Uracil phosphoribosyltransferase is required to establish a functional cytochrome b6/f complex

ABSTRACT: Arabidopsis uracil phosphoribosyltransferase (UPP) is an essential enzyme and plants lacking this enzyme are strongly compromised in chloroplast function. Our analysis of UPP amiRNA mutants has confirmed that this vital function is crucial to establish a fully functional photosynthesis as the RIESKE iron sulfur protein (PetC) is almost absent, leading to a block in photosynthetic electron transport. Interestingly, this function appears to be unrelated to nucleotide homeostasis since nucleotide levels were not altered in the studied mutants. Transcriptomics and proteomic analysis showed that protein homeostasis but not gene expression is most likely responsible for this observation and high light (HL) provoked an upregulation of protease levels, including thylakoid filamentation temperature-sensitive 1, 5 (FtsH), caseinolytic protease proteolytic subunit 1 (ClpP1), and processing peptidases, as well as components of the chloroplast protein import machinery in UPP amiRNA lines. Strongly reduced PetC amounts were not only detected by immunoblot from mature plants but in addition in de-etiolation experiment with young seedlings and are causing reduced high light-induced non-photochemical quenching (NPQ) but increased unregulated energy dissipation (NO). Our work suggests that UPP assists in stabilization PetC during the assembly of the Fe-S cluster and targeting to the thylakoid or protects it against proteolytic degradation.

INSTRUMENT(S): impact HD

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Plant Cell

SUBMITTER: Serena Schwenkert  

LAB HEAD: Serena Schwenkert

PROVIDER: PXD052789 | Pride | 2024-12-09

REPOSITORIES: Pride