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1.
Pectinolytic enzymes of anaerobic fungi 总被引:3,自引:2,他引:1
Pectinolytic enzymes of four rumen fungi have been described. Three fungal species were monocentric Neocallimastix spp. H15, JL3 and OC2, and one isolate was a polycentric strain of Orpinomyces joyonii , A4. They differed in degree of pectin degradation and utilization. Only the strain Neocallimastix sp. H15 and partially Orpinomyces joyonii A4 were able to utilize pectin to a higher extent. The most important pectinolytic activity in all these isolates represented pectin lyase (EC 4.2.2.10) and polygalacturonase (EC 3.2.1.15). Their specific activities were in the range of 100–900 and 10–450 μg galacturonic acid h-1 mg protein-1 for pectin lyase and polygalacturonase, respectively. Polygalacturonase, located mainly in the endocellular fraction, was inhibited by calcium ions and had the main pH optimum at pH 6.0. All strains produced pectate lyase (EC 4.2.2.2). None of the strains tested produced pectinesterase (EC 3.1.1.11). 相似文献
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Antitermination of transcription of catabolic operons 总被引:16,自引:2,他引:14
Blanka Rutberg 《Molecular microbiology》1997,23(3):413-321
4.
Ramaiya M Johnson MG Shaw B Heinrichs J Hentschel J von Konrat M Davison PG Shaw AJ 《American journal of botany》2010,97(10):1707-1718
? Premise of the study: The Frullania tamarisci complex includes eight Holarctic liverwort species. One of these, F. asagrayana, is distributed broadly throughout eastern North America from Canada to the Gulf Coast. Preliminary genetic data suggested that the species includes two groups of populations. This study was designed to test whether the two groups are reproductively isolated biological species. ? Methods: Eighty-eight samples from across the range of F. asagrayana, plus 73 samples from one population, were genotyped for 13 microsatellite loci. Sequences for two plastid loci and nrITS were obtained from 13 accessions. Genetic data were analyzed using coalescent models and Bayesian inference. ? Key results: Frullania asagrayana is sequence-invariant at the two plastid loci and ITS2, but two clear groups were resolved by microsatellites. The two groups are largely reproductively isolated, but there is a low level of gene flow from the southern to the northern group. No gene flow was detected in the other direction. A local population was heterogeneous but displayed strong genetic structure. ? Conclusions: The genetic structure of F. asagrayana in eastern North America reflects morphologically cryptic differentiation between reproductively isolated groups of populations, near-panmixis within groups, and clonal propagation at local scales. Reproductive isolation between groups that are invariant at the level of nucleotide sequences shows that caution must be exercised in making taxonomic and evolutionary inferences from reciprocal monophyly (or lack thereof) between putative species. 相似文献
5.
Sequence and length recognition of the C-terminal turnover element of LpxC, a soluble substrate of the membrane-bound FtsH protease 总被引:1,自引:0,他引:1
Führer F Müller A Baumann H Langklotz S Kutscher B Narberhaus F 《Journal of molecular biology》2007,372(2):485-496
The membrane-anchored FtsH protease is essential in Escherichia coli as it adjusts the cellular amount of LpxC, the key enzyme in lipopolysaccharide (LPS) biosynthesis. Both accumulation and depletion of LpxC are toxic to E. coli. By continuous proteolysis of LpxC, FtsH maintains a low concentration of LpxC and, hence, the proper equilibrium between LPS and phospholipids. The C terminus of LpxC is required for turnover. By adding this tail to glutathione-S-transferase (GST) we show that it is necessary but not sufficient for FtsH-mediated degradation. A detailed mutational analysis revealed six non-polar residues in the C terminus of LpxC that are critical for degradation. Alteration of the C-terminal AVLA motif towards the SsrA-like sequence ALAA directed LpxC to other cellular proteases reinforcing the importance of the C-terminal tail for targeting to FtsH. Short C-terminal truncations stabilized LpxC. Most mutations in the C terminus of LpxC left its enzymatic activity intact as was shown by growth assays, microscopy and 2-keto-3-deoxyoctonate (KDO) determination. The critical length of the turnover element was defined by internal deletions. A C-terminal tail of about 20 amino acids length is required for proteolysis of LpxC by FtsH. 相似文献
6.
Dagmar Jičínská Eduard Brabec Marcel Rejmánek Jan Jeník Joří Haager Josef Holub Věroslav Samek Hana Rambousková Josef Holub Marie Naděžda Končalová Robert Neuhäusl Josev Kyncl František Krahuleo Jaroslav Dobrý Blanka Úlehlová Jiří Úlehla Eliška Rybníčková Kamil Rybníček 《Folia Geobotanica》1982,17(4):431-448
7.
Steroidal compounds have been utilized as carriers and for modification of physico-chemical properties of model biologically active secondary alcohols - juvenoids. Juvenoids are juvenile hormone analogues - environmentally safe insecticides, possessing significant biological activity towards different arthropods groups in focus on insect pest species. Structure modification of juvenoids plays important role to control the rate of liberation and decomposition of juvenoid in digestive system and can also play important role in the mode of action towards selected insect. This study presents an approach to the synthesis of steroidal monomers and dimers carrying one and two molecules of a juvenoid in their structures. The prepared compounds were tested for their inhibition activity on reproduction of the blowfly Neobellieria (Sarcophaga) bullata. These steroid-juvenoid conjugates showed promising possibilities in synthesis of new unique biochemical insecticides. Preliminary biological test results of prepared compounds are presented. 相似文献
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9.
Ivan Sebesta Blanka Stiburkova Josef Bartl Kimiyoshi Ichida Makoto Hosoyamada Judy Taylor 《Nucleosides, nucleotides & nucleic acids》2013,32(12):1112-1116
Primary renal hypouricemia is a genetic disorder characterized by defective renal uric acid (UA) reabsorption with complications such as nephrolithiasis and exercise-induced acute renal failure. The known causes are: defects in the SLC22A12 gene, encoding the human urate transporter 1 (hURAT1), and also impairment of voltage urate transporter (URATv1), encoded by SLC2A9 (GLUT9) gene. Diagnosis is based on hypouricemia (<119 μmol/L) and increased fractional excretion of UA (>10%). To date, the cases with mutations in hURAT1 gene have been reported in East Asia only. More than 100 Japanese patients have been described. Hypouricemia is sometimes overlooked; therefore, we have set up the flowchart for this disorder. The patients were selected for molecular analysis from 620 Czech hypouricemic patients. Secondary causes of hyperuricosuric hypouricemia were excluded. The estimations of (1) serum UA, (2) excretion fraction of UA, and (3) analysis of hURAT1 and URATv1 genes follow. Three transitions and one deletion (four times) in SLC22A12 gene and one nucleotide insertion in SLC2A9 gene in seven Czech patients were found. Three patients had acute renal failure and urate nephrolithiasis. In addition, five nonsynonymous sequence variants and three nonsynonymous sequence variants in SLC2A9 gene were found in two UK patients suffering from acute renal failure. Our finding of the defects in SLC22A12 and SLC2A9 genes gives further evidence of the causative genes of primary renal hypouricemia and supports their important role in regulation of serum urate levels in humans. 相似文献
10.
The influence of Mg2+ coordination on 13C and 15N chemical shifts in CKI1RD protein domain from experiment and molecular dynamics/density functional theory calculations 下载免费PDF全文
Martin Babinský Olga Otrusinová Séverine Jansen Blanka Pekárová Lukáš Žídek Markéta L. Munzarová 《Proteins》2016,84(5):686-699
Sequence dependence of 13C and 15N chemical shifts in the receiver domain of CKI1 protein from Arabidopsis thaliana, CKI1RD, and its complexed form, CKI1RD?Mg2+, was studied by means of MD/DFT calculations. MD simulations of a 20–ns production run length were performed. Nine explicitly hydrated structures of increasing complexity were explored, up to a 40‐amino‐acid structure. The size of the model necessary depended on the type of nucleus, the type of amino acid and its sequence neighbors, other spatially close amino acids, and the orientation of amino acid NH groups and their surface/interior position. Using models covering a 10 and a 15 Å environment of Mg2+, a semi‐quantitative agreement has been obtained between experiment and theory for the V67?I73 sequence. The influence of Mg2+ binding was described better by the 15 Å as compared to the 10 Å model. Thirteen chemical shifts were analyzed in terms of the effect of Mg2+ insertion and geometry preparation. The effect of geometry was significant and opposite in sign to the effect of Mg2+ binding. The strongest individual effects were found for 15N of D70, S74, and V68, where the electrostatics dominated; for 13Cβ of D69 and 15N of K76, where the influences were equal, and for 13Cα of F72 and 13Cβ of K76, where the geometry adjustment dominated. A partial correlation between dominant geometry influence and torsion angle shifts upon the coordination has been observed. Proteins 2016; 84:686–699. © 2016 Wiley Periodicals, Inc. 相似文献