Q30DW5 · PKSA_DOTSE
- ProteinNorsolorinic acid synthase
- GenepksA
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids2399 (go to sequence)
- Protein existenceEvidence at transcript level
- Annotation score4/5
Function
function
Polyketide synthase; part of the fragmented gene cluster that mediates the biosynthesis of dothistromin (DOTH), a polyketide toxin very similar in structure to the aflatoxin precursor, versicolorin B (PubMed:12039746, PubMed:17683963, PubMed:22069571, PubMed:23207690, PubMed:23448391).
The first step of the pathway is the conversion of acetate to norsolorinic acid (NOR) and requires the fatty acid synthase subunits hexA and hexB, as well as the polyketide synthase pksA (PubMed:16649078, PubMed:23207690).
PksA combines a hexanoyl starter unit and 7 malonyl-CoA extender units to synthesize the precursor NOR (By similarity).
The hexanoyl starter unit is provided to the acyl-carrier protein (ACP) domain by the fungal fatty acid synthase hexA/hexB (By similarity).
The second step is the conversion of NOR to averantin (AVN) and requires the norsolorinic acid ketoreductase nor1, which catalyzes the dehydration of norsolorinic acid to form (1'S)-averantin (PubMed:23207690).
The cytochrome P450 monooxygenase avnA then catalyzes the hydroxylation of AVN to 5'hydroxyaverantin (HAVN) (PubMed:23207690).
The next step is performed by adhA that transforms HAVN to averufin (AVF) (PubMed:23207690).
Averufin might then be converted to hydroxyversicolorone by cypX and avfA (PubMed:23207690).
Hydroxyversicolorone is further converted versiconal hemiacetal acetate (VHA) by moxY (PubMed:23207690).
VHA is then the substrate for the versiconal hemiacetal acetate esterase est1 to yield versiconal (VAL) (PubMed:23207690).
Versicolorin B synthase vbsA then converts VAL to versicolorin B (VERB) by closing the bisfuran ring (PubMed:16649078, PubMed:23207690).
Then, the activity of the versicolorin B desaturase verB leads to versicolorin A (VERA) (PubMed:23207690).
DotB, a predicted chloroperoxidase, may perform epoxidation of the A-ring of VERA (PubMed:23207690).
Alternatively, a cytochrome P450, such as cypX or avnA could catalyze this step (PubMed:23207690).
It is also possible that another, uncharacterized, cytochrome P450 enzyme is responsible for this step (PubMed:23207690).
Opening of the epoxide could potentially be achieved by the epoxide hydrolase epoA (PubMed:23207690).
However, epoA seems not to be required for DOTH biosynthesis, but other epoxide hydrolases may have the ability to complement this hydrolysis (PubMed:23207690).
Alternatively, opening of the epoxide ring could be achieved non-enzymatically (PubMed:23207690).
The next step is the deoxygenation of ring A to yield the 5,8-dihydroxyanthraquinone which is most likely catalyzed by the NADPH dehydrogenase encoded by ver1 (PubMed:23207690).
The last stages of DOTH biosynthesis are proposed to involve hydroxylation of the bisfuran (PubMed:23207690).
OrdB and norB might have oxidative roles here (PubMed:23207690).
An alternative possibility is that cytochrome P450 monoogenases such as avnA and cypX might perform these steps in addition to previously proposed steps (PubMed:23207690).
The first step of the pathway is the conversion of acetate to norsolorinic acid (NOR) and requires the fatty acid synthase subunits hexA and hexB, as well as the polyketide synthase pksA (PubMed:16649078, PubMed:23207690).
PksA combines a hexanoyl starter unit and 7 malonyl-CoA extender units to synthesize the precursor NOR (By similarity).
The hexanoyl starter unit is provided to the acyl-carrier protein (ACP) domain by the fungal fatty acid synthase hexA/hexB (By similarity).
The second step is the conversion of NOR to averantin (AVN) and requires the norsolorinic acid ketoreductase nor1, which catalyzes the dehydration of norsolorinic acid to form (1'S)-averantin (PubMed:23207690).
The cytochrome P450 monooxygenase avnA then catalyzes the hydroxylation of AVN to 5'hydroxyaverantin (HAVN) (PubMed:23207690).
The next step is performed by adhA that transforms HAVN to averufin (AVF) (PubMed:23207690).
Averufin might then be converted to hydroxyversicolorone by cypX and avfA (PubMed:23207690).
Hydroxyversicolorone is further converted versiconal hemiacetal acetate (VHA) by moxY (PubMed:23207690).
VHA is then the substrate for the versiconal hemiacetal acetate esterase est1 to yield versiconal (VAL) (PubMed:23207690).
Versicolorin B synthase vbsA then converts VAL to versicolorin B (VERB) by closing the bisfuran ring (PubMed:16649078, PubMed:23207690).
Then, the activity of the versicolorin B desaturase verB leads to versicolorin A (VERA) (PubMed:23207690).
DotB, a predicted chloroperoxidase, may perform epoxidation of the A-ring of VERA (PubMed:23207690).
Alternatively, a cytochrome P450, such as cypX or avnA could catalyze this step (PubMed:23207690).
It is also possible that another, uncharacterized, cytochrome P450 enzyme is responsible for this step (PubMed:23207690).
Opening of the epoxide could potentially be achieved by the epoxide hydrolase epoA (PubMed:23207690).
However, epoA seems not to be required for DOTH biosynthesis, but other epoxide hydrolases may have the ability to complement this hydrolysis (PubMed:23207690).
Alternatively, opening of the epoxide ring could be achieved non-enzymatically (PubMed:23207690).
The next step is the deoxygenation of ring A to yield the 5,8-dihydroxyanthraquinone which is most likely catalyzed by the NADPH dehydrogenase encoded by ver1 (PubMed:23207690).
The last stages of DOTH biosynthesis are proposed to involve hydroxylation of the bisfuran (PubMed:23207690).
OrdB and norB might have oxidative roles here (PubMed:23207690).
An alternative possibility is that cytochrome P450 monoogenases such as avnA and cypX might perform these steps in addition to previously proposed steps (PubMed:23207690).
Catalytic activity
- 6 H+ + hexanoyl-[ACP] + 7 malonyl-CoA = 7 CO2 + 7 CoA + 2 H2O + holo-[ACP] + noranthrone
6 CHEBI:15378 + RHEA-COMP:9632 + 7 CHEBI:57384 = 7 CHEBI:16526 + 7 CHEBI:57287 + 2 CHEBI:15377 + RHEA-COMP:9685 + CHEBI:77904
Cofactor
Note: Binds 1 phosphopantetheine covalently.
Pathway
Mycotoxin biosynthesis.
Features
Showing features for active site.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Active site | 544 | For beta-ketoacyl synthase activity | ||||
Sequence: C | ||||||
Active site | 679 | For beta-ketoacyl synthase activity | ||||
Sequence: H | ||||||
Active site | 722 | For beta-ketoacyl synthase activity | ||||
Sequence: H | ||||||
Active site | 995 | For acyl/malonyl transferase activity | ||||
Sequence: S | ||||||
Active site | 1372 | Proton acceptor; for dehydratase activity | ||||
Sequence: H | ||||||
Active site | 1570 | Proton donor; for dehydratase activity | ||||
Sequence: D | ||||||
Active site | 2234 | For thioesterase activity | ||||
Sequence: S |
GO annotations
Aspect | Term | |
---|---|---|
Molecular Function | fatty acid synthase activity | |
Molecular Function | norsolorinate anthrone synthase activity | |
Molecular Function | phosphopantetheine binding | |
Biological Process | fatty acid biosynthetic process | |
Biological Process | toxin biosynthetic process |
Keywords
- Molecular function
Enzyme and pathway databases
Protein family/group databases
Names & Taxonomy
Protein names
- Recommended nameNorsolorinic acid synthase
- EC number
- Short namesNSAS
- Alternative names
Gene names
Organism names
- Strains
- Taxonomic lineageEukaryota > Fungi > Dikarya > Ascomycota > Pezizomycotina > Dothideomycetes > Dothideomycetidae > Mycosphaerellales > Mycosphaerellaceae > Dothistroma
Accessions
- Primary accessionQ30DW5
Phenotypes & Variants
Disruption phenotype
Impairs the production of dothistromin but still enables the conversion of exogenous aflatoxin precursors, including norsolorinic acid, into dothistromin (PubMed:16649078).
PTM/Processing
Features
Showing features for chain, modified residue.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000443456 | 1-2399 | Norsolorinic acid synthase | |||
Sequence: MTHSNATRVLVFGDQTYDFVPKLRELFHVKDNPILTAFLEQSHYVVRAQMIQTLPPAEHKAARTFDLADMLKKYVAGKLNPAFQTALSCITQLGVFMREFHDFTKPYPRHDSSYVLGICTGSLAAAAVSSSNSLSELLPIAVQTALIAFRLGLCVTDMRDRLESSEEDRTQPWSVVLFDTDEQTVTKAIKDFCTSNVLPKTKQPWITSASSKTITISGAPRVLKKLSQEPALKDKKTRQIPIYVPAHNSALFTPEDVKSILETTPVDTWSNYPTKLPFISSVSGKMAWADNYLAVIHLALNQCLLESIGWGKVETELPRLLKSRGAENVLITPITTSADRALSAALSPTISNIEVEKPTINESFAHRPGSGKSKLAIVSMSGRFPEAQSTDAFWDLLYKGLDVVKEVPKRRWDVETHVDPTGRARNKGATKWGCWLDFAGEFDPRFFSISPKEAPQMDPAQRMALMSTWEAMERGGIVPDTTPSTQRNRIGVFHGVTSNDWMETNTAQNIDTYFITGGNRGFIPGRINFCFEFSGPSFTNDTACSSSLAAIHLACNSLWRGDCDTAVAGGTNMIFTPDGHAGLDKGFFLSRTGNCKPFDDKADGYCRAEGVGTVMVKRLEDALADGDPILGTILDAKTNHSAMSDSMTRPFVPAQIDNMEACLSTAGVDPTSLDYIEMHGTGTQVGDAVEMESVLSVFAPNEQFRGKDQPLYVGSAKANIGHGEGVSGVTSLIKVLLMMQNNTIPPHCGIKPGSKINHNYPDLAARNVHIAFEPKPFLRREGKLRRVLINNFSAAGGNTALLIEDAPDRMPLSGQDPRTTQTVTISGHVGKSLSNNVANLLAHLKKNPTIDLSQLAYTVSARRWHHLHRVAVAGTTVADITAKLEKAIENKEGVNRPKAKPSVFFAFTGQGSQYLGMGKQLYDSYPMFRSELQGYDRLAQSQGFPSFAHIFTETKGDVEQNLPVVVQLAITCLQMALFNLVTSFGIKASAVVGHSLGEYAALYAAGVLSASDTIYLVGKRAELLQDHCQRGTHAMLACKASEWSLAEITAGKNVEVACVNGPEDTVLSGTVEEIGEVQKTLSAKSIKATLLKLPFAFHSAQVQPILEDFEELAAGATFEKPKLAVISPLLGSVVEDEGVVGPNYLARHCREAVGMVKALGVAKEKGIINEKTIVIEIGPKPLLCGMIKNILGQNIVALPTLKDKGPDVWQNLSNIFTTLYTGGLDINWTAFHAPFEPAKKVLQLPDYGWDLKDYFIQYEGDWVLHRHKIHCNCADAGKDVHNTSHYCPGKHTFAENVVVPGGAQKAVQEAPAAKTETKKMSKLDPTKEAYPGIPLTTTVHKVIEEKTEPLGAQFTVETDISRKDVNSIAQGHTVDSIPLCTPSFYADIALQVGKYAMDRIRAGHPGAGAIDGRVDVTDLVVDKALIPHGKAPQLLRTNVTMSWPPKMAATTRSAKVTFKTYTADGKLDTDHAYCTVRFTTDSQQKSLQKKVPEYKAAIAKLRARDAKGELTHYNTKSGYKLMSSMAHFHPDYKLLDNLVLNEAENEAVSVMNFSSCTDAGIYAAHPAYVDAITQVGGFAMNAKDDTDIDKEVYVNHGWESFQVYKKMEKSVEYVVYSKMTKDPKGDMVHGDTIVLDGDEVVAFFRGLSLRSVPRKALRAVLQSAMDKGIRQRGGKPGAAKGAVAAPAPAKKMVEPVKAASKKETPAAAAPPSPSKAAPPPAPKPAALKASVPKADPGKVDEALKIISEESGIALDELTDDSNFTDMGVDSLSSMVITSRLREDLELDLAPDFALFADCPTVASLRTFLAGAAGGPTDSPAAIATLEFGEPTPAKELEAGPALKSTPISPGVQALQPVPAPTPAPKPVITSPAAPVSSKVFDDALQIISEESGIALDELTDDSNFTDMGVDSLSSMVITSRLREDLELDLSPDWALFADCPTVASLRSFLGGSGPGSTAPADADTPVDTTAAEIEAPVPNEAASYMPNSSQADVDDAVAAVIGNDPPRRPEPPKQAAAPAVARTEALNAALDIIAEESGVAAEDFTDDTIFSDIGIDSLCSMVISSRFREELELDLDSQFSLFVDLPTVAQLREFLTGSSADSDSSSVASNPADPAATPPRSESSDTEPDDEAPSKPKSGPGSTDSCRSTNSVILQGKPKTAAKTLFLLPDGGGSASSYSVIPKLQSDVAVVGINCPYARDPENMTCTWQAMMQSFINEIKRRQPKGPYHLGGWSSGGAFAYVTAEKMIKQGDEVGSLFIFDAPVPQVMEKLPREFYEAVNFTESTAVGTAEPPPYLIPHFMAVVDVMLDYKCKPLQTKKMPNVGLIWADSTVMKEDEAPKMKGMHFMIQKRTNFGPDGWDEVCPGAKFEIVKAVDTNHFTLMTKARVNYVSDLIDKVMG | ||||||
Modified residue | 1770 | O-(pantetheine 4'-phosphoryl)serine | ||||
Sequence: S | ||||||
Modified residue | 1911 | O-(pantetheine 4'-phosphoryl)serine | ||||
Sequence: S | ||||||
Modified residue | 2057 | O-(pantetheine 4'-phosphoryl)serine | ||||
Sequence: S |
Keywords
- PTM
Expression
Induction
Expression is positively regulated by the dothistromin-specific transcription factors aflR and aflJ (PubMed:23207690, PubMed:25986547).
Dothistromin biosynthetic proteins are co-regulated, showing a high level of expression at ealy exponential phase with a subsequent decline in older cultures (PubMed:17683963, PubMed:18262779).
Dothistromin biosynthetic proteins are co-regulated, showing a high level of expression at ealy exponential phase with a subsequent decline in older cultures (PubMed:17683963, PubMed:18262779).
Structure
Family & Domains
Features
Showing features for region, domain, compositional bias.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Region | 10-247 | Starter unit:ACP transacylase (SAT) domain | ||||
Sequence: LVFGDQTYDFVPKLRELFHVKDNPILTAFLEQSHYVVRAQMIQTLPPAEHKAARTFDLADMLKKYVAGKLNPAFQTALSCITQLGVFMREFHDFTKPYPRHDSSYVLGICTGSLAAAAVSSSNSLSELLPIAVQTALIAFRLGLCVTDMRDRLESSEEDRTQPWSVVLFDTDEQTVTKAIKDFCTSNVLPKTKQPWITSASSKTITISGAPRVLKKLSQEPALKDKKTRQIPIYVPAH | ||||||
Domain | 372-805 | Ketosynthase family 3 (KS3) | ||||
Sequence: KSKLAIVSMSGRFPEAQSTDAFWDLLYKGLDVVKEVPKRRWDVETHVDPTGRARNKGATKWGCWLDFAGEFDPRFFSISPKEAPQMDPAQRMALMSTWEAMERGGIVPDTTPSTQRNRIGVFHGVTSNDWMETNTAQNIDTYFITGGNRGFIPGRINFCFEFSGPSFTNDTACSSSLAAIHLACNSLWRGDCDTAVAGGTNMIFTPDGHAGLDKGFFLSRTGNCKPFDDKADGYCRAEGVGTVMVKRLEDALADGDPILGTILDAKTNHSAMSDSMTRPFVPAQIDNMEACLSTAGVDPTSLDYIEMHGTGTQVGDAVEMESVLSVFAPNEQFRGKDQPLYVGSAKANIGHGEGVSGVTSLIKVLLMMQNNTIPPHCGIKPGSKINHNYPDLAARNVHIAFEPKPFLRREGKLRRVLINNFSAAGGNTALLIED | ||||||
Region | 905-1192 | Malonyl-CoA:ACP transacylase (MAT) domain | ||||
Sequence: FAFTGQGSQYLGMGKQLYDSYPMFRSELQGYDRLAQSQGFPSFAHIFTETKGDVEQNLPVVVQLAITCLQMALFNLVTSFGIKASAVVGHSLGEYAALYAAGVLSASDTIYLVGKRAELLQDHCQRGTHAMLACKASEWSLAEITAGKNVEVACVNGPEDTVLSGTVEEIGEVQKTLSAKSIKATLLKLPFAFHSAQVQPILEDFEELAAGATFEKPKLAVISPLLGSVVEDEGVVGPNYLARHCREAVGMVKALGVAKEKGIINEKTIVIEIGPKPLLCGMIKNILG | ||||||
Region | 1307-1327 | Disordered | ||||
Sequence: VQEAPAAKTETKKMSKLDPTK | ||||||
Region | 1340-1483 | N-terminal hotdog fold | ||||
Sequence: HKVIEEKTEPLGAQFTVETDISRKDVNSIAQGHTVDSIPLCTPSFYADIALQVGKYAMDRIRAGHPGAGAIDGRVDVTDLVVDKALIPHGKAPQLLRTNVTMSWPPKMAATTRSAKVTFKTYTADGKLDTDHAYCTVRFTTDSQ | ||||||
Domain | 1340-1658 | PKS/mFAS DH | ||||
Sequence: HKVIEEKTEPLGAQFTVETDISRKDVNSIAQGHTVDSIPLCTPSFYADIALQVGKYAMDRIRAGHPGAGAIDGRVDVTDLVVDKALIPHGKAPQLLRTNVTMSWPPKMAATTRSAKVTFKTYTADGKLDTDHAYCTVRFTTDSQQKSLQKKVPEYKAAIAKLRARDAKGELTHYNTKSGYKLMSSMAHFHPDYKLLDNLVLNEAENEAVSVMNFSSCTDAGIYAAHPAYVDAITQVGGFAMNAKDDTDIDKEVYVNHGWESFQVYKKMEKSVEYVVYSKMTKDPKGDMVHGDTIVLDGDEVVAFFRGLSLRSVPRKALR | ||||||
Region | 1353-1658 | Product template (PT) domain | ||||
Sequence: QFTVETDISRKDVNSIAQGHTVDSIPLCTPSFYADIALQVGKYAMDRIRAGHPGAGAIDGRVDVTDLVVDKALIPHGKAPQLLRTNVTMSWPPKMAATTRSAKVTFKTYTADGKLDTDHAYCTVRFTTDSQQKSLQKKVPEYKAAIAKLRARDAKGELTHYNTKSGYKLMSSMAHFHPDYKLLDNLVLNEAENEAVSVMNFSSCTDAGIYAAHPAYVDAITQVGGFAMNAKDDTDIDKEVYVNHGWESFQVYKKMEKSVEYVVYSKMTKDPKGDMVHGDTIVLDGDEVVAFFRGLSLRSVPRKALR | ||||||
Region | 1510-1658 | C-terminal hotdog fold | ||||
Sequence: LTHYNTKSGYKLMSSMAHFHPDYKLLDNLVLNEAENEAVSVMNFSSCTDAGIYAAHPAYVDAITQVGGFAMNAKDDTDIDKEVYVNHGWESFQVYKKMEKSVEYVVYSKMTKDPKGDMVHGDTIVLDGDEVVAFFRGLSLRSVPRKALR | ||||||
Region | 1665-1734 | Disordered | ||||
Sequence: MDKGIRQRGGKPGAAKGAVAAPAPAKKMVEPVKAASKKETPAAAAPPSPSKAAPPPAPKPAALKASVPKA | ||||||
Compositional bias | 1711-1726 | Pro residues | ||||
Sequence: PSPSKAAPPPAPKPAA | ||||||
Domain | 1733-1812 | Carrier 1 | ||||
Sequence: KADPGKVDEALKIISEESGIALDELTDDSNFTDMGVDSLSSMVITSRLREDLELDLAPDFALFADCPTVASLRTFLAGAA | ||||||
Domain | 1877-1953 | Carrier 2 | ||||
Sequence: SKVFDDALQIISEESGIALDELTDDSNFTDMGVDSLSSMVITSRLREDLELDLSPDWALFADCPTVASLRSFLGGSG | ||||||
Domain | 2020-2099 | Carrier 3 | ||||
Sequence: VARTEALNAALDIIAEESGVAAEDFTDDTIFSDIGIDSLCSMVISSRFREELELDLDSQFSLFVDLPTVAQLREFLTGSS | ||||||
Compositional bias | 2098-2122 | Polar residues | ||||
Sequence: SSADSDSSSVASNPADPAATPPRSE | ||||||
Region | 2098-2149 | Disordered | ||||
Sequence: SSADSDSSSVASNPADPAATPPRSESSDTEPDDEAPSKPKSGPGSTDSCRST | ||||||
Region | 2164-2393 | Thioesterase/Claisen cyclase (TE/CLC) domain | ||||
Sequence: TLFLLPDGGGSASSYSVIPKLQSDVAVVGINCPYARDPENMTCTWQAMMQSFINEIKRRQPKGPYHLGGWSSGGAFAYVTAEKMIKQGDEVGSLFIFDAPVPQVMEKLPREFYEAVNFTESTAVGTAEPPPYLIPHFMAVVDVMLDYKCKPLQTKKMPNVGLIWADSTVMKEDEAPKMKGMHFMIQKRTNFGPDGWDEVCPGAKFEIVKAVDTNHFTLMTKARVNYVSDL |
Domain
The domain architecture includes starter unit:ACP transacylase (SAT), beta-ketoacyl synthase (KS), malonyl-CoA:ACP transacylase (MAT), product template (PT), 3 acyl-carrier domain (ACP), and thioesterase/Claisen cyclase (TE/CLC) domains (PubMed:16649078).
Although duplicated ACP domains are common, pksA is the only fungal PKS containing 3 ACP domains (PubMed:16649078).
The third (C-terminal) ACP is less similar in sequence to the first two and to that of the aflatoxin biosynthetic enzyme aflC (PubMed:16649078).
It is possible that the third ACP domain was acquired by unequal recombination and has since diverged into a slightly different form that may have less functionality or altered specificity (PubMed:16649078).
Although duplicated ACP domains are common, pksA is the only fungal PKS containing 3 ACP domains (PubMed:16649078).
The third (C-terminal) ACP is less similar in sequence to the first two and to that of the aflatoxin biosynthetic enzyme aflC (PubMed:16649078).
It is possible that the third ACP domain was acquired by unequal recombination and has since diverged into a slightly different form that may have less functionality or altered specificity (PubMed:16649078).
Keywords
- Domain
Phylogenomic databases
Family and domain databases
Sequence
- Sequence statusComplete
- Length2,399
- Mass (Da)259,252
- Last updated2005-12-06 v1
- ChecksumC82F86A242F2AFE4
Features
Showing features for compositional bias.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Compositional bias | 1711-1726 | Pro residues | ||||
Sequence: PSPSKAAPPPAPKPAA | ||||||
Compositional bias | 2098-2122 | Polar residues | ||||
Sequence: SSADSDSSSVASNPADPAATPPRSE |