%0 Journal Article
%T Evidence That Putrescine Modulates the Higher Plant Photosynthetic Proton Circuit
%A Nikolaos E. Ioannidis
%A Jeffrey A. Cruz
%A Kiriakos Kotzabasis
%A David M. Kramer
%J PLOS ONE
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0029864
%X The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf), comprised of electrical (¦¤¦×) and osmotic (¦¤pH) components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ¦¤pH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the qE mechanism, and governing electron transfer at the cytochrome b6f complex. Differential partitioning of pmf into ¦¤pH and ¦¤¦× has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type) and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029864