Journal article

Nt-RhoGDI2 regulates Rac/Rop signaling and polar cell growth in tobacco pollen tubes

Publication Details
Author(s): Klahre U, Becker C, Schmitt A, Kost B
Journal: Plant Journal
Publisher: Wiley-Blackwell
Publication year: 2006
Volume: 46
Journal issue: 6
Pages range: 1018-1031
ISSN: 0960-7412


Rac/Rop-type Rho-family small GTPases accumulate at the plasma membrane in the tip of pollen tubes and control the polar growth of these cells. Nt-RhoGDI2, a homolog of guanine nucleotide dissociation inhibitors (GDIs) regulating Rho signaling in animals and yeast, is co-expressed with the Rac/Rop GTPase Nt-Rac5 specifically in tobacco (Nicotiana tabacum) pollen tubes. The two proteins interact with each other in yeast two-hybrid assays, preferentially when Nt-Rac5 is prenylated. Transient over-expression of Nt-Rac5 and Nt-RhoGDI2 depolarized or inhibited tobacco pollen tube growth, respectively. Interestingly, pollen tubes over-expressing both proteins grew normally, demonstrating that the two proteins functionally interact in vivo. Nt-RhoGDI2 was localized to the pollen tube cytoplasm and effectively transferred co-over-expressed YFP-Nt-Rac5 fusion proteins from the plasma membrane to this compartment. A single amino acid exchange (R69A), which abolished binding to Nt-RhoGDI2, caused Nt-Rac5 to be mis-localized to the flanks of pollen tubes and strongly compromised its ability to depolarize pollen tube growth upon over-expression. Based on these observations, we propose that Nt-RhoGDI2-mediated recycling of Nt-Rac5 from the flanks of the tip to the apex has an essential function in the maintenance of polarized Rac/Rop signaling and cell expansion in pollen tubes. Similar mechanisms may generally play a role in the polarized accumulation of Rho GTPases in specific membrane domains, an important process whose regulation has not been well characterized in any cell type to date.

How to cite
APA: Klahre, U., Becker, C., Schmitt, A., & Kost, B. (2006). Nt-RhoGDI2 regulates Rac/Rop signaling and polar cell growth in tobacco pollen tubes. Plant Journal, 46(6), 1018-1031.

MLA: Klahre, Ulrich, et al. "Nt-RhoGDI2 regulates Rac/Rop signaling and polar cell growth in tobacco pollen tubes." Plant Journal 46.6 (2006): 1018-1031.

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