Psencík Jakub, Arellano Juan B, Ikonen Teemu P, Borrego Carles M, Laurinmäki Pasi A, Butcher Sarah J, Serimaa Ritva E, Tuma Roman
Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic.
Biophys J. 2006 Aug 15;91(4):1433-40. doi: 10.1529/biophysj.106.084228. Epub 2006 May 26.
Chlorosomes are the main light harvesting complexes of green photosynthetic bacteria. Recently, a lamellar model was proposed for the arrangement of pigment aggregates in Chlorobium tepidum chlorosomes, which contain bacteriochlorophyll (BChl) c as the main pigment. Here we demonstrate that the lamellar organization is also found in chlorosomes from two brown-colored species (Chl. phaeovibrioides and Chl. phaeobacteroides) containing BChl e as the main pigment. This suggests that the lamellar model is universal among green sulfur bacteria. In contrast to green-colored Chl. tepidum, chlorosomes from the brown-colored species often contain domains of lamellar aggregates that may help them to survive in extremely low light conditions. We suggest that carotenoids are localized between the lamellar planes and drive lamellar assembly by augmenting hydrophobic interactions. A model for chlorosome assembly, which accounts for the role of carotenoids and secondary BChl homologs, is presented.
叶绿体是绿色光合细菌主要的光捕获复合体。最近，有人提出了一种片层模型，用于描述嗜热绿菌叶绿体中色素聚集体的排列方式，该叶绿体以细菌叶绿素（BChl）c作为主要色素。在此，我们证明，在以BChl e作为主要色素的两种棕色菌（褐弯菌属和褐杆菌属）的叶绿体中也发现了片层结构。这表明片层模型在绿色硫细菌中具有普遍性。与绿色的嗜热绿菌不同，棕色菌的叶绿体通常含有片层聚集体结构域，这可能有助于它们在极低光照条件下生存。我们认为类胡萝卜素定位于片层平面之间，并通过增强疏水相互作用来驱动片层组装。本文提出了一个叶绿体组装模型，该模型解释了类胡萝卜素和次要BChl同系物的作用。
