Primary structure of the multifunctional alpha subunit protein of yeast fatty acid synthase derived from FAS2 gene sequence

The yeast fatty acid synthase consists of two multifunctional proteins, alpha and beta, arranged in an alpha 6 beta 6 complex with a molecular weight of 2.4 x 10(6). Five of the seven enzymatic activities reside in the beta subunit, while the remaining two activities, beta-ketoacyl synthase and beta-ketoacyl reductase, and the domain of the acyl carrier protein, with its prosthetic group, 4'-phosphopantetheine, are in the alpha subunit. The genes FAS1 and FAS2 coding for beta and alpha subunits, respectively, have been cloned and the sequence of FAS1 has been reported (Chirala, S. S., Kuziora, M. A., Spector, D. M., and Wakil, S. J. (1987) J. Biol. Chem. 262, 4231-4240). In this study, we present the nucleotide sequence of the FAS2 gene. The sequence has an open reading frame, coding for a protein of 1894 amino acids with a calculated molecular weight of 207,863. The location of the serine site of attachment of the prosthetic group of the acyl carrier protein domain and the active cysteine-SH site of beta-ketoacyl synthase have been identified at residues 180 and 1312, respectively, in the deduced amino acid sequence. A putative NADPH binding site of beta-ketoacyl reductase has been suggested at residue 1038 based on the similarities to the consensus amino acid sequences -Gly-Ser-Ala- of the pyridine nucleotide enzymes. We could not find any sequence homology in the 5' flanking sequence of the FAS1 and FAS2 genes that would suggest common regulatory function. However, in the sequence of these two genes there is an identical eight-base pair sequence TCATTATG at the translational initiation site suggesting that the subunit stoichiometry probably results from equal translational efficiency of the mRNAs of both FAS1 and FAS2 genes. The S1 endonuclease mapping suggests that there is a transcriptional initiation site at about 40 nucleotides upstream of the first ATG codon and a transcriptional termination site about 300 nucleotides downstream of the TAG stop codon. The gene does not contain introns as no intron consensus TACTAAC have been found in the sequence.

Protein modulase appears to be a complex of ferredoxin, ferredoxin/thioredoxin reductase, and thioredoxin

Protein modulase and ferredoxin/thioredoxin reductase are soluble proteins that have been suggested to catalyze the light-dependent modulation of enzyme activity in the stromal compartment of the chloroplast. Protein modulase is active in vitro without additional ferredoxin and thioredoxin, whereas ferredoxin/thioredoxin reductase requires additional ferredoxin and thioredoxin. We hypothesize that protein modulase is a complex protein composed of ferredoxin/thioredoxin reductase, ferredoxin, and thioredoxin. In reconstituted chloroplast systems, antiserum directed against ferredoxin, at concentrations sufficient to inhibit the photoreduction of NADP, had no effect on light modulation. Antiserum directed against thioredoxin gave variable results: one batch of polyclonal antibodies inhibited light modulation, another was stimulatory, and another was without effect. These results suggest that the ferredoxin and thioredoxin active in light modulation are not free in solution. Furthermore, molecular sieve chromatography of stromal proteins results in the elution of four species that catalyze light modulation. Based on whether or not ferredoxin and/or thioredoxin must be added for activity, these four species have been tentatively identified as protein modulase, a complex of ferredoxin/thioredoxin reductase and ferredoxin, a complex of ferredoxin/thioredoxin reductase and thioredoxin, and ferredoxin/thioredoxin reductase. That is, the four correspond to all the possible combinations of ferredoxin, ferredoxin/thioredoxin reductase, and thioredoxin. We suggest that buffer ionic strength affects the interactions among these proteins and in part determines the fate of the protein modulase complex in vitro.

Band 3 tyrosine kinase. Association with the human erythrocyte membrane

Band 3, the anion transport protein of the human erythrocyte membrane, is known to be phosphorylated in ghosts at tyrosine 8. The band 3 tyrosine kinase is now shown to be associated with the Triton X-100 insoluble membrane skeleton but not with spectrin or actin. The kinase was reversibly dissociated from membranes and skeletons at elevated ionic strength (50% at mu = 0.15). The binding capacity of the membranes exceeded their native complement of the kinase by at least 60-fold. Prior removal of all peripheral proteins from the cytoplasmic surface of inside-out vesicles did not diminish the rebinding of the kinase, whereas prior removal of band 3 and other accessory proteins from skeletons abolished the rebinding of the kinase. An excess of glyceraldehyde-3-P dehydrogenase, which binds to band 3 in the region of the phosphate acceptor tyrosine 8, both inhibited the phosphorylation of band 3 and released the kinase into solution. Soluble 40/45-kDa chymotryptic fragments from the cytoplasmic pole of band 3 were phosphorylated at least as well as membranous band 3 and caused the release of the kinase from Triton-extracted skeletons. Membrane skeletons lacked most of the membrane band 3, but retained most of the kinase. Nevertheless, the band 3 population solubilized by Triton X-100 from prelabeled ghosts was as well phosphorylated as the population of band 3 retained by the skeletons. Furthermore, the fraction of band 3 not associated with the skeletons following Triton X-100 extraction was a good substrate for the solubilized kinase. We conclude that this tyrosine kinase is reversibly bound to the membrane through electrostatic interactions with the polyacidic sequence surrounding the phosphate accepting tyrosine 8 on band 3. The kinase appears to be preferentially linked to those band 3 molecules associated with the membrane skeleton, but it impartially phosphorylates band 3 species free in the bilayer as well as band 3 fragments in solution. The resemblance of its plasma membrane binding behavior to that of tyrosine kinases of certain viruses causing oncogenic transformation is discussed.

Haematological and biochemical changes in buffalo calves inoculated with Sarcocystis fusiformis from cats

Two groups of buffalo calves were infected with Sarcocystis fusiformis sporocysts. Animals of the first group received each 5 X 10(5) sporocysts, those of the second group 5 million sporocysts. All calves were clinically normal during 6 weeks after infection. Minor changes were observed in the blood cytology, serum alkaline phosphatase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, total proteins, urea and glucose of infected buffalo calves.

Light Activation of Purified Aconitase by Washed Thylakoid Membranes of Pea (Pisum sativum L.)

Purified aconitase, an iron-sulfur protein, from either beef heart mitochondria or pig heart can be activated fully by light when combined with washed thylakoid membranes from pea (Pisum sativum L.) chloroplasts. The light activation of the enzyme does not require any other additive or cofactor and is sensitive to 3-(3,4-dichlorophenyl)-1,1-dimethyl urea, 2,6-dichlorophenol-indophenol, ferricyanide, and methyl viologen, indicating that the photoelectron transport system of the thylakoid membranes, and in particular, photosystem I, is involved in the process of activation. Light activation of the enzyme is also markedly inhibited when the thylakoid membranes are treated with sulfite or arsenite, and abolished totally when the membranes are treated with Zwittergent, suggesting that the light effect mediator involved in the light modulation of chloroplastic enzymes mediates the activation of purified aconitase also.

Proteins, lipids, lipoproteins and some enzyme characterizations of the venom extract from the centipede Scolopendra morsitans

Some components of Scolopendra morsitans venom extract were characterized using disc gel electrophoresis and thin layer chromatography. Its protein component was separated into 13 anodal bands and a slowly moving cathodal band. The extract showed three slowly moving lipoprotein bands and the lipid components included phospholipids, cholesterol, free fatty acids, triglycerides, cholesterol esters and squalene. The enzymes esterase, acid and alkaline phosphatases and amino acid naphthylamidase were present in multiple forms. Acid phosphatase isoenzymes were of low activity.

Cell-free synthesis of active ribulose-1,5-bisphosphate carboxylase in the mesophyll chloroplasts of Sorghum vulgare

Chloroplast and whole leaf cell RNA from Vigna sinensis, a C3 plant were used as exogenous templates for translation in a cell-free light-dependent system of isolated chloroplasts from Sorghum vulgare, a C4-type plant. Analysis of immunoprecipitates of the translated products with the total cellular RNA on sodium dodecyl sulfate polyacrylamide gels revealed the synthesis of both the subunits of ribulose-1,5-bisphosphate carboxylase. Similar analysis of the product translated with the RNA from Vigna chloroplasts, indicated the synthesis of only the large subunit of the carboxylase. Apparently the chloroplast protein synthetic machinery is capable of translating the mRNA for the smaller subunit of this protein as well, which is known to be translated in the cytoplasmic ribosomal system. Sufficient quantities of ribulose-1,5-bisphosphate carboxylase were synthesised in vitro in the preincubated chloroplast system with the whole cell RNA from the C3 plant to assay the ribulose 1,5-bisphosphate-dependent carboxylation. The newly synthesised protein in the cell-free system is identical in many ways to the native enzyme including the Mg2+ concentration-dependent shift in pH optima towards neutral side. It is specifically inhibited by anti-native ribulose-1,5-bisphosphate carboxylase and pyridoxal 5'-phosphate.

A possible mechanism of ammonium ion regulation of photosynthetic carbon flow in higher plants

Addition of NH(4) (+) to the photosynthesizing leaf cells of Dolichos lab lab L. var. Lignosis Prain and leaf discs of Vigna sinensis L. savi ex Hassk caused a significant increase in the flow of photosynthetic carbon toward amino acids with a concomitant decrease toward sugars without affecting the over-all photosynthetic rate. Similar diversion of photosynthetic carbon away from sugars was also observed in the photosynthesizing isolated chloroplasts of V. sinensis, but the latter differed in that they accumulated organic acids rather than amino acids. In an effort to understand the mechanism of NH(4) (+)-mediated regulation, the specific and total activities of NAD(P)-glutamate dehydrogenase, glutamine synthetase, pyruvate kinase, alkaline fructose 1,6-bisphosphatase, and NAD(P)-glyceraldehyde-3-phosphate dehydrogenase of the cells of D. lab lab were checked but none was affected by the added ammonium salts even after prolonged incubation. At certain concentrations, ammonium ions abolished the light activation of NADP-glyceraldehyde-3-phosphate dehydrogenase and alkaline fructose 1,6-bisphosphatase in isolated chloroplasts from dark-adapted Vigna leaves without interfering with the basal dark activity of these enzymes. Based on these observations, a possible mechanism of action of NH(4) (+) in regulating the photosynthetic carbon flow is postulated.

Ultrastructure of glycogen-rich clear cell carcinoma of the palate

Tissues from four local recurrences of a palatal tumor and regional lymph node metastases were studied by light microscopy while ultrastructural observations were made on the most recent tumor. The tumor was composed of solid sheets, clumps, and small nests of polyhedral epithelial cells with well-defined cell boundaries, clear cytoplasm, and cellular pleomorphism. Histochemical stains indicated the presence of abundant intracellular glycogen deposits in all tumor specimens examined. Ultrastructural observations revealed solid sheets of epithelial cells which lacked both surrounding basement lamina and ductal arrangements. The cytoplasm of the tumor cells was filled with beta glycogen deposits and contained scattered bundles of tonofilaments and scant organelles. The transition between the glycogen-rich tumor cells and surface epithelium showed intervening cells which contained diffusely dispersed ribosomes and small amounts of glycogen. The tumor probably originated from surface epithelium.