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Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger.

Wadman MW, de Vries RP, Kalkhove SI, Veldink GA, Vliegenthart JF - BMC Microbiol. (2009)

Bottom Line: Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.Expression analysis confirmed that all three genes are indeed expressed under the conditions tested.Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development.

View Article: PubMed Central - HTML - PubMed

Affiliation: Bioorganic Chemistry, Utrecht University, 3584 CH, Utrecht, the Netherlands. m.w.wadman@uu.nl

ABSTRACT

Background: Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction 1. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation 234. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.

Results: The current study shows experimentally that A. niger produces the oxylipins 8,11-dihydroxy octadecadienoic acid (8,11-diHOD), 5,8-dihydroxy octadecadienoic acid (5,8-diHOD), lactonized 5,8-diHOD, 8-hydroxy octadecadienoic acid (8-HOD), 10-hydroxy octadecadienoic acid (10-HOD), small amounts of 8-hydroxy octadecamonoenoic acid (8-HOM), 9-hydroxy octadecadienoic acid (9-HOD) and 13-hydroxy octadecadienoic acid (13-HOD). Importantly, this study shows that the A. niger genome contains three putative dioxygenase genes, ppoA, ppoC and ppoD. Expression analysis confirmed that all three genes are indeed expressed under the conditions tested.

Conclusion: A. niger produces the same oxylipins and has similar dioxygenase genes as A. nidulans. Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development.

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Amino acid alignment of the predicted proximal His domain in A. niger PpoA, PpoC and PpoD to A. nidulans PpoA, PpoB and PpoC. Identical amino acids are marked with asterisks; similar amino acids are marked with colons. The proximal His and the Tyr residue important for catalysis in PGS are marked with ○ and ● respectively. Deviating amino acids (Phe instead of Trp, and Gln instead of Lys), in A. niger PpoD are indicated in grey.
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Figure 2: Amino acid alignment of the predicted proximal His domain in A. niger PpoA, PpoC and PpoD to A. nidulans PpoA, PpoB and PpoC. Identical amino acids are marked with asterisks; similar amino acids are marked with colons. The proximal His and the Tyr residue important for catalysis in PGS are marked with ○ and ● respectively. Deviating amino acids (Phe instead of Trp, and Gln instead of Lys), in A. niger PpoD are indicated in grey.

Mentions: In analogy with G. graminis LDS and A. nidulans Ppo's, A. niger PpoA, PpoC and PpoD showed homology to animal PGS (E-values > 7 × 10-21; > 3 × 10-24; > 3 × 10-18, respectively). A. niger PpoA, PpoC and PpoD also contained the distal (202; 246; 265, respectively) and proximal (377; 424; 444, respectively) His, and Tyr (374; 420; 441, respectively) residues, essential for catalytic activity of PGS. Amino acid analysis of the predicted proximal His domain revealed that PpoD differed from the other Aspergillus Ppo's in having a Phe (443) instead of a Trp residue between the proximal His and Tyr residues and that a Lys, conserved in the other Ppo's, was replaced by a Gln (453) residue (Fig. 2)


Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger.

Wadman MW, de Vries RP, Kalkhove SI, Veldink GA, Vliegenthart JF - BMC Microbiol. (2009)

Amino acid alignment of the predicted proximal His domain in A. niger PpoA, PpoC and PpoD to A. nidulans PpoA, PpoB and PpoC. Identical amino acids are marked with asterisks; similar amino acids are marked with colons. The proximal His and the Tyr residue important for catalysis in PGS are marked with ○ and ● respectively. Deviating amino acids (Phe instead of Trp, and Gln instead of Lys), in A. niger PpoD are indicated in grey.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2666749&req=5

Figure 2: Amino acid alignment of the predicted proximal His domain in A. niger PpoA, PpoC and PpoD to A. nidulans PpoA, PpoB and PpoC. Identical amino acids are marked with asterisks; similar amino acids are marked with colons. The proximal His and the Tyr residue important for catalysis in PGS are marked with ○ and ● respectively. Deviating amino acids (Phe instead of Trp, and Gln instead of Lys), in A. niger PpoD are indicated in grey.
Mentions: In analogy with G. graminis LDS and A. nidulans Ppo's, A. niger PpoA, PpoC and PpoD showed homology to animal PGS (E-values > 7 × 10-21; > 3 × 10-24; > 3 × 10-18, respectively). A. niger PpoA, PpoC and PpoD also contained the distal (202; 246; 265, respectively) and proximal (377; 424; 444, respectively) His, and Tyr (374; 420; 441, respectively) residues, essential for catalytic activity of PGS. Amino acid analysis of the predicted proximal His domain revealed that PpoD differed from the other Aspergillus Ppo's in having a Phe (443) instead of a Trp residue between the proximal His and Tyr residues and that a Lys, conserved in the other Ppo's, was replaced by a Gln (453) residue (Fig. 2)

Bottom Line: Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.Expression analysis confirmed that all three genes are indeed expressed under the conditions tested.Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development.

View Article: PubMed Central - HTML - PubMed

Affiliation: Bioorganic Chemistry, Utrecht University, 3584 CH, Utrecht, the Netherlands. m.w.wadman@uu.nl

ABSTRACT

Background: Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction 1. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation 234. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.

Results: The current study shows experimentally that A. niger produces the oxylipins 8,11-dihydroxy octadecadienoic acid (8,11-diHOD), 5,8-dihydroxy octadecadienoic acid (5,8-diHOD), lactonized 5,8-diHOD, 8-hydroxy octadecadienoic acid (8-HOD), 10-hydroxy octadecadienoic acid (10-HOD), small amounts of 8-hydroxy octadecamonoenoic acid (8-HOM), 9-hydroxy octadecadienoic acid (9-HOD) and 13-hydroxy octadecadienoic acid (13-HOD). Importantly, this study shows that the A. niger genome contains three putative dioxygenase genes, ppoA, ppoC and ppoD. Expression analysis confirmed that all three genes are indeed expressed under the conditions tested.

Conclusion: A. niger produces the same oxylipins and has similar dioxygenase genes as A. nidulans. Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development.

Show MeSH