Biology subjects

Martzoukou, O.

Publications and source records attributed to Martzoukou, O..

4 recordsLinked to original sources

bioRxiv2022

The interplay between sulfur assimilation and biodesulfurization phenotype in Rhodococcus qingshengii IGTS8: Insights into a regulatory role of the reverse transsulfuration pathway

Biodesulfurization (BDS) is a process that selectively removes sulfur from dibenzothiophene and its derivatives. Several mesophilic natural biocatalysts have been isolated, harboring the highly conserved desulfurization operon dszABC. Even though the desulfurization phenotype is known to be significantly repressed by methionine, cysteine, and inorganic sulfate, the available information on the metabolic regulation of gene expression is still limited. In this study, scarless knockouts of the sulfur metabolism-related cbs and metB genes are constructed in the desulfurizing strain Rhodococcus sp. IGTS8. We provide sequence analyses for both enzymes of the reverse transsulfuration pathway and report their involvement in the sulfate- and methionine-dependent repression of the biodesulfurization phenotype, based on desulfurization assays in the presence of different sulfur sources. Additionally, the positive effect of cbs and metB gene deletions on dsz gene expression in the presence of both sulfate and methionine, but not cysteine, is uncovered and highlighted.

microbiology↗

bioRxiv2022

The interplay between sulfur metabolism and desulfurization profile in Rhodococcus: Unraveling the role of the transsulfuration pathway

Biodesulfurization (BDS) is a process that selectively removes sulfur from dibenzothiophene and its derivatives. Several natural biocatalysts have been isolated, all harboring the highly conserved desulfurization operon dszABC. Even though the desulfurization phenotype is known to be significantly repressed by methionine, cysteine, and inorganic sulfate, the available information on the metabolic regulation of gene expression is still limited. In this study, scarless knockouts of the sulfur metabolism-related cbs and metB genes are constructed in the desulfurizing strain Rhodococcus sp. IGTS8. We provide sequence analyses for both enzymes of the reverse transsulfuration pathway and report their involvement in the sulfate- and methionine-dependent repression of the biodesulfurization phenotype, based on desulfurization assays in the presence of different sulfur sources. Additionally, the positive effect of cbs and metB gene deletions on dsz gene expression in the presence of both sulfate and methionine, but not cysteine, is uncovered and highlighted.

microbiology↗

bioRxiv2019

Nutrient transporter translocation to the plasma membrane via a Golgi-independent unconventional route

Nutrient transporters are believed to traffic from their site of synthesis, the ER, to the plasma membrane, through the Golgi, using the conventional vesicular trafficking pathway. However, here we report that the UapA purine transporter in Aspergillus nidulans, follows a Golgi-independent, unconventional new route, which does not involve key Rab GTPases, AP adaptors, microtubules or endosomes, but is dependent on functional COPII, clathrin heavy chain (ClaH) and actin. The role of ClaH in transporter secretion is shown to be unrelated to that performing, together with Rab11/AP-1, at the Golgi, and is seemingly due to an effect in actin network functioning. Our findings are discussed within the frame of a model that rationalizes why the trafficking mechanism uncovered herein might hold true for transporters in higher organisms. One Sentence SummaryFungal transporters use a non-polar, COPII- and actin-dependent, route for subcellular traffic to the cell membrane.

cell biology↗

bioRxiv2018

The AP-1 complex is essential for fungal growth via its role in secretory vesicle polar sorting, endosomal recycling and cytoskeleton organization

The AP-1 complex is essential for membrane protein traffic via its role in the pinching-off and sorting of secretory vesicles from the trans-Golgi and/or endosomes. While its essentiality is undisputed in metazoa, its role in model simpler eukaryotes seems less clear. Here we dissect the role of AP-1 in the filamentous fungus Aspergillus nidulans and show that it is absolutely essential for growth due to its role in clathrin-dependent maintenance of polar traffic of specific membrane cargoes towards the apex of growing hyphae. We provide evidence that AP-1 is involved in both anterograde sorting of RabERab11-labeled secretory vesicles and RabA/BRab5- dependent endosome recycling. Additionally, AP-1 is shown to be critical for microtubule and septin organization, further rationalizing its essentiality in cells that face the challenge of cytoskeleton-dependent polarized cargo traffic. This work also opens a novel issue on how non-polar cargoes, such as transporters, are sorted to the eukaryotic plasma membrane.

cell biology↗