欧美日韩Aa在线直播_自拍青草99视频_日本一线产区和韩国二线_日韩.国产.噢美日韩精品综合观看_亚州四虎精品久久久_曰曰日在线_精品久久久av_精品欧美国产一区二区三区不卡_欧美亚洲日韩_天天ri网_国产精品看片直播_亚洲中文久久久久久精品国产_天天色天天日综合_久久久久久成人免费看A四叶草_丁香六月狠狠综合天香_永久的伊甸园_国产熟妇无码A片AAA毛片视频

當(dāng)前位置: 首頁(yè) >> 產(chǎn)業(yè)發(fā)展 >> 正文

Recent advances in understanding PHA degradation

時(shí)間:2004-10-27
關(guān)鍵詞:Recent advances understanding PHA degradation 來(lái)源:International Symposium on Biological Polyesters ,Auguest 22-27, 2004

 

D. Jendrossek, R. Handrick, and S. Reinhardt

 

Institut für Mikrobiologie der Universität Stuttart, Germany

 

PHB depolymerases can be distinguished by their substrate specificity for native (amorphous) PHB (nPHB; nPHB depolymerases) or for denatured (partially crystalline) PHB (dPHB; dPHB depolymerases. Many extracellular dPHA depolymerases (EC 3.1.1.75 and 3.1.1.76) have been characterized on the molecular level during the last decade but little is known about (intracellular) nPHA depolymerases. In was only until recently that up to 5 genes coding for putative intracellular nPHB depolymerases were found in Wautersia eutropha H16 (formerly Ralstonia eutropha). Intracellular nPHB depolymerases are not related to extracellular dPHB depolymerases with respect to amino acid sequence but share significant amino acid similarities between each other.

In this contribution we investigated nPHB depolymerases of W. eutropha and of Rhodospirillum rubrum. Both bacteria do not have any detectable extracellular PHB depolymerase activity. Fusions of selected depolymerase genes with variant genes of the green fluorescent protein (EGFP) were constructed and expression and localization of the depolymerases were followed fluorescence-microscopically. PhaZ1-EGFP was expressed in wild type H16 and in a phaZ1 deletion mutant during PHB accumulation phase and during starvation, i.e. PHB mobilization phase. Fluorescence microscopical analysis revealed that PhaZ1-EGFP colocalized with PHB granules. Our results confirmed earlier observations that PHB accumulation and PHB mobilization can occur simultaneously.

An unexpected and surprising result was obtained for putative intracellular PHB depolymerase of R. rubrum: PHB depolymerase PhaZ1 was located in the periplasm. Moreover, its amino acid sequence was unrelated to intracellular PHB depolymerases of W. eutropha but was significantly related to extracellular dPHB depolymerases. A second gene, phaZ2, was found in the R. rubrum genome that apparently encoded the true intracellular PHB depolymerase.

 

論文來(lái)源:International Symposium on Biological Polyesters ,Auguest 22-27, 2004