Although photoheterotrophic iron-limited cells can generate a thylakoid lumen pH low enough to induce the xanthophyll cycle, it is possible that the buy 10058-F4 decreased capacity

for photosynthetic electron transport in these cells is PF-01367338 ic50 unable to maintain a lumen pH that is low enough to induce NPQ to the same extent as in phototrophic cells. This result could also indicate that LhcSR proteins are required for functions other than NPQ. We noted that the plastoquinone pool of iron-limited photoheterotrophic cells was more reduced, even in the dark (Fig. 6). The reduction of plastoquinone is known to occur in Chlamydomonas by chlororespiration via a nucleus-encoded type-II NAD(P)H dehydrogenase (Mus et al. 2005; Jans et al. 2008; Desplats et al. 2009). In the light, one possibility is that the observed reduction of the plastoquinone pool in iron-limited photoheterotrophic cells is due in part to a reduced number of PSI centers Alvocidib manufacturer in iron-limited cells (Moseley et al. 2002). In conclusion, in the presence of acetate, iron-limited Chlamydomonas cells maintain high growth rates by suppressing photosynthesis and prioritizing respiration, while phototrophic cells maintain efficient photosynthetic

systems throughout the spectrum of iron status, but still lose overall photosynthetic capacity at the onset of iron deficiency, which is delayed in phototrophic cells (0.1-μM Fe vs. 1-μM Fe in photoheterotrophic cells) due to their increased iron content. Acknowledgments We thank Patrice Hamel for antibodies against Nuo6-8, Susanne Preiss for antibodies against D1, Michel Guertin for antibodies against LhcSR, and Jean-David Rochaix for antibodies against PsaD. We are grateful to Janette Kropat for the measurement of iron shown Ibrutinib purchase in Fig. 2 and to Marina Sharifi for assistance with HPLC analysis, to Davin Malasarn for his assistance with Visual Minteq and to Naomi Ginsberg for extrapolating the data shown in Table 3 using Matlab. This research was supported by grants from the Department of Energy (DE-FD02-04ER15529)

to S.S.M. and from the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (FWP number 449A449B) to K.K.N. Aimee Terauchi was supported by an Institutional Ruth L. Kirschstein National Research Service Award (GM070104) and a Dissertation Year Fellowship from the UCLA graduate division. Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. Electronic supplementary material Below is the link to the electronic supplementary material.