RRC ID 48576
著者 Hauenstein M, Christ B, Das A, Aubry S, Hörtensteiner S.
タイトル A Role for TIC55 as a Hydroxylase of Phyllobilins, the Products of Chlorophyll Breakdown during Plant Senescence.
ジャーナル Plant Cell
Abstract Chlorophyll degradation is the most obvious hallmark of leaf senescence. Phyllobilins, linear tetrapyrroles that are derived from opening of the chlorin macrocycle by the Rieske-type oxygenase PHEOPHORBIDE a OXYGENASE (PAO), are the end products of chlorophyll degradation. Phyllobilins carry defined modifications at several peripheral positions within the tetrapyrrole backbone. While most of these modifications are species-specific, hydroxylation at the C32 position is commonly found in all species analyzed to date. We demonstrate that this hydroxylation occurs in senescent chloroplasts of Arabidopsis thaliana. Using bell pepper (Capsicum annuum) chromoplasts, we establish that phyllobilin hydroxylation is catalyzed by a membrane-bound, molecular oxygen-dependent, and ferredoxin-dependent activity. As these features resemble the requirements of PAO, we considered membrane-bound Rieske-type oxygenases as potential candidates. Analysis of mutants of the two Arabidopsis Rieske-type oxygenases (besides PAO) uncovered that phyllobilin hydroxylation depends on TRANSLOCON AT THE INNER CHLOROPLAST ENVELOPE55 (TIC55). Our work demonstrates a catalytic activity for TIC55, which in the past has been considered as a redox sensor of protein import into plastids. Given the wide evolutionary distribution of both PAO and TIC55, we consider that chlorophyll degradation likely coevolved with land plants.
巻・号 28(10)
ページ 2510-2527
公開日 2016-10-1
DOI 10.1105/tpc.16.00630
PII tpc.16.00630
PMID 27655840
PMC PMC5134989
MeSH Aging / genetics Aging / physiology Arabidopsis / genetics Arabidopsis / metabolism* Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Chlorophyll / metabolism
IF 9.618
引用数 38
WOS 分野 PLANT SCIENCES BIOCHEMISTRY & MOLECULAR BIOLOGY CELL BIOLOGY
リソース情報
シロイヌナズナ / 植物培養細胞・遺伝子 pda06002