Circadian clock-related transcription factors Reveille 1 and Reveille 8 regulate the O -acetylserine cluster genes and sulfur homeostasis

Jun 14, 2026Plant physiology

Daily rhythm proteins Reveille 1 and 8 control sulfur-related genes and balance in plants

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Abstract

O-acetylserine (OAS) accumulation is regulated by multiple serine acetyltransferase isoforms and transcription factors.

No single SERAT isoform is solely responsible for the full induction of OAS cluster genes.
Loss of any of the three major SERAT isoforms reduces gene induction, with SERAT2;2 having a predominant role.
Three transcription factors, SLIM1, RVE1, and RVE8, are required for the regulation of OAS cluster genes.
These transcription factors bind to the promoters of OAS cluster genes and also influence OAS accumulation.
RVE1 and RVE8 contribute to responses related to sulfur deficiency at both transcriptional and metabolic levels.

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O-acetylserine (OAS) is the sulfur acceptor in primary sulfate assimilation and the precursor of cysteine, synthesized by serine acetyltransferase (SERAT). Beyond its metabolic role, OAS acts as a signaling molecule, accumulating during sulfur starvation and inducing sulfur-deficiency marker genes. Recently, OAS was also shown to increase transiently after a light-dark transition, triggering the induction of a group of "OAS cluster" genes. Here, we investigated the mechanisms underlying OAS accumulation and the regulation of OAS cluster genes. We found that no single SERAT isoform accounts for the full induction of OAS cluster genes; instead, the loss of any of the three major isoforms (SERAT1;1, SERAT2;1, SERAT2;2) reduced induction, with SERAT2;2 playing a predominant role. All five isoforms contributed to the response to varying degrees. In addition, three transcription factors were required: the sulfur-deficiency regulator SLIM1 and the circadian clock components RVE1 and RVE8. These factors bound to OAS cluster gene promoters and unexpectedly controlled OAS accumulation itself. While RVE1 and RVE8 did not transduce the OAS signal, they contributed to sulfur-deficiency responses at both the transcriptional and metabolic levels. Together, our findings reveal a complex regulatory network involving multiple SERAT isoforms and transcription factors, advancing our understanding of sulfur homeostasis and its integration with light and circadian regulation.

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Circadian clock-related transcription factors Reveille 1 and Reveille 8 regulate the O -acetylserine cluster genes and sulfur homeostasis

Abstract

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