Ubiquitin–proteasome‐mediated degradation of S‐RNase in a solanaceous cross‐compatibility reaction. (21st May 2014)

• Record Type: Journal Article
• Authors: Entani, Tetsuyuki; Kubo, Ken‐ichi; Isogai, Shin; Fukao, Yoichiro; Shirakawa, Masahiro; Isogai, Akira; Takayama, Seiji
• Is Part Of: Plant journal. Volume 78:Number 6(2014:Jun.)
• Page Start: 1014
• Page End: 1021
• Publication Date: 2014-05-21
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12528
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12528-abs-0001"> <title>Summary</title> <p>Many plants have a self‐incompatibility (SI) system in which the rejection of self‐pollen is determined by multiple haplotypes at a single locus, termed <italic>S</italic>. In the Solanaceae, each haplotype encodes a single ribonuclease (S‐RNase) and multiple <italic>S</italic>‐locus F‐box proteins (SLFs), which function as the pistil and pollen SI determinants, respectively. S‐RNase is cytotoxic to self‐pollen, whereas SLFs are thought to collaboratively recognize non‐self S‐RNases in cross‐pollen and detoxify them via the ubiquitination pathway. However, the actual mechanism of detoxification remains unknown. Here we isolate the components of a SCF^SLF (SCF = SKP1‐CUL1‐F‐box‐RBX1) from <italic>Petunia</italic> pollen. The SCF^SLF polyubiquitinates a subset of non‐self S‐RNases <italic>in vitro</italic>. The polyubiquitinated S‐RNases are degraded in the pollen extract, which is attenuated by a proteasome inhibitor. Our findings suggest that multiple SCF^SLF complexes in cross‐pollen polyubiquitinate non‐self S‐RNases, resulting in their degradation by the proteasome.</p> </abstract>