Ubiquitin Lysine 63 Chain–Forming Ligases Regulate Apical Dominance inArabidopsis

Abstract

Lys-63-linked multiubiquitin chains play important roles in signal transduction in yeast and in mammals, but the functions for this type of chain in plants remain to be defined. The RING domain protein RGLG2 (for RING domain Ligase2) from Arabidopsis thaliana can be N-terminally myristoylated and localizes to the plasma membrane. It can form Lys-63-linked multiubiquitin chains in an in vitro reaction. RGLG2 has overlapping functions with its closest sequelog, RGLG1, and single mutants in either gene are inconspicuous. rglg1 rglg2 double mutant plants exhibit loss of apical dominance and altered phyllotaxy, two traits critically influenced by the plant hormone auxin. Auxin and cytokinin levels are changed, and the plants show a decreased response to exogenously added auxin. Changes in the abundance of PIN family auxin transport proteins and synthetic lethality with a mutation in the auxin transport regulator BIG suggest that the directional flow of auxin is modulated by RGLG activity. Modification of proteins by Lys-63-linked multiubiquitin chains is thus important for hormoneregulated, basic plant architecture.

Arabidopsis Defense against Botrytis cinerea: Chronology and Regulation Deciphered by High-Resolution Temporal Transcriptomic Analysis

“…This group of genes includes anthranilate synthase (ASA1), a rate-limiting step in the synthesis of the auxin precursor Trp, STY1, a transcriptional activator of auxin biosynthesis (Eklund et al, 2010), and two paralogous genes (RGLG1 and 2) thought to be responsible for directional flow of auxin (Yin et al, 2007). At least in roots, ASA1 and ASB1 are required for ET-mediated increases in auxin (Stepanova et al, 2005).…”

Transcriptional control of flavonoid biosynthesis

“…12 These developmental abnormalities are reminiscent of auxindeficient or -insensitive mutants. [48][49][50] Microarray analysis of mTCP3 seedlings reveals many auxin-related genes with reduced expression levels, including the early auxin-responsive genes (GH3.17 and AUX/IAA29), the auxin transporter protein genes (PGP19, PGP1, and AUX1) and the auxin receptor gene TIR1. 12 Contrarily, enhanced expression of several auxin-related genes (AUX/ IAA29, PAR1, and PGP1) is detectable in TCP3SRDX plants.…”

Lysine 63 -linked ubiquitylation of PIN2 auxin carrier protein governs hormonally controlled adaptation of Arabidopsis root growth

“…Next, we analyzed PIN2 ubiquitylation in the Arabidopsis rglg1 rglg2 double mutant, which is deficient in RING-finger E3 ligases demonstrated to catalyze ubK63 chain formation in vitro (20). We found a reduction in the amounts of ubK63 chain-specific signals in PIN2-IPs, suggesting that RGLG proteins make an important contribution to PIN2 ubiquitylation in planta (Fig.…”