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Polyketides, toxins and pigments in Penicillium marneffei.

Tam EW, Tsang CC, Lau SK, Woo PC - Toxins (Basel) (2015)

Bottom Line: This number is much higher than those of Coccidioides immitis and Histoplasma capsulatum, important pathogenic thermally dimorphic fungi in the Western world.Phylogenetically, these polyketide synthase genes were distributed evenly with their counterparts found in Aspergillus species and other fungi, suggesting that polyketide synthases in P. marneffei did not diverge from lineage-specific gene duplication through a recent expansion.Gene knockdown experiments and ultra-high performance liquid chromatography-photodiode array detector/electrospray ionization-quadruple time of flight-mass spectrometry analysis confirmed that at least four of the polyketide synthase genes were involved in the biosynthesis of various pigments in P. marneffei, including melanin, mitorubrinic acid, mitorubrinol, monascorubrin, rubropunctatin, citrinin and ankaflavin, some of which were mycotoxins and virulence factors of the fungus.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong. emily.wt@gmail.com.

ABSTRACT
Penicillium marneffei (synonym: Talaromyces marneffei) is the most important pathogenic thermally dimorphic fungus in China and Southeastern Asia. The HIV/AIDS pandemic, particularly in China and other Southeast Asian countries, has led to the emergence of P. marneffei infection as an important AIDS-defining condition. Recently, we published the genome sequence of P. marneffei. In the P. marneffei genome, 23 polyketide synthase genes and two polyketide synthase-non-ribosomal peptide synthase hybrid genes were identified. This number is much higher than those of Coccidioides immitis and Histoplasma capsulatum, important pathogenic thermally dimorphic fungi in the Western world. Phylogenetically, these polyketide synthase genes were distributed evenly with their counterparts found in Aspergillus species and other fungi, suggesting that polyketide synthases in P. marneffei did not diverge from lineage-specific gene duplication through a recent expansion. Gene knockdown experiments and ultra-high performance liquid chromatography-photodiode array detector/electrospray ionization-quadruple time of flight-mass spectrometry analysis confirmed that at least four of the polyketide synthase genes were involved in the biosynthesis of various pigments in P. marneffei, including melanin, mitorubrinic acid, mitorubrinol, monascorubrin, rubropunctatin, citrinin and ankaflavin, some of which were mycotoxins and virulence factors of the fungus.

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Phylogenetic tree showing the relationship of the polyketide synthases (PKSs) of Penicillium marneffei with other organisms, inferred from the partial ketosynthase domain amino acid sequence data by the maximum likelihood method using the substitution model WAG (Whelan and Goldman model) + F (estimated of amino acid frequency) + G (gamma-distributed rate variation) + I (estimated proportion of invariable sites). The scale bar indicates the estimated number of substitutions per amino acid residue. All names and accession numbers are given as cited in the DDBJ/ENA/GenBank databases. Numbers at nodes indicate levels of bootstrap support calculated from 1 000 trees and are expressed as percentage. Only nodes that were well supported by the maximum likelihood method (≥70% bootstrap support) have their bootstrap values shown. Clades and the typical domain organization defined by Kroken et al. [22] are indicated. The 21 putative PKSs of P. marneffei which contained all the KS, AT, and ACP domains were highlighted in red color. A. adenylation; ACP, acyl carrier protein; AT, acyltransferase; C, condensation; DH, dehydrogenase; ER, enylreductase; KR, ketoreductase; KS, ketosynthase; MT, methyltransferase; T, thiolation; TE, thioesterase; and R, reductase. Adapted with permission from “Phylogenetic analysis of PKSs of Penicillium marneffei” in “Characterization of polyketide synthases in Penicillium marneffei” by W. T. Tam, 2012, PhD thesis submitted to the University of Hong Kong, p.93. Copyright 2012 licensed under Creative Commons: Attribution 3.0 Hong Kong License (https://creativecommons.org/licenses/by/3.0/hk/).
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toxins-07-04421-f001: Phylogenetic tree showing the relationship of the polyketide synthases (PKSs) of Penicillium marneffei with other organisms, inferred from the partial ketosynthase domain amino acid sequence data by the maximum likelihood method using the substitution model WAG (Whelan and Goldman model) + F (estimated of amino acid frequency) + G (gamma-distributed rate variation) + I (estimated proportion of invariable sites). The scale bar indicates the estimated number of substitutions per amino acid residue. All names and accession numbers are given as cited in the DDBJ/ENA/GenBank databases. Numbers at nodes indicate levels of bootstrap support calculated from 1 000 trees and are expressed as percentage. Only nodes that were well supported by the maximum likelihood method (≥70% bootstrap support) have their bootstrap values shown. Clades and the typical domain organization defined by Kroken et al. [22] are indicated. The 21 putative PKSs of P. marneffei which contained all the KS, AT, and ACP domains were highlighted in red color. A. adenylation; ACP, acyl carrier protein; AT, acyltransferase; C, condensation; DH, dehydrogenase; ER, enylreductase; KR, ketoreductase; KS, ketosynthase; MT, methyltransferase; T, thiolation; TE, thioesterase; and R, reductase. Adapted with permission from “Phylogenetic analysis of PKSs of Penicillium marneffei” in “Characterization of polyketide synthases in Penicillium marneffei” by W. T. Tam, 2012, PhD thesis submitted to the University of Hong Kong, p.93. Copyright 2012 licensed under Creative Commons: Attribution 3.0 Hong Kong License (https://creativecommons.org/licenses/by/3.0/hk/).

Mentions: A total of 25 pks genes have been identified in the draft genome of P. marneffei [18]. For those fungi with available genome sequences, there are only: one pks gene in H. capsulatum, ten in C. immitis, 14 in Aspergillus fumigatus, 16 in Gibberalla zeae, 20 in P. chrysogenum, 27 in A. nidulans, and 30 in A. oryzae [19]. Although the diversity of pks genes in the genome of P. marneffei is similar to phylogenetically closely related fungi, such as Aspergillus species, the pks genes of P. marneffei are much more diverse than those of other thermally dimorphic fungi. This implies that P. marneffei could potentially produce a larger variety of polyketide metabolites than other clinically important thermally dimorphic fungi [18]. When the gene sequences of the PKS domains of Aspergillus spp. were used to BLAST against the P. marneffei genome in the GenBank database, it was found that 23 putative pks genes and two putative PKS-non-ribosomal peptide synthase (NRPS) hybrid genes (pks-nrps2 and pks-nrps8) are present in the genome of P. marneffei [18,20,21]. Among the 23 gene candidates, 21 putative pks genes encode gene products with the ketosynthase (KS), acyltransferase (AT) and acyl carrier protein (ACP) domains, which are the constitutional components of PKS. The ACP domain is absent in the predicted gene products of the remaining two candidates (pks13 and pks25), implying that these two genes might be pseudogenes [18]. The 21 putative pks genes with the KS, AT and ACP domains are clustered in 18 groups, where three of these groups contain two pks genes each (pks11 and pks12, pks16 and pks17, and pks20 and pks21). These 18 groups of putative pks genes could potentially produce 18 different polyketide metabolites. Twelve of these 21 gene candidates belong to the non-reducing type, whereas the remaining nine belong to the reducing type, which, on top of the KS, AT and ACP domains, also contain the dehydrogenase (DH) and ketoreductase (KR) domains [18] (Figure 1). Eight of the nine pks genes belonging to the reducing type possess the enoylreductase (ER) domain. For the three gene clusters in the genome which contain two pks genes each, two clusters (pks16 and pks17, and pks20 and pks21) encode one non-reducing and one reducing PKS, and the third cluster (pks11 and pks12) encodes two reducing PKSs. As for the two pks-nrps hybrid candidate genes (pks-nrps2 and pks-nrps8), the PKS modules belong to the reducing type with DH and KR domains, and the whole NRPS modules possess the condensation (C), adenylation (A), thiolation (T) and thiolester reductase (R) domains [18].


Polyketides, toxins and pigments in Penicillium marneffei.

Tam EW, Tsang CC, Lau SK, Woo PC - Toxins (Basel) (2015)

Phylogenetic tree showing the relationship of the polyketide synthases (PKSs) of Penicillium marneffei with other organisms, inferred from the partial ketosynthase domain amino acid sequence data by the maximum likelihood method using the substitution model WAG (Whelan and Goldman model) + F (estimated of amino acid frequency) + G (gamma-distributed rate variation) + I (estimated proportion of invariable sites). The scale bar indicates the estimated number of substitutions per amino acid residue. All names and accession numbers are given as cited in the DDBJ/ENA/GenBank databases. Numbers at nodes indicate levels of bootstrap support calculated from 1 000 trees and are expressed as percentage. Only nodes that were well supported by the maximum likelihood method (≥70% bootstrap support) have their bootstrap values shown. Clades and the typical domain organization defined by Kroken et al. [22] are indicated. The 21 putative PKSs of P. marneffei which contained all the KS, AT, and ACP domains were highlighted in red color. A. adenylation; ACP, acyl carrier protein; AT, acyltransferase; C, condensation; DH, dehydrogenase; ER, enylreductase; KR, ketoreductase; KS, ketosynthase; MT, methyltransferase; T, thiolation; TE, thioesterase; and R, reductase. Adapted with permission from “Phylogenetic analysis of PKSs of Penicillium marneffei” in “Characterization of polyketide synthases in Penicillium marneffei” by W. T. Tam, 2012, PhD thesis submitted to the University of Hong Kong, p.93. Copyright 2012 licensed under Creative Commons: Attribution 3.0 Hong Kong License (https://creativecommons.org/licenses/by/3.0/hk/).
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Related In: Results  -  Collection

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toxins-07-04421-f001: Phylogenetic tree showing the relationship of the polyketide synthases (PKSs) of Penicillium marneffei with other organisms, inferred from the partial ketosynthase domain amino acid sequence data by the maximum likelihood method using the substitution model WAG (Whelan and Goldman model) + F (estimated of amino acid frequency) + G (gamma-distributed rate variation) + I (estimated proportion of invariable sites). The scale bar indicates the estimated number of substitutions per amino acid residue. All names and accession numbers are given as cited in the DDBJ/ENA/GenBank databases. Numbers at nodes indicate levels of bootstrap support calculated from 1 000 trees and are expressed as percentage. Only nodes that were well supported by the maximum likelihood method (≥70% bootstrap support) have their bootstrap values shown. Clades and the typical domain organization defined by Kroken et al. [22] are indicated. The 21 putative PKSs of P. marneffei which contained all the KS, AT, and ACP domains were highlighted in red color. A. adenylation; ACP, acyl carrier protein; AT, acyltransferase; C, condensation; DH, dehydrogenase; ER, enylreductase; KR, ketoreductase; KS, ketosynthase; MT, methyltransferase; T, thiolation; TE, thioesterase; and R, reductase. Adapted with permission from “Phylogenetic analysis of PKSs of Penicillium marneffei” in “Characterization of polyketide synthases in Penicillium marneffei” by W. T. Tam, 2012, PhD thesis submitted to the University of Hong Kong, p.93. Copyright 2012 licensed under Creative Commons: Attribution 3.0 Hong Kong License (https://creativecommons.org/licenses/by/3.0/hk/).
Mentions: A total of 25 pks genes have been identified in the draft genome of P. marneffei [18]. For those fungi with available genome sequences, there are only: one pks gene in H. capsulatum, ten in C. immitis, 14 in Aspergillus fumigatus, 16 in Gibberalla zeae, 20 in P. chrysogenum, 27 in A. nidulans, and 30 in A. oryzae [19]. Although the diversity of pks genes in the genome of P. marneffei is similar to phylogenetically closely related fungi, such as Aspergillus species, the pks genes of P. marneffei are much more diverse than those of other thermally dimorphic fungi. This implies that P. marneffei could potentially produce a larger variety of polyketide metabolites than other clinically important thermally dimorphic fungi [18]. When the gene sequences of the PKS domains of Aspergillus spp. were used to BLAST against the P. marneffei genome in the GenBank database, it was found that 23 putative pks genes and two putative PKS-non-ribosomal peptide synthase (NRPS) hybrid genes (pks-nrps2 and pks-nrps8) are present in the genome of P. marneffei [18,20,21]. Among the 23 gene candidates, 21 putative pks genes encode gene products with the ketosynthase (KS), acyltransferase (AT) and acyl carrier protein (ACP) domains, which are the constitutional components of PKS. The ACP domain is absent in the predicted gene products of the remaining two candidates (pks13 and pks25), implying that these two genes might be pseudogenes [18]. The 21 putative pks genes with the KS, AT and ACP domains are clustered in 18 groups, where three of these groups contain two pks genes each (pks11 and pks12, pks16 and pks17, and pks20 and pks21). These 18 groups of putative pks genes could potentially produce 18 different polyketide metabolites. Twelve of these 21 gene candidates belong to the non-reducing type, whereas the remaining nine belong to the reducing type, which, on top of the KS, AT and ACP domains, also contain the dehydrogenase (DH) and ketoreductase (KR) domains [18] (Figure 1). Eight of the nine pks genes belonging to the reducing type possess the enoylreductase (ER) domain. For the three gene clusters in the genome which contain two pks genes each, two clusters (pks16 and pks17, and pks20 and pks21) encode one non-reducing and one reducing PKS, and the third cluster (pks11 and pks12) encodes two reducing PKSs. As for the two pks-nrps hybrid candidate genes (pks-nrps2 and pks-nrps8), the PKS modules belong to the reducing type with DH and KR domains, and the whole NRPS modules possess the condensation (C), adenylation (A), thiolation (T) and thiolester reductase (R) domains [18].

Bottom Line: This number is much higher than those of Coccidioides immitis and Histoplasma capsulatum, important pathogenic thermally dimorphic fungi in the Western world.Phylogenetically, these polyketide synthase genes were distributed evenly with their counterparts found in Aspergillus species and other fungi, suggesting that polyketide synthases in P. marneffei did not diverge from lineage-specific gene duplication through a recent expansion.Gene knockdown experiments and ultra-high performance liquid chromatography-photodiode array detector/electrospray ionization-quadruple time of flight-mass spectrometry analysis confirmed that at least four of the polyketide synthase genes were involved in the biosynthesis of various pigments in P. marneffei, including melanin, mitorubrinic acid, mitorubrinol, monascorubrin, rubropunctatin, citrinin and ankaflavin, some of which were mycotoxins and virulence factors of the fungus.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong. emily.wt@gmail.com.

ABSTRACT
Penicillium marneffei (synonym: Talaromyces marneffei) is the most important pathogenic thermally dimorphic fungus in China and Southeastern Asia. The HIV/AIDS pandemic, particularly in China and other Southeast Asian countries, has led to the emergence of P. marneffei infection as an important AIDS-defining condition. Recently, we published the genome sequence of P. marneffei. In the P. marneffei genome, 23 polyketide synthase genes and two polyketide synthase-non-ribosomal peptide synthase hybrid genes were identified. This number is much higher than those of Coccidioides immitis and Histoplasma capsulatum, important pathogenic thermally dimorphic fungi in the Western world. Phylogenetically, these polyketide synthase genes were distributed evenly with their counterparts found in Aspergillus species and other fungi, suggesting that polyketide synthases in P. marneffei did not diverge from lineage-specific gene duplication through a recent expansion. Gene knockdown experiments and ultra-high performance liquid chromatography-photodiode array detector/electrospray ionization-quadruple time of flight-mass spectrometry analysis confirmed that at least four of the polyketide synthase genes were involved in the biosynthesis of various pigments in P. marneffei, including melanin, mitorubrinic acid, mitorubrinol, monascorubrin, rubropunctatin, citrinin and ankaflavin, some of which were mycotoxins and virulence factors of the fungus.

Show MeSH
Related in: MedlinePlus