High impact information on ROM2

• TOR2 activates this switch via ROM2, possibly via the ROM2 PH domain [1].
• Rom2p, the GDP/GTP exchange factor of Rho1p, is preferentially localized on the plasma membrane even when vesicular transport is blocked [2].
• Overexpression of Rom2p results in delocalization of Rom2p and accumulation of 1,3-beta-glucan in secretory vesicles [2].
• Rom1p and Rom2p were found to contain a DH (Dbl homologous) domain and a PH (pleckstrin homologous) domain, both of which are conserved among the GDP/GTP exchange proteins (GEPs) for the Rho family small GTP binding proteins [3].
• The glutathione-S-transferase (GST) fusion protein containing the DH domain of Rom2p showed the lipid-modified Rholp-specific GDP/GTP exchange activity which was sensitive to Rho GDP dissociation inhibitor [3].

Biological context of ROM2

• Disruption of ROM2 resulted in a temperature-sensitive growth phenotype, whereas disruption of both ROM1 and ROM2 resulted in lethality [3].
• In addition, overexpression of ROM2 could not rescue cells lacking the regulatory subunit of PKA, indicating that the Ras-adenylate, cyclase-PKA cascade is essential for Rom2p-mediated stress responses and cell growth [4].
• The effects of the deletion of ROM2 on sensitivity to hydrogen peroxide, paraquat, and cobalt ions, but not to caffeine, were reduced when a constitutive allele of RHO1 was introduced on a single copy plasmid [4].
• Rom1p and Rom2p are GDP/GTP exchange proteins (GEPs) for the Rho1p small GTP binding protein in Saccharomyces cerevisiae [3].
• Taken together, our data indicate that Rom2p can regulate PKA activity by controlling cAMP levels via the Ras-cAMP pathway and that for those stresses related to oxidative stress, this cross-talk is probably mediated via the Rho1p-activated MAPK pathway [4].

Anatomical context of ROM2

• Disruption of ROM2 results in temperature-sensitive growth defects at 11 degrees C and 37 degrees C. rom2 delta cells exhibit morphological defects [5].
• Furthermore, rom2 delta strains exhibit increased sensitivity to the microtubule depolymerizing drug benomyl [5].
• Cell wall integrity modulates RHO1 activity via the exchange factor ROM2 [6].

Associations of ROM2 with chemical compounds

• Subsequent analysis of strains with a rom2 deletion showed that Rom2p is essential for resistance to a variety of stresses caused by freeze-thawing, oxidants, cycloheximide, NaCl, or cobalt ions [4].
• The mechanism of RHO1 activation by a cell wall alteration is via the exchange factor ROM2 and could be analogous to signalling by integrin receptors in mammalian cells [6].
• Consistent with this, deletion of the ROM2 gene, which encodes a major Rho1p guanine-nucleotide exchange factor, bypassed the lethal effect of PtdIns(3)P accumulation in ymr1Delta sjl2Delta sjl3Delta triple-mutant cells [7].
• Yeast phosphatidylinositol 4-phosphate 5-kinases Mss4 and Its3 are involved in resistance against disturbance of sphingolipid biosynthesis and maintenance of cell integrity through the synthesis of PtdIns(4,5)P2 and downstream signalling through the Rom2/Rho2 and Rgf1/Rho pathways [8].

Physical interactions of ROM2

• The cytoplasmic domains of Wsc1 family members interact with the Rom2 guanine nucleotide exchange factor to stimulate GTP-binding of Rho1 [9].

Regulatory relationships of ROM2

• These results indicate that Rom1p and Rom2p are GEPs that activate Rho1p in S.cerevisiae [3].
• Stress sensitivity and the growth defect caused by the rom2 deletion could be suppressed by depleting Ras or protein kinase A (PKA) activity or by overexpressing the high affinity cAMP phosphodiesterase Pde2p [4].

Other interactions of ROM2

• ROM2 was isolated as a suppresser of heat and NaCl sensitivity caused by the lack of the Ras-GTPase activator Ira2p or of cAMP phosphodiesterases [4].
• A deletion of either ROM2 or WSC1 leads to a significant defect of 1,3-beta-glucan synthesis [10].
• This result may pose Rom2p as a mediator in the interplay between Tor1p and the Ras/cAMP pathway [11].
• Indeed, failure of Rom2 recruitment was observed in ISP-1-treated cells as well as in csg2-deleted cells, which have reduced mannosylated inositolphosphorylceramide [12].
• Pkc1 and the upstream elements of the cell integrity pathway in Saccharomyces cerevisiae, Rom2 and Mtl1, are required for cellular responses to oxidative stress [13].

References