Barrera-Rojas Jesús, de la Vara Luis González, Ríos-Castro Emmanuel, Leyva-Castillo Lourdes E, Gómez-Lojero Carlos
Departamento de Bioquímica, Centro de Investigación y Estudios Avanzados del IPN, Mexico.
Unidad Irapuato, Centro de Investigación y Estudios Avanzados del IPN, Mexico.
Heliyon. 2018 Dec 28;4(12):e01100. doi: 10.1016/j.heliyon.2018.e01100. eCollection 2018 Dec.
The marine unicellular green cyanobacterium MIT9313 belongs to the most abundant and photosynthetically productive genus of cyanobacteria in the oceans. This monophyletic genus use divinyl chlorophyll (Chl ) and (Chl ) to build the photosystems and the membrane-intrinsic Pcb-type antennae. We used the mild detergent n-dodecyl β D-maltopyranoside to solubilize the thylakoid membranes. Gel electrophoresis and sucrose gradient ultracentrifugation was then used to separate the complexes of the photosynthetic apparatus. The proteins and the pigments were identified by mass spectrometry. Protein complexes were characterized biochemically, and the distribution of Chl and Chl was determined. The photosynthetic apparatus was shown as supercomplexes formed by Photosystem II dimers with up to eight PcbB proteins; Photosystem I was present as trimers. A heterogeneous distribution of pigments was shown using sucrose gradient-enriched fractions with ratios of [Chl ]/[Chl ] of 2.16 ± 0.13, 1.86 ± 0.08, and 2.61 ± 0.07, for Photosystem I, Photosystem II, and PcbB, respectively. These ratios of Chl / are without precedent in organisms with oxygenic photosynthesis. Diaphorase activity was measured in the fractions of the sucrose gradient. Gel electrophoresis, immunodetection, and mass spectrometry were used to conclude that the commonly soluble protein ferredoxin-NADP reductase (FNR) is a membrane-anchored protein (probably associated to cytochrome complex) in the low-light adapted MIT9313.
海洋单细胞绿色蓝细菌MIT9313属于海洋中最丰富且光合生产力最高的蓝细菌属。这个单系属利用二乙烯基叶绿素（Chl ）和（Chl ）构建光系统和膜内在的Pcb型天线。我们使用温和的去污剂正十二烷基β -D-麦芽糖苷溶解类囊体膜。然后通过凝胶电泳和蔗糖梯度超速离心分离光合装置的复合物。通过质谱鉴定蛋白质和色素。对蛋白质复合物进行生化表征，并确定Chl 和Chl 的分布。光合装置表现为由含有多达八个PcbB蛋白的光系统II二聚体形成的超级复合物；光系统I以三聚体形式存在。使用蔗糖梯度富集级分显示色素的异质分布，光系统I、光系统II和PcbB的[Chl ]/[Chl ]比率分别为2.16±0.13、1.86±0.08和2.61±0.07。这些Chl / 的比率在进行产氧光合作用的生物体中尚无先例。在蔗糖梯度级分中测量了黄递酶活性。通过凝胶电泳、免疫检测和质谱得出结论，在适应低光的MIT9313中，常见的可溶性蛋白铁氧还蛋白-NADP还原酶（FNR）是一种膜锚定蛋白（可能与细胞色素 复合物相关）。
