Heterotrimeric guanine nucleotide-binding proteins (G-proteins) containing alpha, beta and gamma subunits are an important signaling switches conserved in all eukaryotes. Our group is interested in: 1) identification of new members in G-protein signaling pathway; 2) molecular mechanism of G-protein-regulated chloroplast development; 3) identification of nuclear encoded genes controlling chloroplast development.

Principal Investigator: Dr. Ji-Rong Huang, Professor. Email: huangjr@sibs.ac.cn
Staff: Dr. Lin-Gang Zhang, Research Associate; Dr. Mu-Lan Zhu, Wei-Hua Huang, Guang-Zhen Hu, Wen-Bin Zhou, Research Assistants; Hong Li, Technician; Jia-Mian Wei, Professor (emeritus)
Postdoctoral Fellow: Dr. Yu-Xiang Cheng; Dr. Nabil Ibrahim El sheery
Graduate Students: Wen-Juan Wu; Ying Zhu; Yi Sun; Qing-Bo Chen; Ya-Juan Zhu
Graduated Students: Qing Wei, 2002 (PhD); Guang-Zhen Hu, 2005 (PhD); Wen-Bin Zhou, 2005 (PhD)

The Arabidopsis Gene YS1 Encoding a DYW Protein is Required for Editing of rpoB Transcripts and the Rapid Development of Chloroplasts During Early Growth
Virescence, a phenotype in which leaves green more slowly than usual, is recognized to play a role in protection from photo-oxidative damage before healthy chloroplasts are developed. The elucidation of the molecular mechanisms underlying virescence will provide insights into how the development of chloroplasts is controlled. In this study, we find that knockout alleles of Yellow Seedlings 1 (YS1) in Arabidopsis leads to a virescent phenotype, which disappears by 3 weeks after germination. The ys1 mutation resulted in marked decreases in photosynthetic capacity and photosynthetic pigment complexes, and disturbed ultrastructure of thylakoid membranes in 8-day-old seedlings. However, cotyledons of ys1 seedlings pretreated with darkness for 5 days turn green almost as fast as the wild type in light, revealing that the developmental defects in ys1 are limited to the first few days after germination. Inspection of all known plastid RNA editing and splicing events revealed that YS1 is absolutely required for editing of site 25992 in rpoB transcripts encoding the beta subunit of the plastid-encoded RNA polymerase (PEP). YS1 is a nuclear-encoded chloroplast-localized pentatricopeptide repeat protein but differs from previously described editing factors in that it has a C-terminal DYW motif. A defect in PEP activity is consistent with the changes in plastid transcript patterns observed in ys1 seedlings. We conclude that the activity of PEP containing RpoB translated from unedited transcripts is insufficient to support rapid chloroplast differentiation.

主要论文：

1. Zhou WB, Cheng YX, Yap A, Chateigner-Boutin AL, Delannoy E, Hammani K, Small I, Huang JR. (2008) The Arabidopsis gene YS1 encoding a DYW protein is required for editing of rpoB transcripts and the rapid development of chloroplasts during early growth. Plant Journal (10.1111/j.1365-313X.2008.03766.x)

2. Zhang LG, Hu GZ, Cheng YX, and Huang JR. (2008) Heterotrimeric G Protein α and β Subunits Antagonistically Modulate Stomatal Number in Arabidopsis thaliana. Developmental Biology 324: 68-75.

3. Wei Q, Zhou WB, Hu GZ, Wei JM, Yang HQ and Huang JR. (2008) Heterotrimeric G-protein Mediates Far-Red Preconditioned Cell Death of Hypocotyls in Arabidopsis thaliana. Cell Research 18: 949-960.

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