title: Upregulation of PG synthesis on sulfur-starvation for PS I in Chlamydomonas.
abstract: Sulfur(S)-starvation was previously shown to induce the degradation of an acidic lipid in chloroplasts, sulfoquinovosyl diacylglycerol (SQDG), to yield a major internal S-source in a green alga, Chlamydomonas reinhardtii. We here found that the synthesis of phosphatidylglycerol (PG), the other acidic lipid in chloroplasts, is activated to elevate its content up to a level that just compensates for the loss of SQDG. Similar activation of PG synthesis was also observed in an SQDG-deficient mutant under S-replete conditions, which led us to propose that upregulation of PG synthesis under S-starved conditions occurs through direct sensing of SQDG-loss, but not of S-starvation. Moreover, thylakoid membranes isolated from S-starved cells were reduced in photosystem I activity on treatment with phospholipase A(2) that specifically broke down PG, which suggested a critical role of PG that is increased under S-starved conditions in the maintenance of the photosystem I activity.
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi 1432-1, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Takafumi
authors.initials: T
authors.lastname: Midorikawa
authors.forename: Mikio
authors.initials: M
authors.lastname: Tsuzuki
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sato
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000187:drug effects / Q000378:metabolism*; D010715:Phosphatidylglycerols / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000187:drug effects / Q000378:metabolism*; D013455:Sulfur / Q000008:administration & dosage*; D020524:Thylakoids / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D010715:Phosphatidylglycerols; D045331:Photosystem I Protein Complex; D013455:Sulfur