ARC1 Is an E3 Ubiquitin Ligase and Promotes the Ubiquitination of Proteins during the Rejection of Self-Incompatible Brassica Pollen

AUTOR(ES)

Stone, Sophia L.

FONTE

American Society of Plant Biologists

RESUMO

ARC1 is a novel U-box protein required in the Brassica pistil for the rejection of self-incompatible pollen; it functions downstream of the S receptor kinase (SRK). Here, we show that ARC1 has E3 ubiquitin ligase activity and contains several motifs that influence its subcellular localization. ARC1 can shuttle between the nucleus, cytosol, and proteasome/COP9 signalosome (CSN) when expressed in tobacco BY-2 suspension-cultured cells. However, ARC1 localization to the proteasome/CSN occurs only in the presence of an active SRK. In the pistil, ubiquitinated protein levels increase specifically with incompatible pollinations, but they do not change in ARC1 antisense-suppressed pistils. In addition, inhibition of the proteasomal proteolytic activity disrupts the self-incompatibility response. We propose that ARC1 promotes the ubiquitination and proteasomal degradation of compatibility factors in the pistil, which in turn leads to pollen rejection.

Documentos Relacionados

• S RNase and Interspecific Pollen Rejection in the Genus Nicotiana: Multiple Pollen-Rejection Pathways Contribute to Unilateral Incompatibility between Self-Incompatible and Self-Compatible Species.
• Molecular characterization of the S locus in two self-incompatible Brassica napus lines.
• Structural and transcriptional comparative analysis of the S locus regions in two self-incompatible Brassica napus lines.
• Cellular Pathways Regulating Responses to Compatible and Self-Incompatible Pollen in Brassica and Arabidopsis Stigmas Intersect at Exo70A1, a Putative Component of the Exocyst Complex[W]
• The RAG1 N-terminal domain is an E3 ubiquitin ligase