The Prenylated Rab GTPase Receptor PRA1.F4 Contributes to Protein Exit from the Golgi Apparatus

Abstract

Prenylated Rab acceptor1 (PRA1) functions in the recruitment of prenylated Rab proteins to their cognate organelles. Arabidopsis () contains a large number of proteins belonging to the AtPRA1 family. However, their physiological roles remain largely unknown. Here, we investigated the physiological role of AtPRA1.F4, a member of the AtPRA1 family. A T-DNA insertion knockdown mutant of ,, was smaller in stature than parent plants and possessed shorter roots, whereas transgenic plants overexpressing HA:AtPRA1.F4 showed enhanced development of secondary roots and root hairs. However, both overexpression and knockdown plants exhibited increased sensitivity to high-salt stress, lower vacuolar Na/K-ATPase and plasma membrane ATPase activities, lower and higher pH in the vacuole and apoplast, respectively, and highly vesiculated Golgi apparatus. HA:AtPRA1.F4 localized to the Golgi apparatus and assembled into high-molecular-weight complexes. plants displayed a defect in vacuolar trafficking, which was complemented by low but not high levels of: Overexpression of HA:AtPRA1.F4 also inhibited protein trafficking at the Golgi apparatus, albeit differentially depending on the final destination or type of protein: trafficking of vacuolar proteins, plasma membrane proteins, and trans-Golgi network (TGN)-localized SYP61 was strongly inhibited; trafficking of TGN-localized SYP51 was slightly inhibited; and trafficking of secretory proteins and TGN-localized SYP41 was negligibly or not significantly inhibited. Based on these results, we propose that Golgi-localized AtPRA1.F4 is involved in the exit of many but not all types of post-Golgi proteins from the Golgi apparatus. Additionally, an appropriate level of AtPRA1.F4 is crucial for its function at the Golgi apparatus.

Integrative Transcriptomic and Proteomic Analyses of Molecular Mechanism Responding to Salt Stress during Seed Germination in Hulless Barley

“…The PRA1 proteins also act as receptors of Rab GTPases to regulate vesicle trafficking [74]. In Arabidopsis, both overexpression and knockdown of the PRA1.F4 gene have increased sensitivity to high salt stress and lowered vacuolar Na + /K + -ATPase and plasma membrane ATPase activities of plants [75]. Two other PRA1 proteins (HORVU3Hr1G018940.1 and HORVU1Hr1G070360.1) were down-regulated at 16 h. Thus, the functions of PRA1 proteins in response to salt stress during seed germination are complex.…”

Tomato Prenylated RAB Acceptor Protein 1 Modulates Trafficking and Degradation of the Pattern Recognition Receptor LeEIX2, Affecting the Innate Immune Response

“…Between them, AtPRA1.B6, AtPRA1.F4 and a rice ortholog from the B-type clade OsPRA1 (Os05g39670, Supplementary Figure S2 ) has been characterized as trafficking regulators that are localized in the endoplasmic reticulum (ER) or near by the ER on endosomal and Golgi compartments ( Heo et al, 2010 ; Lee M.H. et al 2011 , 2017 ). Live cell imaging confocal microscopy was used to further determine SlPRA1A subcellular localization co-expressing SlPRA1A with different endomembrane marker.…”

“…At the subcellular level, we observed a punctuate-reticular pattern of SlPRA1A in RabD2b compartments surrounding the ER in N. benthamiana and mainly in a punctuated pattern in S. lycopersicum . Interestingly, its closest Arabidopsis thaliana ortholog AtPRA1.F1 and AtPRA1.F4 also show a punctuated pattern, although in this case they are localized at Golgi compartments ( Alvim Kamei et al, 2008 ; Lee et al, 2017 ). Remarkably, the size of the RabD2b compartments is altered by SlPRA1A, suggesting that SlPRA1A functions in these compartments.…”

“…Recently, AtPRA1.F4 has been described as a Golgi membrane protein that regulates the trafficking of plasma membrane and vacuolar proteins ( Lee et al, 2017 ). AtPRA1F4 overexpression inhibits the trafficking of plasma membrane and vacuolar proteins to their target compartment.…”

Di-arginine and FFAT-like motifs retain a subpopulation of PRA1 at ER-mitochondria membrane contact sites

“…In fact, knock-out of the PRA1 homolog in yeast demonstrates that it is non-essential, with no evident phenotype in the endosomal system and no change in Rab GTPase localization (Cabrera and Ungermann, 2013; Geng et al, 2005). Furthermore, in-vivo evidence points to a more structural role within the early secretory pathway as knock-down or knock-out of PRA1 leads to abnormal ER and Golgi phenotypes (Geng et al, 2005; Lee et al, 2017; Liu et al, 2011; Simpson et al, 2012). We recently used an unbiased approach that takes into account the membrane association of PRA1 to screen for novel binding partners and failed to identify any Rab GTPases (Abu Irqeba and Ogilvie, 2019).…”