Affinity labeling of purified Ca2+,Mg2+-activated ATPase of Escherichia coli by the 2',3'-dialdehydes of adenosine 5'-di- and triphosphates

Novel fluorescent labelled affinity probes for diadenosine-5',5'''-P1,P4-tetraphosphate (Ap4A)-binding studies

Tandem synthetic-biosynthetic procedures were used to prepare two novel fluorescent labelled affinity probes for diadenosine-5',5'''-P1,P4-tetraphosphate (Ap4A)-binding studies. These compounds (dial-mant-Ap4A and azido-mant-Ap4A) are shown to clearly distinguish known Ap4A-binding proteins from Escherichia coli (LysU and GroEL) and a variety of other control proteins. Successful labelling of chaperonin GroEL appears to be allosteric with respect to the well-characterized adenosine 5'-triphosphate (ATP)-binding site, suggesting that GroEL possesses a distinct Ap4A-binding site.

Photoaffinity cross-linking of F1ATPase from spinach chloroplasts by 3'-arylazido-beta-alanyl-8-azido ATP

UV irradiation of the ATPase (CF1) from spinach chloroplasts in the presence of 3'-arylazido-beta-alanyl-8-azido ATP (8,3'-DiN3ATP) results in a nucleotide-dependent inactivation of the enzyme and in a nucleotide-dependent formation of alpha-beta cross-links. The results demonstrate an interfacial localization of the nucleotide binding sites on CF1.

Loss of protection by nucleotides against proteolysis and thiol modification in the isolated alpha-subunit from F1 ATPase of Escherichia coli mutant uncA401

Binding of nucleotides to the high-affinity site of the isolated alpha subunit of normal Escherichia coli F1 adenosine triphosphatase (ATPase) results in partial protection against digestion by trypsin [Senda, Kanazawa, Tsuchiya & Futai (1983) Arch. Biochem. Biophys. 220, 398-440]. In contrast, the isolated alpha subunit from the defective ATPase of the E. coli uncA401 mutant (strain AN120) is cleaved by trypsin to peptides of less than 8000 Da in the presence of ADP or ATP (2.5 microM-110 mM). The nucleotide-dependent accessibility of thiol groups of the isolated alpha subunit was also studied. Two out of four thiol groups of the alpha subunit from normal ATPase are labelled by fluorescent maleimides or iodoacetates, but in the presence of ADP or ATP (0.14-1.2 mM), reaction of thiol groups with these labels is almost absent. Mutant alpha subunit, however, is labelled by these reagents at all four thiol groups in the presence or absence of ADP or ATP (1 mM). These results suggest that the mutation in the ATPase of strain AN120 leads either to the loss of the high-affinity nucleotide-binding site or affects transmission of allosteric changes that occur on binding of nucleotide to the isolated alpha subunit.

Inactivation of beef heart mitochondrial F1-ATPase by the 2',3'-dialdehyde derivatives of adenine nucleotides

Beef heart mitochondrial F1-ATPase was inactivated by the 2',3'-dialdehyde derivatives of ATP, ADP and AMP (oATP, oADP, oAMP). In the absence of Mg2+, inactivation resulted from the binding of 1 mol nucleotide analog per active unit of F1. The most efficient analog was oADP, followed by oAMP and oATP. Complete inactivation was correlated with the binding of about 11 mol [14C]oADP/mol F1. After correction for non-specific labeling, the number of specifically bound [14C]oADP was 2-3 mol per mol F1. By SDS-polyacrylamide gel electrophoresis, [14C]oADP was found to bind covalently mainly to the alpha and beta subunits. In the presence of Mg2+, oATP behaved as a substrate and was slowly hydrolyzed.

F1ATPase of Escherichia coli: a mutation (uncA401) located in the middle of the alpha subunit affects the conformation essential for F1 activity

F1ATPase from the Escherichia coli mutant of H+-ATPase, AN120 (uncA401), has less than 1% of the wild type activity and has been shown to be defective in the alpha subunit by in vitro reconstitution experiments. In the present study, the mutation site was located within a domain of the subunit by recombinant DNA technology. For this, a series of recombinant plasmids carrying various portions of the alpha subunit gene were constructed and used for genetic recombination with AN120. Analysis of the recombinants indicated that the mutation site could be located between amino acid residues 370 and 387. The biochemical properties of the mutant F1 were analyzed further using the fluorescent ATP analog DNS-ATP (2'-(5-dimethylaminonaphthalene-1-sulfonyl)-amino-2'-deoxy ATP). The single turnover process of E. coli F1ATPase proposed by Matsuoka et al. [(1982) J. Biochem. 92, 1383-1398.] was compared in the mutant and wild type F1's. Mutant F1 bound DNS-ATP and hydrolyzed it as efficiently as wild type F1. Results showed that binding of ATP to a low affinity site, possibly in the beta subunit, caused decrease of fluorescence of DNS-ATP in the wild type F1 and that this effect of ATP binding was inhibited by DCCD (dicyclohexyl carbodiimide). However, this effect was not inhibited by DCCD in the mutant F1, suggesting that in the proposed process some step(s) after ATP binding to the low affinity site differed in the mutant and wild F1's. When Pi was added to F1 bound to DNS-ATP or to aurovertin, a fluorescent probe capable of binding to the beta subunit, the opposite changes of fluorescence of these probes in the mutant and wild type F1's were observed, suggesting that the conformational change induced by phosphate binding was altered in the mutant F1. On the basis of the estimated mutation site and the biochemical properties of the mutant F1, the correlation of the domain of this site in the alpha subunit with the function of F1 ATPase is discussed.

Intracistronic mapping of the defective site and the biochemical properties of beta subunit mutants of Escherichia coli H+-ATPase: correlation of structural domains with functions of the beta subunit

Sixteen mutants of Escherichia coli defective in H+-ATPase (proton-translocating ATPase) were tested for their ability to recombine with hybrid plasmids carrying various portions of the beta subunit cistron. Twelve mutations were mapped within the carboxyl half of the cistron corresponding to amino acid residues 279 to 459 (domain II), while four mutations were mapped within residues 17 to 278 (domain I). The biochemical properties of these mutants were analyzed in terms of the proton permeability of their membranes and the assembly properties of their F1F0 complex. The mutants were classified according to the properties into three types, I, II, and III. In 12 mutants of type I, proton conduction in membrane vesicles was blocked and little F1 was released from the membranes under conditions in which F1 could be released from wild-type membranes, suggesting that assembly of the F1F0 complex is structurally and functionally defective. F1 was partially purified with very low recovery from one of the type I mutants, KF16. ATPase activity was reconstituted from this F1 with the beta subunit of the wild type, confirming the genetic results. Only one mutant, KF38, was classified as type II. Its membranes were partially leaky to protons and its F1 was releasable, suggesting that the interaction of its F1 and F0 was unstable. Type III mutants, KF11 and KF43, had an F1F0 complex with very low activity, in which the structure of F1 was relatively similar to that of the wild type. F1 was purified as a single complex from KF43 in this study and from KF11 previously (H. Kanazawa, Y. Horiuchi, M. Takagi, Y. Ishino, and M. Futai (1980) J. Biochem. 88, 695-703). Reconstitution experiments in vitro showed that the F1's of both mutants were defective in the beta subunit. The properties of the altered F1 of KF43 differed from those of F1 of KF11, suggesting that the mutation sites of KF43 and KF11 were different. From the results of mapping mutation sites and the biochemical properties of the mutants, the correlation of structural domains with function of the beta subunit is discussed. Most type I and type II mutations except that of KF39 were mapped in domain II, while the type III mutations were mapped in domain I, suggesting that domain II is more important than domain I for the function of the beta subunit, especially in terms of proper assembly of the F1F0 complex.