Biology subjects

Dambire, C.

Publications and source records attributed to Dambire, C..

3 recordsLinked to original sources

bioRxiv2026

Functional diversification of UBP6 in plant immunity through N-degron pathway regulation

Deubiquitylases are key proteolytic regulators of ubiquitin-dependent cellular processes, catalyzing the removal or remodelling of ubiquitin modifications on substrate proteins, including those targeted for proteasomal degradation. UBIQUITIN PROTEASE (UBP)6 is a deubiquitylase that promotes the abundance of NONEXPRESSOR OF PATHOGENESIS RELATED GENES (NPR)1, a conserved master regulator of plant immunity. Here, we show that the Arabidopsis thaliana protease METACASPASE (MC)9 site-specifically processes UBP6, generating the E157-UBP6 proteoform, whose stability is controlled by the Arginyl-transferase (ATE) N-degron pathway. We observed that pathogen recognition both triggers UBP6 cleavage and leads to conditional stabilisation of E157 UBP6, which is enhanced as the defence response intensifies. Our data suggest that E157 UBP6, which lacks deubiquitylating activity, may induce inhibition of the proteasome, elevating NPR1 levels and enhancing salicylic acid (SA) induced gene activation, all of which collectively contribute to restricting pathogen growth. Thus, UBP6 cleavage and N-degron pathway regulation provide distinct proteoforms of UBP6 with specific effects on the immune processes.

plant biology↗

bioRxiv2026

Conditional stability of HY5 through the ATE N-degron pathway regulates environmental responses in Arabidopsis thaliana

The N-degron pathways of ubiquitin mediated proteolysis target proteins for degradation dependent on their amino terminal residue, often produced after protease activity. Very few substrates have been identified in plants even though enzymes of these pathways are highly conserved in eukaryotes. Here we identify ELONGATED HYPOCOTYL5 (HY5), an important transcriptional regulator involved in many aspects of plant development, as a target for the endopeptidase METACASPASE (MC)9, producing the carboxy-terminal protein fragment (proteoform) E59-HY5. E59-HY5 is shown to be a substrate of the arginyl transferase (ATE) N-degron pathway, and influences physiological processes known to be controlled by HY5, including photomorphogenesis and the unfolded protein response. Conditional stability of E59-HY5 was shown to result from environmentally controlled ATE function, which may highlight a general mechanism for N-degron pathway regulation of proteoform and proteome function during growth and development.

plant biology↗

bioRxiv2022

A phloem-localized Arabidopsis metacaspase (AtMC3) improves drought tolerance

Increasing drought phenomena pose a serious threat to agricultural productivity. Although plants have multiple ways to respond to the complexity of drought stress, the underlying mechanisms of stress sensing and signalling remain unclear. The role of the vasculature, in particular the phloem, in facilitating inter-organ communication is critical. Here, we investigated the role of AtMC3, a phloem-specific member of the metacaspase family, in osmotic stress responses in Arabidopsis thaliana. Overexpression of AtMC3 conferred drought tolerance by enhancing the differentiation of the metaphloem sieve elements and maintaining higher levels of vascular-mediated transportation, whilst plants lacking the protein showed an impaired response to drought and inability to respond effectively to the hormone abscisic acid. Analyses of the proteome in plants with altered AtMC3 levels revealed differential abundance of proteins related to osmotic stress. Overall, our data highlight the importance of AtMC3 and vascular plasticity in fine-tuning early drought responses at the whole plant level without affecting growth or yield.

plant biology↗