Febs Letters

doi: 10.1016/0014-5793(90)80868-Jpmid: N/A

Lanyi, Janos K.; Duschi, Albert; Váro, György; Zimányi, László

doi: 10.1016/0014-5793(90)80869-Kpmid: 1694779

The light‐driven chloride pump, halorhodopsin, binds and transports chloride across the membrane, and to a lesser extent nitrate. Binding and transport kinetics, and resonance Raman spectra of the retinal Schiff base, with these anions suggest the existence of two mutually exclusive binding sites. One of these may be the uptake site, and the other the release site during the transport. Plausible locations can be suggested for these sites, because halorhodopsin is a small protein with few buried positively charged residues, and the primary structure of a second pigment with similar function has recently become available for comparison.

Reinbothe, Steffen; Parthier, Benno

doi: 10.1016/0014-5793(90)80870-Opmid: 2114312

Translation of plastid messenger RNAs depends on aminoacyl‐tRNAs formed by charging plastid‐encoded tRNAs with cognate amino acids. The enzymes involved, chloroplast aminoacyl‐tRNA synthetases, are encoded in the nucleus. Both the tRNAs and the aminoacyl‐tRNA synthetases are stimulated in synthesis if dark‐grown cells are exposed to light. However, their accumulation during light‐induced chloroplast development in Euglena gracilis starts with an appreciable lag‐phase. During this period the availability of charged tRNAs probably limits protein synthesis. Due to the contemporary need of glutamyl‐tRNAGlu GAA in chlorophyll synthesis this particular tRNA is very likely depleted. Based on an analysis of glutamate codon frequency in known plastid genes, the effect of a glutamyl‐tRNAGlu GAA limitation on the translation of plastid messages is discussed.

Vaiman, Daniel; Pietrokovsky, Samuel; Cohen, Batya; Benech, Philippe; Chebath, Judith

doi: 10.1016/0014-5793(90)80871-Fpmid: 2114309

Type I and type II interferons (IFNs) can act synergistically to activate the transcription of the 2‐5A synthetase gene. We used in vivo functional assays of sequences from the gene promoter region to determine which DNA segment mediates the gene induction by IFNγ and the synergistic effect. We found that the type I IFN‐inducible enhancer (or IRS) of the 2‐5A synthetase gene also confers inducibility by type II IFN to a reporter CAT gene, though the time course and dose response of the induction by the two IFNs are quite different. A clear synergism of the two IFNs in stimulating the IRS is observed at low doses of the two IFNs.

Yamaguchi, Akihito; Adachi, Kumiko; Sawai, Tetsuo

doi: 10.1016/0014-5793(90)80872-Gpmid: 2163882

A site‐directed antibody was generated against a synthetic polypeptide corresponding to the 14 amino acid residues of the carboxyl terminus of the Tn10 TetA protein. The antibody reacted preferentially with inside‐out vesicles, rather than right‐side‐out vesicles, prepared from Escherichia coli cells harboring transposon Tn10. When inside‐out vesicles were treated with trypsin, the TetA protein was completely digested in the vicinity of the carboxyl terminus, as judged on immunoblot analysis using the antibody. In contrast, when right‐side‐out vesicles were treated with trypsin, the TetA protein was hardly digested. These results indicate that the carboxyl terminus of TetA is exposed to the cytoplasmic side of the membrane.

de Haro, M.S.López; García, C.; Nieto, A.

doi: 10.1016/0014-5793(90)80873-Hpmid: 2365051

By means of a DNA‐cellulose competitive binding assay, we have studied the interaction of the estrogen receptor with genomic fragments of the estrogen responsive rabbit uteroglobin gene. The fragments spanned from 3255 bp upstream to 1754 bp downstream of the initiation site. Only a fragment (−396/ + 8) showed strong affinity for the receptor. Within this fragment a unique palindromic sequence (GGTCAccaTGCCC) was found which is very similar to the canonical consensus sequence for the estrogen receptor. A synthetic oligonucleotide of that structure specifically competed for the binding of the receptor to DNA‐cellulose.

Martinez, I.; Ofstad, R.; Olsen, R.L.

doi: 10.1016/0014-5793(90)80874-Ipmid: 2365052

The myosin contained in white and red muscles of herring (Clupea harengus harengus) was purified, and its subunit composition analyzed by electrophoretic techniques. The only myosin isoform present in red muscles was made up of one type of heavy chain and two types of light chain. The native myosin from white muscles migrated as one wide band. Analysis of the extracts by SDS/glycerol/PAGE from white muscles revealed one main type of heavy chain. Light chains were identified by SDS‐PAGE analysis of electrophoretically purified myosin, and two‐dimensional electrophoresis of the extracts demonstrated differences in the light chain composition of white and red muscles. Using this methodology, light chain polymorphism was detected in white muscles among members of the same species.

Weiler, Rosad; Meyerson, Gabrielle; Fischer-Colbrie, Reiner; Laslop, Andrea; Påhlman, Sven; Floor, Eric; Winkler, Hans

doi: 10.1016/0014-5793(90)80875-Jpmid: 2365053

Human neuroblastoma cells were cultured either in the absence or presence of 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) known to induce neuronal differentiation. This treatment led to a marked increase in the concentration of secretogranin II but to a decrease of chromogranin A. Analogous changes were observed for the respective mRNAs. Thus during differentiation of these cells the biosynthesis of two vesicle constituents of large dense core vesicles is differentially regulated as determined both at the mRNA and the protein level. Levels of both synaptin/synaptophysin and SV2 were also elevated but to a smaller degree than that of secretogranin II.

Auer, Manfred; Kallen, Joerg; Schleischitz, Sabine; Walkinshaw, Malcolm D.; Wasserbauer, Erich; Ehn, Gerald; Lindley, Ivan J.D.

doi: 10.1016/0014-5793(90)80876-Kpmid: 2194830

Interleukin‐8 (neutrophil‐activating factor; NAP‐1) has been crystallized by the vapour diffusion technique to give single crystals suitable for three‐dimensional structural study at a resolution higher than 2.4 Å. The crystals belong to the space group P3121 or P3221 and have unit cell dimensions a = b = 40.9 Å, c = 90.3 Å.

Langgut, W.; Kersten, H.

doi: 10.1016/0014-5793(90)80877-Lpmid: 2114310

In higher eukaryotes the hypermodified guanine analogue, queuine (7‐(5‐(((1S,4S,5R)‐4,5‐dihydroxy‐2‐cyclopentene‐1‐yl)amino)‐methyl)‐7‐deazaguanine), occurs free or as modified nucleoside (Q) in the anticodon of specific tRNAs. Fast proliferating tissues and tumors contain considerable amounts of free queuine and Q‐deficient tRNAs. Here we show that HeLa cells can be grown in the absence or presence of queuine. In response to queuine, and under appropriate conditions, (i) the proliferation of HeLa cells was stimulated, (ii) the steady‐state level of c‐fos mRNA was reduced, contrary that of c‐myc mRNA was elevated, and (iii) in cytosolic extracts protein phosphorylation especially for a 42 kDa protein was significantly increased. The results suggest that queuine substitutes for growth factors in a signal transduction pathway.