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Mutation in a "tesB-like" hydroxyacyl-coenzyme A-specific thioesterase gene causes hyperproduction of extracellular polyhydroxyalkanoates by Alcanivorax borkumensis SK2
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Sabirova JS Ferrer M Lünsdorf H Wray V Kalscheuer R Steinbüchel A Timmis KN Golyshin PN 《Journal of bacteriology》2006,188(24):8452-8459
A novel mutant of the marine oil-degrading bacterium Alcanivorax borkumensis SK2, containing a mini-Tn5 transposon disrupting a "tesB-like" acyl-coenzyme A (CoA) thioesterase gene, was found to hyperproduce polyhydroxyalkanoates (PHA), resulting in the extracellular deposition of this biotechnologically important polymer when grown on alkanes. The tesB-like gene encodes a distinct novel enzyme activity, which acts exclusively on hydroxylated acyl-CoAs and thus represents a hydroxyacyl-CoA-specific thioesterase. Inactivation of this enzyme results in the rechanneling of CoA-activated hydroxylated fatty acids, the cellular intermediates of alkane degradation, towards PHA production. These findings may open up new avenues for the development of simplified biotechnological processes for the production of PHA as a raw material for the production of bioplastics. 相似文献
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Kaiumov AR Sabirova AR Balaban NP Mardanova AM Il'inskaia ON Kostrov SV Sharipova MR 《Molekuliarnaia biologiia》2008,42(1):117-122
The translation initiation site in the extracellular serine subtilisin-like proteinase gene from Bacillus intermedius (aprBi) (AN AY754946) secreting at the stationary growth phase was established. The analysis of aprBi open reading frame revealed three putative translation start sites (TTG, GTG, ATG). Using SignalP online freeware program we have determined the functional activity probability of each of them. To identify the translation start point the modified subtilisin-like protease genes carrying nucleotide replacements in supposed start codons were developed using oligonucleotide-directed mutagenesis. We have investigated the expression of these genetic constructions in protease-deficient strain B. subtilis AJ73. According our results it was concluded that the translation in aprBi gene starts from GTG kodon. 相似文献
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不同的植物对铝胁迫的生理响应不同, 因而对铝毒的耐性也不相同。设置5种铝浓度,进行砂培法处理,研究了4种我国南方红壤广泛分布的草本植物——牵牛(Pharbitis nil)、望江南(Cassia occidentlis)、光头稗(Echinochloa colonum)和合萌(Aeschynomene indica)的种子萌发、光合色素、脯氨酸含量、丙二醛(MDA)含量、可溶性糖(SS)含量、质膜透性(MP)、过氧化氢酶 (CAT) 活性以及过氧化物酶 (POD)活性的变化。结果表明铝对4种植物的生理特性都有明显的影响。4种植物的种子在10 000 mg·L-1 Al3+处理条件下都不能萌发。2 000 mg·L-1 Al3+处理都不利于4种植物的生长,与对照相比,2 000 mg·L-1 Al3+处理时4种草本植物叶绿素和叶绿素总含量显著降低(p<0.05);MDA含量和MP显著增加(p<0.05);脯氨酸含量极显著增加(p<0.01);POD和CAT活性极显著降低(p<0.01)。中低铝(80和400 mg·L-1)处理时,牵牛和合萌与对照相比,MP和MDA含量降低,POD和CAT活性升高;望江南的反应与牵牛和合萌的反应相反;光头稗在80 mg·L-1 Al3+处理时,与牵牛和合萌的变化一致,在400 mg·L-1 Al3+处理时,则相反。植物在中低铝处理条件下,通过维持较高的POD和CAT活性和脯氨酸、叶绿素含量,较低的MP和MDA含量来增加其对铝的耐性。 相似文献
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Inge N.A. Van Bogaert Julia Sabirova Dirk Develter Wim Soetaert & Erick J. Vandamme 《FEMS yeast research》2009,9(4):610-617
The nonpathogenic yeast Candida bombicola synthesizes sophorolipids. These biosurfactants are composed of the disaccharide sophorose linked to a long-chain hydroxy fatty acid and have potential applications in the food, pharmaceutical, cosmetic and cleaning industries. In order to expand the range of application, a shift of the fatty acid moiety towards medium-chain lengths would be recommendable. However, the synthesis of medium-chain sophorolipids by C. bombicola is a challenging objective. First of all, these sophorolipids can only be obtained by fermentations on unconventional carbon sources, which often have a toxic effect on the cells. Furthermore, medium-chain substrates are partially metabolized in the β-oxidation pathway. In order to redirect unconventional substrates towards sophorolipid synthesis, the β-oxidation pathway was blocked on the genome level by knocking out the multifunctional enzyme type 2 (MFE-2) gene. The total gene sequence of the C. bombicola MFE-2 (6033 bp) was cloned (GenBank accession number EU371724 ), and the obtained nucleotide sequence was used to construct a knock-out cassette. Several knock-out mutants with the correct geno- and phenotype were evaluated in a fermentation on 1-dodecanol. All mutants showed a 1.7–2.9 times higher production of sophorolipids, indicating that in those strains the substrate is redirected towards the sophorolipid synthesis. 相似文献
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Extracts of Desulfovibrio desulfuricans B-1388 cells grown under anaerobic conditions displayed superoxide dismutase activity. The maximal activity was found during the stationary growth phase. The enzyme was virtually completely located in the periplasm fraction. D. desulfuricans B-1388 lacked catalase activity but contained active NADH- and NADPH-peroxidases. The activity of NADH-peroxidase depended on the physiological state of the culture. On changing the growth conditions (the presence of 5% CO in the gaseous phase), the activity of superoxide dismutase decreased. 相似文献
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Jascha Vervoort Anna Baraniak Muriel Gazin Julia Sabirova Christine Lammens Meital Kazma Anna Grabowska Rados?aw Izdebski Yehuda Carmeli Samir Kumar-Singh Marek Gniadkowski Herman Goossens Surbhi Malhotra-Kumar 《PloS one》2012,7(9)