Febs Letters

doi: 10.1016/0014-5793(95)90140-Xpmid: N/A

doi: 10.1016/0014-5793(95)90138-8pmid: N/A

Toyokuni, Shinya; Okamoto, Keisei; Yodoi, Junji; Hiai, Hiroshi

doi: 10.1016/0014-5793(94)01368-Bpmid: 7821417

DNA of cancers such as renal cell carcinoma and mammary invasive ductal carcinoma, is persistently exposed to more oxidative stress than that of adjacent nornal tissue. We suggest that the concept of ‘persistent oxidative stress in cancer’ may open up a new research area, explaining part of the characteristic tumor biology of cancer such as activated transcription factors and proto‐oncogenes, genomic instability, chemotherapy‐resistance, invasion and metastasis.

Singh, Toolsee J.; Zaidi, Tanweer; Grundke-Iqbal, Inge; Iqbal, Khalid

doi: 10.1016/0014-5793(94)01383-Cpmid: 7821426

The phosphorylation of bovine tau, either by GSK‐3 alone or by a combination of GSK‐3 and several non‐proline‐dependent protein kinases (non‐PDPKs), was studied. GSK‐3 alone catalyzed the incorporation of ∼ 3 mol 32P/mot tau at a relatively slow rate. Prephosphorylation of tau by A‐kinase, C‐kinase, or CK‐2 (but not by CK‐1, CaM kinase II or Gr kinase) increased both the rate and extent of a subsequent phosphorylation catalyzed by GSK‐3 by several‐fold. These results suggest that the phosphorylation of tau by PDPKs such as GSK‐3 (and possibly MAP kinase, cdk5) may be positively modulated at the substrate level by non‐PDPK‐catalyzed phosphorylations.

Noguchi, Takumi; Honda, Jun; Nagamune, Teruyuki; Sasabe, Hiroyuki; Inoue, Yorinao; Endo, Isao

doi: 10.1016/0014-5793(94)01374-Apmid: 7821438

Nitrile hydratase (NHase) from Rhodococcus sp. N771 is a photosensitive enzyme that catalyzes hydration of nitriles to the corresponding amides. Light‐induced Fourier transform infrared difference spectra between the inactive and active forms of NHase were measured with both the natural (14N) and 15N‐labeled NHases. The results showed, for the first time, that NHase intrinsically possesses nitric oxide (NO) molecules bound to the non‐heme iron center. The possible role of NO in the photoactivation process of NHase is discussed.

Krajewski, Wladyslaw A.

doi: 10.1016/0014-5793(94)01377-Dpmid: 7821420

The transcriptional control region of the Rouse sarcoma virus long terminal repeats (LTR) was shown to contain enhancer and promoter elements located within 200 base pairs upstream from the transcription initiation site [Cullen et al. (1985) Mol. Cell. Biol. 5, 438–447]. Deletion of these elements results in significant loss of LTR transcriptional activity. In the present paper it is shown that a short alternating purine‐pyrimidine sequence can restore the constitutive activity of the Rouse sarcoma virus LTR in the absence of upstream elements when inserted in close proximity to the transcription initiator site. The possible molecular bases of this phenomena are discussed.

Polozova, Alla I.; Dubachev, Gennady E.; Simonova, Tatyana N.; Barsukov, Leonid I.

doi: 10.1016/0014-5793(94)01378-Epmid: 7821421

The transition states of binary mixtures of dipalmitoyl‐ and dimyristoylphosphatidylcholines with sodium cholate at the reversible temperature‐induced micellar‐lamellar transformation were characterized by turbidimetry, electron microscopy, 31P NMR and differential scanning calorimetry. This transformation is triggered by the phospholipidacyl chain melting, and appears to include two structural pathways: (i) from discoidal mixed micelles to network‐like structures composed of long interlaced rod‐like micelles, then to multilayer membrane structures, and finally to multilamellar vesicles; and (ii) from discoidal micelles to membrane fragments and finally to unilamellar vesicles.

Urquidi, Virginia; Ashcroft, Stephen J.H.

doi: 10.1016/0014-5793(94)01381-Apmid: 7821422

There is evidence for a role for calciumlcalmodulin‐dependent protein phosphorylation in regulation of insulin secretion but the molecular nature of the kinase(s) responsible is unknown. In this study, the screening of a neonatal rat islet cDNA library resulted in the isolation of a 2 kb clone that was 99% homologous to the β′ isoform of calciumlcalmodulin‐dependent protein kinase 11. The predicted 589 amino acid sequence with a caLculated mass of 64,976 Da contained a 24 amino acid deletion in addition to the 15 amino acid deletion that differentiates the β′ from the β isoform, and included an 86 amino acid novel domain consisting of a tandem repeat of proline‐rich residues. The expression of this new isoform of calciumlcalmodulin‐dependent protein kinase 11 (β 3) was confirmed in β‐cell lines and testis by DNA amplification of the sequence encoding the inserted domain by reverse transcriptase‐polymerase chain reaction, followed by Southern analysis.

Garriga, Pere; Garcia-Quintana, David; Manyosa, Joan

doi: 10.1016/0014-5793(94)01385-Epmid: 7821423

The conformational changes of poly[d(A‐C)]·poly[d(GT)] induced by Hg(CiO4)2 in aqueous solution have been studied using UV absorption and fourth derivative spectrophotometries, and FTIR spectroscopy. The UV absorption and fourth derivative spectra reflect changes in the polynucleotide stacking interactions as a result of the metal‐polynucleotide interaction. The fourth derivative spectra do not indicate a Z‐form either at low or at high metal‐to‐polynucleotide ratios. Furthermore, the infrared spectrum at high metal‐to‐polynucleotide ratio has the main features of an A‐form, in contrast with previous CD studies which proposed that the polynucleotide adopts a Z‐form under these conditions. The nature of a different conformation of the polynucleotide induced at low r‐ratios (r < 0.2) is discussed.

Acuña, Gonzalo; Shi, Wenyuan; Trudeau, Kathy; Zusman, David R.

doi: 10.1016/0014-5793(94)01389-Ipmid: 7821424

FrzE is a chemotaxis protein in Myxococcus xanthus which has sequence homology to two different chemotaxis proteins of enteric bacteria, CheA (autokinase) and CheY (phosphate acceptor) [Proc. Natl. Acad. Sci. USA 87 (1990) 5898–5902]. It was also shown that a recombinant FrzE protein was autophosphorylated when incubated in the presence of ATP and Mn2+ [J. Bacteriol. 172 (1990) 6661–6668]. In this study, we further investigated the biochemical properties of FrzE. Two recombinant proteins were produced: one containing only the ‘CheA’ domain of FrzE and the second only the ‘CheY’ domain. The CheA domain polypeptide contained the autokinase activity which was absent from the CheY domain polypeptide. The phosphorylated CheA domain polypeptide as well as the intact FrzE protein were able to transfer phosphate groups to the CheY domain peptide. These results indicate that FrzE has structural as well as functional homologies to CheA and CheY in a single polypeptide.