung Min, AU - Kwon,Hyun Jin, AU - Nahm,Min Yeop, AU - Bang,Woo Young, AU - Bahk,Jeong Dong, Y1 - 2005/10/17/ PY - 2005/10/19/pubmed PY - 2006/3/1/medline PY - 2005/10/19/entrez SP - 2005 EP - 18 JF - Plant & cell physiology JO - Plant Cell Physiol VL - 46 IS - 12 N2 - The Ypt/Rab family of small G-proteins is important in regulating vesicular transport. Rabs hydrolyze GTP very slowly on their own and require GTPase-activating proteins (GAPs). Here we report the identification and characterization of OsGAP1, a Rab-specific rice GAP. OsGAP1 strongly stimulated OsRab8a and OsRab11, which are homologs of the mammalian Rab8 and Rab11 proteins that are essential for Golgi to plasma membrane (PM) and trans-Golgi network (TGN) to PM trafficking, respectively. Substitution of two invariant arginines within the catalytic domain of Oryza sativa GTPase-activating protein 1 (OsGAP1) with alanines significantly inhibited its GAP activity. In vivo targeting experiments revealed that OsGAP1 localizes to the TGN or pre-vacuolar compartment (PVC). A yeast expression system demonstrated that wild-type OsGAP1 facilitates O. sativa dissociation inhibitor 3 (OsGDI3)-catalyzed OsRab11 recycling at an early stage, but the OsGAP1(R385A) and (R450A) mutants do not. Thus, GTP hydrolysis is essential for Rab recycling. Moreover, expression of the OsGAP1 mutants in Arabidopsis protoplasts inhibited the trafficking of some cargo proteins, including the PM-localizing H+-ATPase-green fluorescent protein (GFP) and Ca2+-ATPase8-GFP and the central vacuole-localizing Arabidopsis aleurain-like protein (AALP)-GFP. The OsGAP1 mutants caused these proteins to accumulate at the Golgi apparatus. Surprisingly, OsRab11 overproduction relieved the inhibitory effect of the OsGAP1 mutants on vesicular trafficking. OsRab8a had no such effect. Thus, the OsGAP1 mutants may inhibit TGN to PM or central vacuole trafficking because they induce the sequestration of endogenous Rab11. We propose that OsGAP1 facilitates vesicular trafficking from the TGN to the PM or central vacuole by both stimulating the GTPase activity of OsRab11 and increasing the recycling of inactive OsRab11. SN - 0032-0781 UR - https://www.unboundmedicine.com/medline/citation/16230331/OsGAP1_functions_as_a_positive_regulator_of_OsRab11_mediated_TGN_to_PM_or_vacuole_trafficking_ L2 - https://academic.oup.com/pcp/article-lookup/doi/10.1093/pcp/pci215 DB - PRIME DP - Unbound Medicine ER -