A Functional Component of the Transcriptionally Active Chromosome Complex, Arabidopsis pTAC14, Interacts with pTAC12/HEMERA and Regulates Plastid Gene Expression

Zhi-Ping Gao,Qing-Bo Yu,Tuan-Tuan Zhao,Guo-Xiang Chen,Zhong-Nan Yang,Qian Ma

doi:10.1104/pp.111.184762

Zhi-Ping Gao, Qing-Bo Yu + Show 4 more

Open Access

https://doi.org/10.1104/pp.111.184762

Copy DOI

Journal: Plant Physiology	Publication Date: Oct 18, 2011
Citations: 91	License type: CC BY 4.0

Affiliation: Nanjing Normal University

Abstract

The SET domain-containing protein, pTAC14, was previously identified as a component of the transcriptionally active chromosome (TAC) complexes. Here, we investigated the function of pTAC14 in the regulation of plastid-encoded bacterial-type RNA polymerase (PEP) activity and chloroplast development. The knockout of pTAC14 led to the blockage of thylakoid formation in Arabidopsis (Arabidopsis thaliana), and ptac14 was seedling lethal. Sequence and transcriptional analysis showed that pTAC14 encodes a specific protein in plants that is located in the chloroplast associated with the thylakoid and that its expression depends on light. In addition, the transcript levels of all investigated PEP-dependent genes were clearly reduced in the ptac14-1 mutants, while the accumulation of nucleus-encoded phage-type RNA polymerase-dependent transcripts was increased, indicating an important role of pTAC14 in maintaining PEP activity. pTAC14 was found to interact with pTAC12/HEMERA, another component of TACs that is involved in phytochrome signaling. The data suggest that pTAC14 is essential for proper chloroplast development, most likely by affecting PEP activity and regulating PEP-dependent plastid gene transcription in Arabidopsis together with pTAC12.

Highlights

The SET domain-containing protein, pTAC14, was previously identified as a component of the transcriptionally active chromosome (TAC) complexes
plastid-encoded bacterialtype RNA polymerase (PEP)-dependent chloroplast genes were clearly decreased in the knockout lines, suggesting that PEP activity was deficient in ptac14
PTAC14, a Thylakoid-Associated Protein, Is Essential for Chloroplast Development pTAC14 was originally identified from chloroplasts as one component of TACs by gel filtration and affinity chromatography purification (Pfalz et al, 2006), but its molecular function remains unclear to date

Summary

Introduction

The SET domain-containing protein, pTAC14, was previously identified as a component of the transcriptionally active chromosome (TAC) complexes. Studies indicate that SET domain proteins are involved in chromatin structure, gene silencing, transcriptional activation, plant metabolism, and other processes (Trievel et al, 2002; Yu et al, 2009b; Liu et al, 2010). Studies on these SET domain proteins are still limited, and the biological functions of a large number of SET domain-containing proteins in chloroplast development remain a mystery. These data suggest that pTAC14, a functional component of the TACs, regulates chloroplast gene expression and chloroplast development by interacting with pTAC12 in Arabidopsis

Methods

Results

Conclusion