Adaptation to Fe-deficiency requires remodeling of the photosynthetic apparatus.
The molecular mechanisms underlying the onset of Fe-deficiency chlorosis and the maintenance of photosynthetic function in chlorotic chloroplasts are relevant to global photosynthetic productivity. We describe a series of graded responses of the photosynthetic apparatus to Fe-deficiency, including a novel response that occurs prior to the onset of chlorosis, namely the disconnection of the LHCI antenna from photosystem I (PSI). We propose that disconnection is mediated by a change in the physical properties of PSI-K in PSI in response to a change in plastid Fe content, which is sensed through the occupancy, and hence activity, of the Fe-containing active site in Crd1. We show further that progression of the response involves remodeling of the antenna complexes-specific degradation of existing proteins coupled to the synthesis of new ones, and establishment of a new steady state with decreased stoichiometry of electron transfer complexes. We suggest that these responses are typical of a dynamic photosynthetic apparatus where photosynthetic function is optimized and photooxidative damage is minimized in graduated responses to a combination of nutrients, light quantity and quality.
Moseley
Jeffrey L
JL
Department of Chemistry and Biochemistry, UCLA, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569, USA.
Allinger
Tanja
T
Herzog
Sebastian
S
Hoerth
Patric
P
Wehinger
Elke
E
Merchant
Sabeeha
S
Hippler
Michael
M
D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000378:metabolism* / Q000502:physiology*; D002713:Chlorine / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015180:Electrophoresis, Gel, Two-Dimensional; D005786:Gene Expression Regulation; D015151:Immunoblotting; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D013058:Mass Spectrometry; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018087:Plastids / Q000378:metabolism; D020543:Proteome; D012313:RNA / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013997:Time Factors
D045342:Light-Harvesting Protein Complexes; D010455:Peptides; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D020543:Proteome; C438010:PsaK protein, barley; D002734:Chlorophyll; D002713:Chlorine; D012313:RNA; D007501:Iron