共查询到20条相似文献，搜索用时 15 毫秒
1.
Zhang P Smith-Nguyen EV Keshwani MM Deal MS Kornev AP Taylor SS 《Science (New York, N.Y.)》2012,335(6069):712-716
In its physiological state, cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) is a tetramer that contains a regulatory (R) subunit dimer and two catalytic (C) subunits. We describe here the 2.3 angstrom structure of full-length tetrameric RIIβ(2):C(2) holoenzyme. This structure showing a dimer of dimers provides a mechanistic understanding of allosteric activation by cAMP. The heterodimers are anchored together by an interface created by the β4-β5 loop in the RIIβ subunit, which docks onto the carboxyl-terminal tail of the adjacent C subunit, thereby forcing the C subunit into a fully closed conformation in the absence of nucleotide. Diffusion of magnesium adenosine triphosphate (ATP) into these crystals trapped not ATP, but the reaction products, adenosine diphosphate and the phosphorylated RIIβ subunit. This complex has implications for the dissociation-reassociation cycling of PKA. The quaternary structure of the RIIβ tetramer differs appreciably from our model of the RIα tetramer, confirming the small-angle x-ray scattering prediction that the structures of each PKA tetramer are different. 相似文献
2.
3.
In the crystal structure of the membrane-embedded rotor ring of the sodium ion-translocating adenosine 5'-triphosphate (ATP) synthase of Ilyobacter tartaricus at 2.4 angstrom resolution, 11 c subunits are assembled into an hourglass-shaped cylinder with 11-fold symmetry. Sodium ions are bound in a locked conformation close to the outer surface of the cylinder near the middle of the membrane. The structure supports an ion-translocation mechanism in the intact ATP synthase in which the binding site converts from the locked conformation into one that opens toward subunit a as the rotor ring moves through the subunit a/c interface. 相似文献
4.
The 2.0-angstrom structure of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) catalytic subunit bound to a deletion mutant of a regulatory subunit (RIalpha) defines a previously unidentified extended interface. The complex provides a molecular mechanism for inhibition of PKA and suggests how cAMP binding leads to activation. The interface defines the large lobe of the catalytic subunit as a stable scaffold where Tyr247 in the G helix and Trp196 in the phosphorylated activation loop serve as anchor points for binding RIalpha. These residues compete with cAMP for the phosphate binding cassette in RIalpha. In contrast to the catalytic subunit, RIalpha undergoes major conformational changes when the complex is compared with cAMP-bound RIalpha. The inhibitor sequence docks to the active site, whereas the linker, also disordered in free RIalpha, folds across the extended interface. The beta barrel of cAMP binding domain A, which is the docking site for cAMP, remains largely intact in the complex, whereas the helical subdomain undergoes major reorganization. 相似文献
5.
F(1) is an adenosine triphosphate (ATP)-driven motor in which three torque-generating β subunits in the α(3)β(3) stator ring sequentially undergo conformational changes upon ATP hydrolysis to rotate the central shaft γ unidirectionally. Although extensive experimental and theoretical work has been done, the structural basis of cooperative torque generation to realize the unidirectional rotation remains elusive. We used high-speed atomic force microscopy to show that the rotorless F(1) still "rotates"; in the isolated α(3)β(3) stator ring, the three β subunits cyclically propagate conformational states in the counterclockwise direction, similar to the rotary shaft rotation in F(1). The structural basis of unidirectionality is programmed in the stator ring. These findings have implications for cooperative interplay between subunits in other hexameric ATPases. 相似文献
6.
Sambongi Y Iko Y Tanabe M Omote H Iwamoto-Kihara A Ueda I Yanagida T Wada Y Futai M 《Science (New York, N.Y.)》1999,286(5445):1722-1724
F0F1, found in mitochondria or bacterial membranes, synthesizes adenosine 5'-triphosphate (ATP) coupling with an electrochemical proton gradient and also reversibly hydrolyzes ATP to form the gradient. An actin filament connected to a c subunit oligomer of F0 was able to rotate by using the energy of ATP hydrolysis. The rotary torque produced by the c subunit oligomer reached about 40 piconewton-nanometers, which is similar to that generated by the gamma subunit in the F1 motor. These results suggest that the gamma and c subunits rotate together during ATP hydrolysis and synthesis. Thus, coupled rotation may be essential for energy coupling between proton transport through F0 and ATP hydrolysis or synthesis in F1. 相似文献
7.
Adenosine monophosphate is required for the activation of glycogen phosphorylase b and for release of the inhibition of phosphorylase a by glucose. Two molecules of adenosine monophosphate (AMP) bind to symmetry related sites at the subunit interface of the phosphorylase dimer. Adenosine triphosphate (ATP) binds to the same site, but does not promote catalytic activity. The structure of glucose-inhibited phosphorylase a bound to AMP and also of the complex formed with glucose and ATP is described. Crystallographic refinement of these complexes reveals that structural changes are associated with AMP but not ATP binding. The origin of these effects can be traced to different effector binding modes exhibited by AMP and ATP, respectively. The conformational changes associated with AMP binding traverse multiple paths in the enzyme and link the effector and catalytic sites. 相似文献
8.
The 5'-AMP (adenosine monophosphate)-activated protein kinase (AMPK) coordinates metabolic function with energy availability by responding to changes in intracellular ATP (adenosine triphosphate) and AMP concentrations. Here, we report crystal structures at 2.9 and 2.6 A resolution for ATP- and AMP-bound forms of a core alphabetagamma adenylate-binding domain from the fission yeast AMPK homolog. ATP and AMP bind competitively to a single site in the gamma subunit, with their respective phosphate groups positioned near function-impairing mutants. Unexpectedly, ATP binds without counterions, amplifying its electrostatic effects on a critical regulatory region where all three subunits converge. 相似文献
9.
DNA螺旋酶中的GyrA与GyrB亚基只有互作重组后才有酶活性。为寻找GyrB亚基和GyrA亚基相互作用的关键区域,构建了不同的GyrB亚基突变体,分析GyrB各突变体与GyrA亚基的相互作用对全酶活性的影响。结果显示:GyrB亚基C端是其与GyrA相互作用的主要结构域,结合GyrB的二维结构,提出GyrB中第531~550位氨基酸是影响螺旋酶功能的关键区域,并可能是理想的新药设计靶标。 相似文献
10.
Andersen CB Ballut L Johansen JS Chamieh H Nielsen KH Oliveira CL Pedersen JS Séraphin B Le Hir H Andersen GR 《Science (New York, N.Y.)》2006,313(5795):1968-1972
In higher eukaryotes, a multiprotein exon junction complex is deposited on spliced messenger RNAs. The complex is organized around a stable core, which serves as a binding platform for numerous factors that influence messenger RNA function. Here, we present the crystal structure of a tetrameric exon junction core complex containing the DEAD-box adenosine triphosphatase (ATPase) eukaryotic initiation factor 4AIII (eIF4AIII) bound to an ATP analog, MAGOH, Y14, a fragment of MLN51, and a polyuracil mRNA mimic. eIF4AIII interacts with the phosphate-ribose backbone of six consecutive nucleotides and prevents part of the bound RNA from being double stranded. The MAGOH and Y14 subunits lock eIF4AIII in a prehydrolysis state, and activation of the ATPase probably requires only modest conformational changes in eIF4AIII motif I. 相似文献
11.
The crystal structure of the high-affinity Escherichia coli MetNI methionine uptake transporter, a member of the adenosine triphosphate (ATP)-binding cassette (ABC) family, has been solved to 3.7 angstrom resolution. The overall architecture of MetNI reveals two copies of the adenosine triphosphatase (ATPase) MetN in complex with two copies of the transmembrane domain MetI, with the transporter adopting an inward-facing conformation exhibiting widely separated nucleotide binding domains. Each MetI subunit is organized around a core of five transmembrane helices that correspond to a subset of the helices observed in the larger membrane-spanning subunits of the molybdate (ModBC) and maltose (MalFGK) ABC transporters. In addition to the conserved nucleotide binding domain of the ABC family, MetN contains a carboxyl-terminal extension with a ferredoxin-like fold previously assigned to a conserved family of regulatory ligand-binding domains. These domains separate the nucleotide binding domains and would interfere with their association required for ATP binding and hydrolysis. Methionine binds to the dimerized carboxyl-terminal domain and is shown to inhibit ATPase activity. These observations are consistent with an allosteric regulatory mechanism operating at the level of transport activity, where increased intracellular levels of the transported ligand stabilize an inward-facing, ATPase-inactive state of MetNI to inhibit further ligand translocation into the cell. 相似文献
12.
The motor protein kinesin moves along microtubules, driven by adenosine triphosphate (ATP) hydrolysis. However, it remains unclear how kinesin converts the chemical energy into mechanical movement. We report crystal structures of monomeric kinesin KIF1A with three transition-state analogs: adenylyl imidodiphosphate (AMP-PNP), adenosine diphosphate (ADP)-vanadate, and ADP-AlFx (aluminofluoride complexes). These structures, together with known structures of the ADP-bound state and the adenylyl-(beta,gamma-methylene) diphosphate (AMP-PCP)-bound state, show that kinesin uses two microtubule-binding loops in an alternating manner to change its interaction with microtubules during the ATP hydrolysis cycle; loop L11 is extended in the AMP-PNP structure, whereas loop L12 is extended in the ADP structure. ADP-vanadate displays an intermediate structure in which a conformational change in two switch regions causes both loops to be raised from the microtubule, thus actively detaching kinesin. 相似文献
13.
DNA gyrase and the supercoiling of DNA 总被引：101，自引：0，他引：101
N R Cozzarelli 《Science (New York, N.Y.)》1980,207(4434):953-960
Negative supercoiling of bacterial DNA by DNA gyrase influences all metabolic processes involving DNA and is essential for replication. Gyrase supercoils DNA by a mechanism called sign inversion, whereby a positive supercoil is directly inverted to a negative one by passing a DNA segment through a transient double-strand break. Reversal of this scheme relaxes DNA, and this mechanism also accounts for the ability of gyrase to catenate and uncatenate DNA rings. Each round of supercoiling is driven by a conformational change induced by adenosine triphosphate (ATP) binding: ATP hydrolysis permits fresh cycles. The inhibition of gyrase by two classes of antimicrobials reflects its composition from two reversibly associated subunits. The A subunit is particularly associated with the concerted breakage-and-rejoining of DNA and the B subunit mediates energy transduction. Gyrase is a prototype for a growing class of prokaryotic and eukaryotic topoisomerases that interconvert complex forms by way of transient double-strand breaks. 相似文献
14.
Micelles protect membrane complexes from solution to vacuum 总被引：1，自引：0，他引：1
The ability to maintain interactions between soluble protein subunits in the gas phase of a mass spectrometer gives critical insight into the stoichiometry and interaction networks of protein complexes. Conversely, for membrane protein complexes in micelles, the transition into the gas phase usually leads to the disruption of interactions, particularly between cytoplasmic and membrane subunits, and a mass spectrum dominated by large aggregates of detergent molecules. We show that by applying nanoelectrospray to a micellar solution of a membrane protein complex, the heteromeric adenosine 5'-triphosphate (ATP)-binding cassette transporter BtuC2D2, we can maintain the complex intact in the gas phase of a mass spectrometer. Dissociation of either transmembrane (BtuC) or cytoplasmic (BtuD) subunits uncovers modifications to the transmembrane subunits and cooperative binding of ATP. By protecting a membrane protein complex within a n-dodecyl-beta-d-maltoside micelle, we demonstrated a powerful strategy that will enable the subunit stoichiometry and ligand-binding properties of membrane complexes to be determined directly, by precise determination of the masses of intact complexes and dissociated subunits. 相似文献
15.
Kuznedelov K Minakhin L Niedziela-Majka A Dove SL Rogulja D Nickels BE Hochschild A Heyduk T Severinov K 《Science (New York, N.Y.)》2002,295(5556):855-857
In bacteria, promoter recognition depends on the RNA polymerase sigma subunit, which combines with the catalytically proficient RNA polymerase core to form the holoenzyme. The major class of bacterial promoters is defined by two conserved elements (the -10 and -35 elements, which are 10 and 35 nucleotides upstream of the initiation point, respectively) that are contacted by sigma in the holoenzyme. We show that recognition of promoters of this class depends on the "flexible flap" domain of the RNA polymerase beta subunit. The flap interacts with conserved region 4 of sigma and triggers a conformational change that moves region 4 into the correct position for interaction with the -35 element. Because the flexible flap is evolutionarily conserved, this domain may facilitate promoter recognition by specificity factors in eukaryotes as well. 相似文献
16.
The dynamics and polarity of actin filaments are controlled by a conformational change coupled to the hydrolysis of adenosine 5'-triphosphate (ATP) by a mechanism that remains to be elucidated. Actin modified to block polymerization was crystallized in the adenosine 5'-diphosphate (ADP) state, and the structure was solved to 1.54 angstrom resolution. Compared with previous ATP-actin structures from complexes with deoxyribonuclease I, profilin, and gelsolin, monomeric ADP-actin is characterized by a marked conformational change in subdomain 2. The successful crystallization of monomeric actin opens the way to future structure determinations of actin complexes with actin-binding proteins such as myosin. 相似文献
17.
A tight coupling between adenosine triphosphate (ATP) hydrolysis and vectorial ion transport has to be maintained by ATP-consuming ion pumps. We report two crystal structures of Ca2+-bound sarco(endo)plasmic reticulum Ca2+-adenosine triphosphatase (SERCA) at 2.6 and 2.9 angstrom resolution in complex with (i) a nonhydrolyzable ATP analog [adenosine (beta-gamma methylene)-triphosphate] and (ii) adenosine diphosphate plus aluminum fluoride. SERCA reacts with ATP by an associative mechanism mediated by two Mg2+ ions to form an aspartyl-phosphorylated intermediate state (Ca2-E1 approximately P). The conformational changes that accompany the reaction with ATP pull the transmembrane helices 1 and 2 and close a cytosolic entrance for Ca2+, thereby preventing backflow before Ca2+ is released on the other side of the membrane. 相似文献
18.
A mutation in the catalytic subunit of cAMP-dependent protein kinase that disrupts regulation 总被引：8，自引：0，他引：8
L R Levin J Kuret K E Johnson S Powers S Cameron T Michaeli M Wigler M J Zoller 《Science (New York, N.Y.)》1988,240(4848):68-70
A mutant catalytic subunit of adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase has been isolated from Saccharomyces cerevisiae that is no longer subject to regulation yet retains its catalytic activity. Biochemical analysis of the mutant subunit indicates a 100-fold decreased affinity for the regulatory subunit. The mutant catalytic subunit exhibits approximately a threefold increase in Michaelis constant for adenosine triphosphate and peptide cosubstrates, and is essentially unchanged in its catalytic rate. The nucleotide sequence of the mutant gene contains a single nucleotide change resulting in a threonine-to-alanine substitution at amino acid 241. This residue is conserved in other serine-threonine protein kinases. These results identify this threonine as an important contact between catalytic and regulatory subunits but only a minor contact in substrate recognition. 相似文献
19.
Oakhill JS Steel R Chen ZP Scott JW Ling N Tam S Kemp BE 《Science (New York, N.Y.)》2011,332(6036):1433-1435
The adenosine monophosphate (AMP)-activated protein kinase (AMPK) regulates whole-body and cellular energy balance in response to energy demand and supply. AMPK is an αβγ heterotrimer activated by decreasing concentrations of adenosine triphosphate (ATP) and increasing AMP concentrations. AMPK activation depends on phosphorylation of the α catalytic subunit on threonine-172 (Thr(172)) by kinases LKB1 or CaMKKβ, and this is promoted by AMP binding to the γ subunit. AMP sustains activity by inhibiting dephosphorylation of α-Thr(172), whereas ATP promotes dephosphorylation. Adenosine diphosphate (ADP), like AMP, bound to γ sites 1 and 3 and stimulated α-Thr(172) phosphorylation. However, in contrast to AMP, ADP did not directly activate phosphorylated AMPK. In this way, both ADP/ATP and AMP/ATP ratios contribute to AMPK regulation. 相似文献
20.
Adenosine triphosphate (ATP) synthase contains a rotary motor involved in biological energy conversion. Its membrane-embedded F0 sector has a rotation generator fueled by the proton-motive force, which provides the energy required for the synthesis of ATP by the F1 domain. An electron density map obtained from crystals of a subcomplex of yeast mitochondrial ATP synthase shows a ring of 10 c subunits. Each c subunit forms an alpha-helical hairpin. The interhelical loops of six to seven of the c subunits are in close contact with the gamma and delta subunits of the central stalk. The extensive contact between the c ring and the stalk suggests that they may rotate as an ensemble during catalysis. 相似文献