Substrate recognition induces sequential electron transfer across subunits in the nitrogenase-like DPOR complex

Abstract

A key step in bacteriochlorophyll biosynthesis is the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), catalyzed by dark-operative protochlorophyllide oxidoreductase (DPOR). DPOR is made of electron donor (BchL) and acceptor (BchNB) component proteins. BchNB is further composed of two subunits each of BchN and BchB arranged as an α2β2 heterotetramer with two active sites for substrate reduction. Such oligomeric architectures are found in several other electron transfer (ET) complexes, but how this architecture influences activity is unclear. Here, we describe allosteric communication between the two identical active sites in Rhodobacter sphaeroides BchNB that drives sequential and asymmetric ET. Pchlide binding to one BchNB active site initiates ET from the pre-reduced [4Fe-4S] cluster of BchNB, a process similar to the deficit spending mechanism observed in the structurally related nitrogenase complex. Pchlide binding in one active site is recognized in trans by an Asp-274 from the opposing half, which is positioned to serve as the initial proton donor. A D274A variant DPOR binds to two Pchlide molecules in the BchNB complex, but only one is bound productively, stalling Pchlide reduction in both active sites. A half-active complex combining one WT and one D274A monomer also stalled after one electron was transferred in the WT half. We propose that such sequential electron transfer in oligomeric enzymes serves as a regulatory mechanism to ensure binding and recognition of the correct substrate. The findings shed light on the functional advantages imparted by the oligomeric architecture found in many electron transfer enzymes. A key step in bacteriochlorophyll biosynthesis is the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), catalyzed by dark-operative protochlorophyllide oxidoreductase (DPOR). DPOR is made of electron donor (BchL) and acceptor (BchNB) component proteins. BchNB is further composed of two subunits each of BchN and BchB arranged as an α2β2 heterotetramer with two active sites for substrate reduction. Such oligomeric architectures are found in several other electron transfer (ET) complexes, but how this architecture influences activity is unclear. Here, we describe allosteric communication between the two identical active sites in Rhodobacter sphaeroides BchNB that drives sequential and asymmetric ET. Pchlide binding to one BchNB active site initiates ET from the pre-reduced [4Fe-4S] cluster of BchNB, a process similar to the deficit spending mechanism observed in the structurally related nitrogenase complex. Pchlide binding in one active site is recognized in trans by an Asp-274 from the opposing half, which is positioned to serve as the initial proton donor. A D274A variant DPOR binds to two Pchlide molecules in the BchNB complex, but only one is bound productively, stalling Pchlide reduction in both active sites. A half-active complex combining one WT and one D274A monomer also stalled after one electron was transferred in the WT half. We propose that such sequential electron transfer in oligomeric enzymes serves as a regulatory mechanism to ensure binding and recognition of the correct substrate. The findings shed light on the functional advantages imparted by the oligomeric architecture found in many electron transfer enzymes. Many oligomeric enzymes that transfer electrons for catalysis or substrate reduction have two identical active sites and their subunits are arranged with a head-to-head or head-to-tail symmetry. The electron acceptor component proteins of nitrogenase and the nitrogenase-like class of enzymes, such as the dark-operative protochlorophyllide oxidoreductase (DPOR) and chlorophyllide oxidoreductase, are arranged as α2β2 tetramers (Fig. 1a) (1Howard J.B. Rees D.C. Nitrogenase: A nucleotide-dependent molecular switch.Annu. Rev. Biochem. 1994; 63 (7979238): 235-26410.1146/annurev.bi.63.070194.001315Crossref PubMed Scopus (159) Google Scholar, 2Rees D.C. Howard J.B. Nitrogenase: Standing at the crossroads.Curr. Opin. Chem. Biol. 2000; 4 (11006545): 559-56610.1016/S1367-5931(00)00132-0Crossref PubMed Scopus (236) Google Scholar, 3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar, 4Moser J. Lange C. Krausze J. Rebelein J. Schubert W.D. Ribbe M.W. Heinz D.W. Jahn D. Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex.Proc. Natl. Acad. Sci. U. S. A. 2013; 110 (23341615): 2094-209810.1073/pnas.1218303110Crossref PubMed Scopus (45) Google Scholar). A similar architecture is also seen in the nitric oxide synthase (5Campbell M.G. Smith B.C. Potter C.S. Carragher B. Marletta M.A. Molecular architecture of mammalian nitric oxide synthases.Proc. Natl. Acad. Sci. U. S. A. 2014; 111 (25125509): E3614-E362310.1073/pnas.1413763111Crossref PubMed Scopus (66) Google Scholar) and ribonucleotide reductase family of enzymes (6Kang G. Taguchi A.T. Stubbe J. Drennan C.L. Structure of a trapped radical transfer pathway within a ribonucleotide reductase holocomplex.Science. 2020; 368 (32217749): 424-42710.1126/science.aba6794Crossref PubMed Scopus (27) Google Scholar). Given the evolutionary and functional significance of these enzymes, a mechanistic significance must exist behind such structural assemblies. In gymnosperms, cyanobacteria, and all photosynthetic eubacteria, DPOR catalyzes the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide) in the dark, a key step in the chlorophyll and bacteriochlorophyll biosynthetic pathways (7Reinbothe C. El Bakkouri M. Buhr F. Muraki N. Nomata J. Kurisu G. Fujita Y. Reinbothe S. Chlorophyll biosynthesis: spotlight on protochlorophyllide reduction.Trends Plant Sci. 2010; 15 (20801074): 614-62410.1016/j.tplants.2010.07.002Abstract Full Text Full Text PDF PubMed Scopus (141) Google Scholar). DPOR consists of electron donor (BchL) and electron acceptor (BchN-BchB; BchNB) component proteins (Fig. 1a) (8Fujita Y. Bauer C.E. Reconstitution of light-independent protochlorophyllide reductase from purified bchl and BchN-BchB subunits. In vitro confirmation of nitrogenase-like features of a bacteriochlorophyll biosynthesis enzyme.J. Biol. Chem. 2000; 275 (10811655): 23583-2358810.1074/jbc.M002904200Abstract Full Text Full Text PDF PubMed Scopus (117) Google Scholar, 9Fujita Y. Protochlorophyllide reduction: A key step in the greening of plants.Plant Cell Physiol. 1996; 37 (8759912): 411-42110.1093/oxfordjournals.pcp.a028962Crossref PubMed Scopus (109) Google Scholar). BchL is a homodimer containing one [4Fe-4S] cluster ligated at the dimer interface by two cysteine residues per monomer and possesses one ATP binding site per monomer (10Sarma R. Barney B.M. Hamilton T.L. Jones A. Seefeldt L.C. Peters J.W. Crystal structure of the L protein of Rhodobacter sphaeroides light-independent protochlorophyllide reductase with MgADP bound: A homologue of the nitrogenase Fe protein.Biochemistry. 2008; 47 (19006326): 13004-1301510.1021/bi801058rCrossref PubMed Scopus (54) Google Scholar). BchNB is an α2β2 tetramer carrying one [4Fe-4S] cluster and substrate (Pchlide) binding site per half of the tetramer (3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar). ATP binding to BchL drives the assembly of the BchL and BchNB proteins and the transient assembly of this complex promotes electron transfer (ET) (8Fujita Y. Bauer C.E. Reconstitution of light-independent protochlorophyllide reductase from purified bchl and BchN-BchB subunits. In vitro confirmation of nitrogenase-like features of a bacteriochlorophyll biosynthesis enzyme.J. Biol. Chem. 2000; 275 (10811655): 23583-2358810.1074/jbc.M002904200Abstract Full Text Full Text PDF PubMed Scopus (117) Google Scholar). The electron is transferred from the [4Fe-4S] cluster of BchL, to the [4Fe-4S] cluster of one half of BchNB and finally to the C17=C18 double bond of Pchlide. Two rounds of electron and proton transfer are required to reduce Pchlide to Chlide (Fig. 1b). In DPOR, one proton required for reduction originates intrinsically from within the C17 propionate of Pchlide, and the second proton is donated in trans from an Asp-274 of the opposing BchB subunit (Fig. 1c) (11Bröcker M.J. Virus S. Ganskow S. Heathcote P. Heinz D.W. Schubert W.D. Jahn D. Moser J. ATP-driven reduction by dark-operative protochlorophyllide oxidoreductase from Chlorobium tepidum mechanistically resembles nitrogenase catalysis.J. Biol. Chem. 2008; 283 (18252716): 10559-1056710.1074/jbc.M708010200Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar, 12Bröcker M.J. Wätzlich D. Saggu M. Lendzian F. Moser J. Jahn D. Biosynthesis of (bacterio)chlorophylls: ATP-dependent transient subunit interaction and electron transfer of dark operative protochlorophyllide oxidoreductase.J. Biol. Chem. 2010; 285 (20075073): 8268-827710.1074/jbc.M109.087874Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar). Chlide is subsequently reduced by the structurally homologous chlorophyllide oxido-reductase (COR) in the bacteriochlorophyll biosynthetic pathway (13Yamamoto H. Kato M. Yamanashi K. Fujita Y. Reconstitution of a sequential reaction of two nitrogenase-like enzymes in the bacteriochlorophyll biosynthetic pathway of Rhodobacter capsulatus.Biochem. Biophys. Res. Commun. 2014; 448 PubMed Scopus Google Scholar, J. Mizoguchi T. Tamiaki H. Fujita Y. A second nitrogenase-like for bacteriochlorophyll biosynthesis: Reconstitution of chlorophyllide a reductase with purified and from Rhodobacter Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). the and of bacteriochlorophyll to for these enzymes is on their are these enzymes as two functional and how substrate two rounds of ET are required for substrate BchL binding and at each BchNB half. The two BchL binding on BchNB are J. Lange C. Krausze J. Rebelein J. Schubert W.D. Ribbe M.W. Heinz D.W. Jahn D. Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex.Proc. Natl. Acad. Sci. U. S. A. 2013; 110 (23341615): 2094-209810.1073/pnas.1218303110Crossref PubMed Scopus (45) Google Scholar). their binding are allosteric communication is Here, we such mechanistic DPOR from Rhodobacter We that the two and that of substrate reduction activity at ET at the stalling the DPOR complex. The findings key functional advantages of the oligomeric architecture found in many enzymes that electron transfer the functional of the α2β2 we of DPOR and Pchlide reduction BchN and BchB are as and a a BchNB complex, we a two BchB for a or on the of Pchlide reduction as their of Pchlide reduction are similar (Fig. a and of Pchlide to Chlide in a with of an at We that on the of BchB Pchlide reduction activity BchB with an of the BchN an of BchNB tetramers carrying two two or one of each in the of a BchNB tetramer (Fig. to the of BchNB proteins and The purified BchNB complex one BchB subunit carrying a and the other a (Fig. The of the the sequential further by and (Fig. and and a half-active BchNB complex, we an Asp-274 to only in the BchB subunit carrying the Asp-274 as one of the proton for Pchlide the other from the Pchlide (Fig. Asp-274 with the Pchlide and of Asp-274 to to substrate reduction in DPOR (3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar). with WT BchN and WT a of BchB (Fig. carrying WT BchNB variant BchNB or half-active BchNB the we to the BchNB (Fig. and the of both by the (Fig. and and We Pchlide reduction activity of the WT and half-active BchNB by with Pchlide, BchL, and WT BchNB carrying Pchlide, the half-active BchNB is for Pchlide reduction (Fig. a and that two functional in the of the α2β2 BchNB tetramer are required for substrate reduction. The of in DPOR binding of Pchlide to BchNB, the binding of BchL to BchNB, and the electron transfer In ATP binding and within the BchL complex are also in substrate reduction J. T. S. Fujita Y. is a of dark-operative protochlorophyllide oxidoreductase, a nitrogenase-like from Rhodobacter 2013; PubMed Scopus Google Scholar, J. T. Mizoguchi T. Tamiaki H. S. Fujita Y. protochlorophyllide oxidoreductase substrate by an cluster in bacteriochlorophyll 2014; 4 PubMed Scopus (18) Google Scholar). the half-active BchNB proteins for Pchlide we to the stalled in the we on the of the [4Fe-4S] of BchNB the of the half-active BchNB protein after the and from we the of WT and variant DPOR to the in the electron transfer The Asp-274 in BchB is in as a proton donor to Pchlide (3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar). in Asp-274 from one half of the BchNB tetramer serves as the proton donor to the Pchlide bound to the active site of the opposing half BchNB (Fig. 1c) (3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar, 4Moser J. Lange C. Krausze J. Rebelein J. Schubert W.D. Ribbe M.W. Heinz D.W. Jahn D. Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex.Proc. Natl. Acad. Sci. U. S. A. 2013; 110 (23341615): 2094-209810.1073/pnas.1218303110Crossref PubMed Scopus (45) Google Scholar). this serves as a key communication between the two of the α2β2 BchNB The [4Fe-4S] cluster of BchNB is ligated by residues from BchN and and one from BchB R. sphaeroides (Fig. The of the BchNB [4Fe-4S] cluster have but a observed and by an T. Nomata J. Fujita Y. S. of ligated cluster in of a dark-operative protochlorophyllide reductase PubMed Scopus Google Scholar). We the of BchNB in complex with substrate and of BchL T. Nomata J. Fujita Y. S. of ligated cluster in of a dark-operative protochlorophyllide reductase PubMed Scopus Google the [4Fe-4S] cluster of BchNB is (Fig. In the [4Fe-4S] cluster of BchL a in the as (Fig. J. M. K. Fujita Y. Fe cluster is in (BchL) of dark-operative protochlorophyllide reductase from Rhodobacter PubMed Scopus (43) Google Scholar). at BchNB is observed for the [4Fe-4S] cluster of BchNB (Fig. Pchlide is to BchNB, we a in (Fig. BchNB, BchL, and Pchlide are in the of the for the [4Fe-4S] cluster for BchL is but for BchNB are observed (Fig. is as ATP binding to BchL is required to complex between BchNB and we BchL and ATP to the reaction containing BchNB in the of Pchlide, a at (Fig. and which resembles the T. Nomata J. Fujita Y. S. of ligated cluster in of a dark-operative protochlorophyllide reductase PubMed Scopus Google Scholar). that BchL a complex with BchNB in the of Pchlide and an electron to the [4Fe-4S] cluster of the reaction is with BchL, BchNB, Pchlide, and the reaction in the of the (Fig. for DPOR that the [4Fe-4S] cluster of BchNB in an The mechanism of BchNB binding to Pchlide, by complex with BchL, and the transfer of the electron from BchL to BchNB and Pchlide. In BchL reduce BchNB in the of Pchlide, we an BchNB pre-reduced in the by Pchlide and the transfer of the electron to Pchlide. is with the deficit spending mechanism for nitrogenase K. B.M. Seefeldt L.C. transfer within for a PubMed Scopus Google the electron to substrate from the pre-reduced protein is ATP-dependent reduction from the donor We the of substrate reduction in DPOR by the of the at (Fig. and the of the (Fig. containing BchL, BchNB, and Pchlide by ATP and for electron transfer and Pchlide The of the with the of at a (Fig. that the electron transfer to the [4Fe-4S] cluster of of of the behind the Chlide the the cluster on the the BchNB cluster is in a reduced and to an electron to Pchlide the substrate reduction as in the deficit spending with reduction of the BchNB by BchL in the of Pchlide (Fig. of the of Pchlide binding to BchNB is to the mechanism of ET. the BchNB we that rounds of ET one or both BchNB a in the proton donor we that a stalled BchNB for the complex. the of the of Pchlide, BchL, or the of a at of the of a reduced [4Fe-4S] cluster (Fig. is in to WT BchNB that is (Fig. that the at Asp-274 influences the of the [4Fe-4S] cluster by structural in the protein that the cluster to the in the or by a of that the reduction of the of the crystal of the M.J. S. Heinz D.W. Jahn D. Schubert W.D. Moser J. Crystal structure of the nitrogenase-like dark operative protochlorophyllide oxidoreductase complex Biol. Chem. 2010; 285 Full Text Full Text PDF PubMed Scopus Google Scholar) and BchNB (3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar) crystal that this (Fig. The of the binding in WT BchNB, in the of Pchlide, serves as a mechanism for the [4Fe-4S] cluster as the cluster is reduced of Pchlide or BchL the and the [4Fe-4S] cluster for BchNB to Pchlide in the of BchL to BchNB in the of Pchlide and an electron in the of ATP (Fig. Pchlide or BchL binding to BchNB are and a of binding substrate reduction is for Pchlide reduction but is with we ET with Pchlide, the for the [4Fe-4S] cluster of (Fig. electrons to Pchlide. The of the that the ET in both is with BchL, Pchlide, and the at is (Fig. the of the is of the of the observed for WT BchNB similar (Fig. is of a stalled of only one of the two [4Fe-4S] of BchNB The also that the at for WT BchNB the two electrons per one per BchNB half. findings further the sequential ET in DPOR in one half activity in the the two to the DPOR complex have to Pchlide reduction but this is the (Fig. in the for an the of the for have or of WT BchNB, but this is the (Fig. similar to for nitrogenase K. S. S. M. D. S. B.M. Seefeldt L.C. in the nitrogenase Fe protein electron Natl. Acad. Sci. U. S. A. PubMed Scopus Google we propose that an functional in the two in the BchNB complex to transfer electrons to Pchlide in a sequential we how is We two BchNB, is intrinsically with asymmetric Pchlide binding in between the two Pchlide binding to active site is and in the active site Pchlide binding and Pchlide binding to the other half. these we Pchlide binding by the in binding to A of the of Pchlide an and at and (Fig. on the we a of Pchlide at and the in in the and of BchNB (Fig. BchNB is to the the of Pchlide (Fig. The of Pchlide to binding to other proteins such protochlorophyllide reductase in Pchlide binding to Pchlide, as binding to also similar in The and of the catalyzed by protochlorophyllide Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). such in Pchlide to is the for Pchlide binding to the BchNB complex. reaction a in Pchlide (Fig. for BchNB, in Pchlide are an of the from Pchlide, we binding with a of Pchlide and in of the BchNB tetramer (Fig. in Pchlide is observed as a of BchNB (Fig. The a of BchNB is to all the Pchlide molecules in the an of BchNB is to the reaction the a in the Pchlide is observed (Fig. the of BchNB is in the the from a BchNB complex to a complex The of the complex is from the complex. Given the in BchNB we propose that one Pchlide is bound in a from the The to two for Pchlide bound to similar binding are with the we a similar an in Pchlide is The as observed for WT both active sites are Pchlide bound (Fig. for the is half that observed for WT that the of the bound Pchlide molecules are between and WT the protein is the in Pchlide for also from the electron transferred to Pchlide. to the the for the WT BchNB one electron transferred to each Pchlide as a step to and in the Pchlide within the active The for the also ET to the bound Pchlide molecules (Fig. In the to the proton from Asp-274 to Pchlide is In the of BchL and complex between BchNB and BchL the [4Fe-4S] cluster on The of is in the variant and Pchlide reduction is in active to asymmetric and sequential ET in the DPOR and the Asp-274 serves as a key in the electron transfer between the two The oligomeric α2β2 structural observed in the BchNB complex of DPOR is found in a of other protein complexes, in enzymes that ET enzymes have two identical active sites. In DPOR, structural between the two active sites are a with one half a key proton donor in trans to the Pchlide bound in the active site of the opposing subunit (3Muraki N. Nomata J. Ebata K. Mizoguchi T. Shiba T. Tamiaki H. Kurisu G. Fujita Y. X-ray crystal structure of the light-independent protochlorophyllide reductase.Nature. 2010; 465 (20400946): 110-11410.1038/nature08950Crossref PubMed Scopus (129) Google Scholar, 4Moser J. Lange C. Krausze J. Rebelein J. Schubert W.D. Ribbe M.W. Heinz D.W. Jahn D. Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex.Proc. Natl. Acad. Sci. U. S. A. 2013; 110 (23341615): 2094-209810.1073/pnas.1218303110Crossref PubMed Scopus (45) Google Scholar). allosteric and communication between the two the in the ET and Pchlide reduction findings this and communication between the two active sites. In the of BchNB, one site is WT and the other a D274A Pchlide reduction activity in both is in this the rounds of ET required for Pchlide reduction. The of for DPOR activity the Pchlide binding to both active sites of with to Pchlide binding to BchNB is an in the and the binding sites are structurally the of Pchlide binding to the two active sites. the active sites are to Pchlide and binding of Pchlide to one or the other site within to that the [4Fe-4S] cluster of BchNB in a reduced and is to the electron to Pchlide binding in the of In the the to the [4Fe-4S] cluster of BchNB a reduced after the of Pchlide reduction (Fig. mechanism is similar to the deficit spending for the ET in the binding of the Fe protein K. B.M. Seefeldt L.C. transfer within for a PubMed Scopus Google Scholar). this ET in both active sites of BchNB or within one site is to Such sequential ET in nitrogenase ET in one half in the other K. S. S. M. D. S. B.M. Seefeldt L.C. in the nitrogenase Fe protein electron Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, S. K. S. B.M. Seefeldt L.C. transfer ATP nitrogenase Natl. Acad. Sci. U. S. A. 2013; 110 PubMed Scopus Google Scholar). is the in pre-reduced of WT BchNB and the The [4Fe-4S] cluster of is pre-reduced and is in (Fig. The WT BchNB protein is (Fig. the [4Fe-4S] cluster between the WT and variant BchNB both proteins to two Pchlide molecules (Fig. We propose that the is to and the of Pchlide within the active site and the deficit spending mechanism an of this and of Pchlide serves two the structure of Pchlide within the active and DPOR between Pchlide and Chlide is the reduced of Pchlide and must from the active site of Chlide binds to the active site of the in the is to structurally similar to DPOR, but the between Pchlide and Chlide is one double bond in the C17=C18 of the the initial and of Pchlide by the Asp-274 serves as a substrate mechanism within the active site of The step in the DPOR mechanism is the binding of BchL to We that is to of Pchlide binding to BchNB as the by complex with BchL, these sequential or on one BchL a complex with BchNB in the of Pchlide and electrons (Fig. a of the and of complex between BchNB and The of Pchlide, required to the complex in BchL binds to BchNB, these on both of the BchNB complex. these binding are and and how to to The crystal structure of DPOR bound to the a complex with BchNB bound to BchL on both J. Lange C. Krausze J. Rebelein J. Schubert W.D. Ribbe M.W. Heinz D.W. Jahn D. Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex.Proc. Natl. Acad. Sci. U. S. A. 2013; 110 (23341615): 2094-209810.1073/pnas.1218303110Crossref PubMed Scopus (45) Google Scholar). In the of is ET from BchL to BchNB (Fig. at a complex between BchL and BchNB is transient and to ATP binding and within ET from the [4Fe-4S] cluster of BchL to the [4Fe-4S] cluster on BchNB and Pchlide complex ET within the two to that communication ET from one half is to the other of Asp-274 in one half of BchNB Pchlide reduction. the two are with to the in their Pchlide reduction In we and allosteric communication between the two K. S. S. M. D. S. B.M. Seefeldt L.C. in the nitrogenase Fe protein electron Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). ET in one half, and this process is in the a sequential ET mechanism between the two the half-active DPOR complex to reduce Pchlide in both we propose that such also in the DPOR The between DPOR and nitrogenase with to communication and between the two that sequential ET a in other such enzymes. functional advantages to such to the of and of ET. nitrogenase and DPOR substrate reduction rounds of ET. The allosteric and sequential ET process also to the of electrons that at the and on the substrate. to such mechanistic between α2β2 that reduction from and from is composed of and is to the to BchL and BchNB are of a functional pathway in of an 2020; Scholar). for BchL, and BchB from from R. sphaeroides from and BchL and BchB to an and recognition sites and and BchN and was a sites. The was as a to or or BchB Pchlide was as of a functional pathway in of an 2020; Scholar) a R. a of the BchL from (8Fujita Y. Bauer C.E. Reconstitution of light-independent protochlorophyllide reductase from purified bchl and BchN-BchB subunits. In vitro confirmation of nitrogenase-like features of a bacteriochlorophyll biosynthesis enzyme.J. Biol. Chem. 2000; 275 (10811655): 23583-2358810.1074/jbc.M002904200Abstract Full Text Full Text PDF PubMed Scopus (117) Google Scholar). BchNB and BchL protein purified as of a functional pathway in of an 2020; Scholar). The was for of the BchNB complex. and The and protein was as for the WT BchNB complex. the from or a with bound proteins with containing proteins a containing The from BchNB a with with bound proteins containing or BchNB the for and for but BchNB proteins a molecular in the which have a with protein from the and and with as was on after on transferred for with and for 15 after the with in for at with and to to in for at in at for after the an of Pchlide to Chlide was by BchNB BchL and Pchlide, in the or of ATP in containing and as a of these with of The was in a at for 4 to protein of the was transferred to a and from to on a Chlide was as the at at on an with an and an for was with a and an and with or with for the and the and at S. A. a for and in PubMed Scopus Google Scholar). for of BchL, BchNB, Pchlide, and in the BchL, BchNB, Pchlide, and in BchNB Pchlide. in the for and transferred to the in the and with a from the and in and by of BchNB and Pchlide made in the in with and for transferred to an on a at with and of and and between to a binding and are the of the and and are the binding for the two binding sites in the BchNB complex. are within the for protein are with electron transfer dark-operative protochlorophyllide oxidoreductase protochlorophyllide chlorophyllide oxido-reductase

Topics & Concepts