Structural basis for electron transport mechanism of complex I-like photosynthetic NAD(P)H dehydrogenase

Abstract

NAD(P)H dehydrogenase-like (NDH) complex NDH-1L of cyanobacteria plays a crucial role in cyclic electron flow (CEF) around photosystem I and respiration processes. NDH-1L couples the electron transport from ferredoxin (Fd) to plastoquinone (PQ) and proton pumping from cytoplasm to the lumen that drives the ATP production. NDH-1L-dependent CEF increases the ATP/NADPH ratio, and is therefore pivotal for oxygenic phototrophs to function under stress. Here we report two structures of NDH-1L from Thermosynechococcus elongatus BP-1, in complex with one Fd and an endogenous PQ, respectively. Our structures represent the complete model of cyanobacterial NDH-1L, revealing the binding manner of NDH-1L with Fd and PQ, as well as the structural elements crucial for proper functioning of the NDH-1L complex. Together, our data provides deep insights into the electron transport from Fd to PQ, and its coupling with proton translocation in NDH-1L.

Structure and mechanism of the Mrp complex, an ancient cation/proton antiporter

“…Their homologues (called antiporter-like subunits, which we will abbreviate to APLS) are found in many proton-pumping protein complexes where they are present in one to three (and recently discovered four [ Chadwick et al, 2018 ]) copies per complex, depending on the energy availability and needs of the organism ( Efremov and Sazanov, 2012 ). These include bacterial ( Baradaran et al, 2013 ; Friedrich et al, 1995 ) and mitochondrial respiratory complex I ( Fiedorczuk et al, 2016 ; Walker, 1992 ), NDH (NADH dehydrogenase-like) complex from cyanobacteria ( Laughlin et al, 2019 ; Pan et al, 2020 ; Schuller et al, 2019 ) and chloroplasts ( Sazanov et al, 1998 ), Fpo (F420:methanophenazine oxidoreductase) complex from archaea ( Baumer et al, 2000 ) as well as various membrane-bound hydrogenases ( Efremov and Sazanov, 2012 ) including MBH (membrane-bound [NiFe]-hydrogenase) complex from archaea ( Yu et al, 2018 ). These modern enzymes represent some of the largest membrane protein complexes known and are thought to have evolved from the unification of the membrane transporter Mrp-like module with the soluble NiFe-hydrogenase module, sometimes followed by the addition of an electron input module, such as the NAD-linked formate dehydrogenase in case of complex I ( Efremov and Sazanov, 2012 ).…”

A Genome-Wide Analysis of the Chloroplast NADH Dehydrogenase-like Complex in Zostera Marina: Identification, Splicing, Editing and Profiles of Expression

“…As suggested by Jobson et al, (2008) the RNA editing events could change the protein structure or interaction through the non-synonymous replacement of conserved amino acids [60,61]. Therefore, the editing events adjacent to the charged lysine residue in the TM7 helix of NdhD which was crucial for energy transduction [3], as well as in the second helix of NdhK and the N-terminal amphiphilic helix of NdhI which had an impact on quinone-binding [5], could in uence the functional NDH in Z. marina.…”

“…Cyanobacterial NDH-1 can be divided into two major parts that contain the membrane segments (NdhA-NdhG) that participate in proton translocation and the peripheral segments (NdhH-NdhK) that carry redox centers, Fe-S clusters and avin mononucleotide. The two parts form the L-shape structure which is conserved in both photosynthetic and respiratory NDH complexes [3][4][5][6]. Additionally, some new subunits that are required to stabilize the NDH complex in higher plants were found.…”

Physiological Responses of <i>Microcystis aeruginosa</i> to Extracellular Degradative Enzymes and Algicidal Substance from Heterotrophic Bacteria

“…Therefore, flavodoxin might not be the main factor which led to ROS reduction in 1-hydroxyphenazine treatments and combined treatments. In addition, there existed photosystem I-NAD(P)H dehydrogenase cyclic electron flow in cyanobacteria which only produced ATP [36]. The oxidative stress could be alleviated by the enhancement of cyclic electron transport [37].…”