Fernandes Ana P, Nunes Tiago C, Paquete Catarina M, Salgueiro Carlos A
UCIBIO-Requimte, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal.
Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal.
Biochem J. 2017 Feb 20;474(5):797-808. doi: 10.1042/BCJ20161022.
bacteria usually prevail among other microorganisms in soils and sediments where Fe(III) reduction has a central role. This reduction is achieved by extracellular electron transfer (EET), where the electrons are exported from the interior of the cell to the surrounding environment. Periplasmic cytochromes play an important role in establishing an interface between inner and outer membrane electron transfer components. In addition, periplasmic cytochromes, in particular nanowire cytochromes that contain at least 12 haem groups, have been proposed to play a role in electron storage in conditions of an environmental lack of electron acceptors. Up to date, no redox partners have been identified in , and concomitantly, the EET and electron storage mechanisms remain unclear. In this work, NMR chemical shift perturbation measurements were used to probe for an interaction between the most abundant periplasmic cytochrome PpcA and the dodecahaem cytochrome GSU1996, one of the proposed nanowire cytochromes in The perturbations on the haem methyl signals of GSU1996 and PpcA showed that the proteins form a transient redox complex in an interface that involves haem groups from two different domains located at the C-terminal of GSU1996. Overall, the present study provides for the first time a clear evidence for an interaction between periplasmic cytochromes that might be relevant for the EET and electron storage pathways in .
在铁（III）还原起核心作用的土壤和沉积物中，细菌通常在其他微生物中占主导地位。这种还原是通过细胞外电子转移（EET）实现的，即电子从细胞内部输出到周围环境。周质细胞色素在建立内膜和外膜电子转移成分之间的界面中起重要作用。此外，有人提出周质细胞色素，特别是含有至少12个血红素基团的纳米线细胞色素，在环境缺乏电子受体的条件下在电子储存中起作用。到目前为止，尚未在[具体物种名称未给出]中鉴定出氧化还原伙伴，因此，EET和电子储存机制仍不清楚。在这项工作中，核磁共振化学位移扰动测量被用于探测最丰富的周质细胞色素PpcA与十二血红素细胞色素GSU1996（[具体物种名称未给出]中提出的纳米线细胞色素之一）之间的相互作用。GSU1996和PpcA血红素甲基信号的扰动表明，这两种蛋白质在一个界面中形成了一个瞬时氧化还原复合物，该界面涉及位于GSU1996 C末端的两个不同结构域的血红素基团。总体而言，本研究首次为周质细胞色素之间的相互作用提供了明确证据，这种相互作用可能与[具体物种名称未给出]中的EET和电子储存途径相关。
