Structure of ADP·AIF4–-stabilized nitrogenase complex and its implications for signal transduction

Schindelin, Hermann; Kisker, Caroline; Howard, James B.; Rees, Douglas C.

doi:10.1038/387370a0

Cited by 510 publications

(572 citation statements)

References 38 publications

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“…21 The coordination number of aluminum is variable, and is somewhat pH-dependent; 22 crystal structures of both AlF 3 and nucleotide complexes have been taken as representative of the GTP hydrolysis transition state. 19,[23][24][25] We find that the SRP GTPase heterodimer complex stabilized by binding GDP:AlF 4 has a structure that is remarkably similar to that of the complex formed in the presence of GMPPCP. The crystal structure reveals that the SRP GTPase heterodimer active site chamber has sufficient plasticity to accommodate two different nucleotide analogs at its interface, and binding of the transition-state analog is accompanied by small shifts of a sequestered water molecule and two arginine side-chains buried within the active site chamber, and small adjustments of two conserved GTPase motifs.…”

Section: Introductionmentioning

confidence: 63%

Structure of a GDP:AlF4 Complex of the SRP GTPases Ffh and FtsY, and Identification of a Peripheral Nucleotide Interaction Site

Focia

Gawronski-Salerno

Coon

et al. 2006

Journal of Molecular Biology

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The signal recognition particle (SRP) GTPases Ffh and FtsY play a central role in co-translational targeting of proteins, assembling in a GTP-dependent manner to generate the SRP targeting complex at the membrane. A suite of residues in FtsY have been identified that are essential for the hydrolysis of GTP that accompanies disengagement. We have argued previously on structural grounds that this region mediates interactions that serve to activate the complex for disengagement and term it the activation region. We report here the structure of a complex of the SRP GTPases formed in the presence of GDP:AlF 4 . This complex accommodates the putative transition-state analog without undergoing significant change from the structure of the ground-state complex formed in the presence of the GTP analog GMPPCP. However, small shifts that do occur within the shared catalytic chamber may be functionally important. Remarkably, an external nucleotide interaction site was identified at the activation region, revealed by an unexpected contaminating GMP molecule bound adjacent to the catalytic chamber. This site exhibits conserved sequence and structural features that suggest a direct interaction with RNA plays a role in regulating the activity of the SRP targeting complex.

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Section: Introductionmentioning

confidence: 63%

Structure of a GDP:AlF4 Complex of the SRP GTPases Ffh and FtsY, and Identification of a Peripheral Nucleotide Interaction Site

Focia

Gawronski-Salerno

Coon

et al. 2006

Journal of Molecular Biology

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“…The high affinity that MBP displays for MalFGK 2 in the presence of vanadate is reminiscent of the interaction between the Ras-GTPase and its regulatory protein, GTPase-activating protein (GAP), and between the two components of nitrogenase (40,41). The basal rate of GTP hydrolysis by Ras is very slow, and GAP stimulates the activity by several orders of magnitude (42).…”

Section: Discussionmentioning

confidence: 99%

Trapping the transition state of an ATP-binding cassette transporter: Evidence for a concerted mechanism of maltose transport

Chen¹

2001

Proceedings of the National Academy of Sciences

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High-affinity uptake into bacterial cells is mediated by a large class of periplasmic binding protein-dependent transport systems, members of the ATP-binding cassette superfamily. In the maltose transport system of Escherichia coli, the periplasmic maltose-binding protein binds its substrate maltose with high affinity and, in addition, stimulates the ATPase activity of the membrane-associated transporter when maltose is present. Vanadate inhibits maltose transport by trapping ADP in one of the two nucleotidebinding sites of the membrane transporter immediately after ATP hydrolysis, consistent with its ability to mimic the transition state of the ␥-phosphate of ATP during hydrolysis. Here we report that the maltose-binding protein becomes tightly associated with the membrane transporter in the presence of vanadate and simultaneously loses its high affinity for maltose. These results suggest a general model explaining how ATP hydrolysis is coupled to substrate transport in which a binding protein stimulates the ATPase activity of its cognate transporter by stabilizing the transition state.A TP binding cassette (ABC) transporters are found in each of the phylogenetic kingdoms (1). ABC proteins have been identified that function in an increasing variety of uptake and efflux functions, including nutrient transport, protein and peptide transport, polysaccharide transport, and ion transport. Some ABC transporters function as multidrug efflux pumps in both prokaryotes and eukaryotes, and overexpression of the mammalian multidrug resistance protein MDR is sometimes responsible for multidrug resistance after chemotherapy in human cancer (2). Several human diseases have been traced to ABC proteins, including cystic fibrosis, hyperinsulinemia, and macular dystrophy (1, 3-5), making it important to understand their mechanism of action. The maltose transport system, one of at least 50 such systems in Escherichia coli (6), is well characterized both genetically and biochemically and provides an excellent model system for study of the ABC family (7). It consists of a periplasmic maltose-binding protein (MBP) and a multisubunit ABC transporter (MalFGK 2 ) containing two membrane integral subunits (MalF and MalG) and two copies of a peripheral subunit (MalK) that hydrolyzes ATP (7,8). MBP functions as the primary receptor for maltose, undergoing a conformational change to encapsulate the sugar and generate a high-affinity protein-ligand complex (9, 10). Maltose-loaded MBP then interacts with MalFGK 2 to stimulate ATP hydrolysis by MalK (11) and initiate the transport process. The mechanism by which MBP stimulates ATP hydrolysis is unknown, nor is it known how maltose is transferred from the high-affinity site in MBP to MalFGK 2 .We believe that many of these details can be elucidated by stabilizing and characterizing intermediates in the transport pathway. Vanadate, an analogue of inorganic phosphate, acts as a potent inhibitor of many ATPases, presumably because it can mimic the transition state for the ␥-phosphate of ATP during...

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“…ATP-dependent electron transfer has been most extensively investigated for the two nitrogenase components 21,22 . Crystal structures of the nitrogenase complex with different nucleotides bound revealed large conformational changes on the electron-donating Fe-protein 23,24 . The electronaccepting metal clusters of the MoFe-protein are unperturbed in the known structures, but yet unobserved conformational changes on the MoFe-protein, which could gate electron transfer, appear plausible 25 .…”

Section: Discussionmentioning

confidence: 99%

ATP-induced electron transfer by redox-selective partner recognition

et al. 2014

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Thermodynamically unfavourable electron transfers are enabled by coupling to an energysupplying reaction. How the energy is transduced from the exergonic to the endergonic process is largely unknown. Here we provide the structural basis for an energy transduction process in the reductive activation of B 12 -dependent methyltransferases. The transfer of one electron from an activating enzyme to the cobalamin cofactor is energetically uphill and relies on coupling to an ATPase reaction. Our results demonstrate that the key to coupling is, besides the oxidation state-dependent complex formation, the conformational gating of the electron transfer. Complex formation induces a substitution of the ligand at the electronaccepting Co ion. Addition of ATP initiates electron transfer by provoking conformational changes that destabilize the complex. We show how remodelling of the electron-accepting Co 2 þ promotes ATP-dependent electron transfer; an efficient strategy not seen in other electron-transferring ATPases.

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Structure of ADP·AIF4–-stabilized nitrogenase complex and its implications for signal transduction

Cited by 510 publications

References 38 publications

Structure of a GDP:AlF4 Complex of the SRP GTPases Ffh and FtsY, and Identification of a Peripheral Nucleotide Interaction Site

Structure of a GDP:AlF4 Complex of the SRP GTPases Ffh and FtsY, and Identification of a Peripheral Nucleotide Interaction Site

Trapping the transition state of an ATP-binding cassette transporter: Evidence for a concerted mechanism of maltose transport

ATP-induced electron transfer by redox-selective partner recognition

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