title: Connectivity between electron transport complexes and modulation of photosystem II activity in chloroplasts.
abstract: In chloroplasts, photosynthetic electron transport complexes interact with each other via the mobile electron carriers (plastoquinone and plastocyanin) which are in surplus amounts with respect to photosystem I and photosystem II (PSI and PSII), and the cytochrome b6f complex. In this work, we analyze experimental data on the light-induced redox transients of photoreaction center P700in chloroplasts within the framework of our mathematical model. This analysis suggests that during the action of a strong actinic light, even significant attenuation of PSII [for instance, in the result of inhibition of a part of PSII complexes by DCMU or due to non-photochemical quenching (NPQ)] will not cause drastic shortage of electron flow through PSI. This can be explained by "electronic" and/or "excitonic" connectivity between different PSII units. At strong AL, the overall flux of electrons between PSII and PSI will maintain at a high level even with the attenuation of PSII activity, provided the rate-limiting step of electron transfer is beyond the stage of PQH2formation. Results of our study are briefly discussed in the context of NPQ-dependent mechanism of chloroplast protection against light stress.
authors.affiliation: Faculty of Physics, Moscow State University, Moscow, Russia, 119991. an_tikhonov@mail.ru.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Tikhonov
authors.affiliation: Faculty of Physics, Moscow State University, Moscow, Russia, 119991.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Vershubskii
mesh_terms: D001692:Biological Transport / Q000528:radiation effects; D002736:Chloroplasts / Q000378:metabolism* / Q000528:radiation effects; D004579:Electron Transport / Q000528:radiation effects; D007887:Fabaceae / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D010084:Oxidation-Reduction / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D011522:Protons; D013997:Time Factors
chemical_list: D045332:Photosystem II Protein Complex; D011522:Protons
keywords: Chloroplasts; Electron transport; Interaction of electron transport complexes; Mathematical modeling; Proton potential