ASCI_ACREG
ID ASCI_ACREG Reviewed; 384 AA.
AC A0A455R4Z0;
DT 26-FEB-2020, integrated into UniProtKB/Swiss-Prot.
DT 05-JUN-2019, sequence version 1.
DT 25-MAY-2022, entry version 10.
DE RecName: Full=Terpene cyclase ascI {ECO:0000303|PubMed:30952781};
DE EC=5.4.99.- {ECO:0000269|PubMed:30952781};
DE AltName: Full=Ascofuranone/ascochlorin biosynthesis clusters protein I {ECO:0000303|PubMed:30952781};
DE Flags: Precursor;
GN Name=ascI {ECO:0000303|PubMed:30952781};
OS Acremonium egyptiacum (Oospora egyptiaca).
OC Eukaryota; Fungi; Dikarya; Ascomycota; Pezizomycotina; Sordariomycetes;
OC Hypocreomycetidae; Hypocreales; Hypocreales incertae sedis; Acremonium.
OX NCBI_TaxID=749675;
RN [1]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, CATALYTIC ACTIVITY,
RP BIOPHYSICOCHEMICAL PROPERTIES, DISRUPTION PHENOTYPE, INDUCTION, MUTAGENESIS
RP OF ASP-61; GLU-103; ASP-296; GLU-353 AND ASP-355, AND PATHWAY.
RC STRAIN=F-1392;
RX PubMed=30952781; DOI=10.1073/pnas.1819254116;
RA Araki Y., Awakawa T., Matsuzaki M., Cho R., Matsuda Y., Hoshino S.,
RA Shinohara Y., Yamamoto M., Kido Y., Inaoka D.K., Nagamune K., Ito K.,
RA Abe I., Kita K.;
RT "Complete biosynthetic pathways of ascofuranone and ascochlorin in
RT Acremonium egyptiacum.";
RL Proc. Natl. Acad. Sci. U.S.A. 116:8269-8274(2019).
RN [2]
RP BIOTECHNOLOGY.
RX PubMed=12084465; DOI=10.1016/s0925-4439(02)00086-8;
RA Nihei C., Fukai Y., Kita K.;
RT "Trypanosome alternative oxidase as a target of chemotherapy.";
RL Biochim. Biophys. Acta 1587:234-239(2002).
RN [3]
RP BIOTECHNOLOGY.
RX PubMed=12798927; DOI=10.1016/s1383-5769(03)00012-6;
RA Yabu Y., Yoshida A., Suzuki T., Nihei C., Kawai K., Minagawa N.,
RA Hosokawa T., Nagai K., Kita K., Ohta N.;
RT "The efficacy of ascofuranone in a consecutive treatment on Trypanosoma
RT brucei brucei in mice.";
RL Parasitol. Int. 52:155-164(2003).
RN [4]
RP BIOTECHNOLOGY.
RX PubMed=20688188; DOI=10.1016/j.parint.2010.07.006;
RA Nakamura K., Fujioka S., Fukumoto S., Inoue N., Sakamoto K., Hirata H.,
RA Kido Y., Yabu Y., Suzuki T., Watanabe Y., Saimoto H., Akiyama H., Kita K.;
RT "Trypanosome alternative oxidase, a potential therapeutic target for
RT sleeping sickness, is conserved among Trypanosoma brucei subspecies.";
RL Parasitol. Int. 59:560-564(2010).
CC -!- FUNCTION: Epoxide hydrolase; part of the asc-2 gene cluster that
CC mediates the biosynthesis of ascofuranone, a strong inhibitor of
CC cyanide-insensitive alternative oxidases and a promising drug candidate
CC against African trypanosomiasis (PubMed:30952781). The first step in
CC the pathway is performed by the non-reducing polyketide synthase ascC
CC that produces orsellinic acid by condensing acetyl-CoA with 3 malonyl-
CC CoA units (PubMed:30952781). Orsellinic acid is then prenylated by the
CC prenyltransferase ascA to yield ilicicolinic acid B (PubMed:30952781).
CC Ilicicolinic acid B is further reduced to ilicicolin B by the reductase
CC ascB (PubMed:30952781). The halogenase ascD then chlorinates ilicicolin
CC B to produce ilicicolin A which is converted to ilicicolin A epoxide by
CC the cytochrome P450 monooxygenase ascE that catalyzes stereoselective
CC epoxidation of the terminal double bond of the prenyl group
CC (PubMed:30952781). Ilicicolin A epoxide is the last common precursor
CC for the biosynthesis of ascofuranone and ascochlorin (PubMed:30952781).
CC The terpene cyclase ascF produces a monocyclic terpene, and the
CC cyclization reaction is proposed to be initiated by protonation of the
CC terminal epoxide of ilicicolin A epoxide to generate a monocyclic
CC tertiarycation, which is followed by a series of hydride and methyl
CC shifts with abstraction of proton, leading to the formation of the
CC (14S,15R,19R)-trimethylcyclohexanone ring structure of ilicicolin C,
CC which is finally reduced to ascochlorin by the dehydrogenase ascG
CC (PubMed:30952781). On the other hand, ilicicolin A epoxide is
CC hydroxylated by the cytochrome P450 monooxygenase ascH, and the
CC resultant product is cyclized by the terpene cyclase ascI to
CC ascofuranol via protonation-initiated epoxide ring opening, which
CC facilitates the 6-endo-tet cyclization to form the tetrahy-drofuran
CC ring (PubMed:30952781). Finally, ascofuranol is oxidized into
CC ascofuranone by ascJ (PubMed:30952781). {ECO:0000269|PubMed:30952781}.
CC -!- CATALYTIC ACTIVITY:
CC Reaction=16-hydroxy-ilicicolin A epoxide = ascofuranol;
CC Xref=Rhea:RHEA:63108, ChEBI:CHEBI:146158, ChEBI:CHEBI:146159;
CC Evidence={ECO:0000269|PubMed:30952781};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:63109;
CC Evidence={ECO:0000269|PubMed:30952781};
CC -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC Kinetic parameters:
CC KM=50.4 uM for the product of ascH {ECO:0000269|PubMed:30952781};
CC Vmax=129 nmol/min/mg enzyme toward the product of ascH
CC {ECO:0000269|PubMed:30952781};
CC -!- PATHWAY: Secondary metabolite biosynthesis; terpenoid biosynthesis.
CC {ECO:0000269|PubMed:30952781}.
CC -!- SUBCELLULAR LOCATION: Membrane {ECO:0000255}; Multi-pass membrane
CC protein {ECO:0000255}.
CC -!- INDUCTION: Expression is induced on AF medium.
CC {ECO:0000269|PubMed:30952781}.
CC -!- DISRUPTION PHENOTYPE: Impairs the production of ascofuranone and leads
CC to the accumulation of the product of ascH.
CC {ECO:0000269|PubMed:30952781}.
CC -!- BIOTECHNOLOGY: Ascofuranone is a specific inhibitor of trypanosome
CC alternative oxidase (TAO), and quickly kills African trypanosomes in
CC vitro and cures infected mice. As an essential factor for trypanosome
CC survival, TAO is a promising drug target due to the absence of
CC alternative oxidases in the mammalian host.
CC {ECO:0000269|PubMed:12084465, ECO:0000269|PubMed:12798927,
CC ECO:0000269|PubMed:20688188}.
CC -!- SIMILARITY: Belongs to the membrane-bound ascI terpene cyclase family.
CC {ECO:0000305}.
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DR EMBL; LC406757; BBF25321.1; -; Genomic_DNA.
DR AlphaFoldDB; A0A455R4Z0; -.
DR UniPathway; UPA00213; -.
DR GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR GO; GO:0016853; F:isomerase activity; IEA:UniProtKB-KW.
DR GO; GO:0016114; P:terpenoid biosynthetic process; IEA:UniProtKB-UniPathway.
PE 1: Evidence at protein level;
KW Glycoprotein; Isomerase; Membrane; Signal; Transmembrane;
KW Transmembrane helix.
FT SIGNAL 1..25
FT /evidence="ECO:0000255"
FT CHAIN 26..384
FT /note="Terpene cyclase ascI"
FT /evidence="ECO:0000255"
FT /id="PRO_5019795226"
FT TRANSMEM 82..102
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TRANSMEM 119..139
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TRANSMEM 164..184
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TRANSMEM 194..214
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TRANSMEM 235..255
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TRANSMEM 291..311
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TRANSMEM 330..350
FT /note="Helical"
FT /evidence="ECO:0000255"
FT CARBOHYD 109
FT /note="N-linked (GlcNAc...) asparagine"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00498"
FT CARBOHYD 258
FT /note="N-linked (GlcNAc...) asparagine"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00498"
FT CARBOHYD 372
FT /note="N-linked (GlcNAc...) asparagine"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00498"
FT MUTAGEN 61
FT /note="D->A: Leads to significant loss of activity."
FT /evidence="ECO:0000269|PubMed:30952781"
FT MUTAGEN 103
FT /note="E->A: Leads to significant loss of activity."
FT /evidence="ECO:0000269|PubMed:30952781"
FT MUTAGEN 296
FT /note="D->A: Leads to significant loss of activity."
FT /evidence="ECO:0000269|PubMed:30952781"
FT MUTAGEN 353
FT /note="E->A: Leads to significant loss of activity."
FT /evidence="ECO:0000269|PubMed:30952781"
FT MUTAGEN 355
FT /note="D->A: Leads to significant loss of activity."
FT /evidence="ECO:0000269|PubMed:30952781"
SQ SEQUENCE 384 AA; 41823 MW; 8BD49886F8854A87 CRC64;
MPQLAGKLIL AGLIPLGAWV LHGFASCNGL IQMFEDFGKQ TVLSDGVTDY TGAFTGLEGL
DRLLRTLLNF FWPVANGHDW ALSLHAFMFA GQGVPLLVLN MLEGARPGNK SLVVSYVTVF
GILYMVVGLA IMAPLYLFLH LLTSRTATAP SKAKVAVDPN TAKAVGFGVF VGYVLPTIFM
SLPHPSLLST DTKVLSVVFW QAVPLWASVC AYFASTALGQ SATSRSSSNL PSALGAVYAA
SLIIATATHV ATFAISANLS DTWSGIFTFL IPPNPFNTDM RISSFLEGAT WFLQWDYTMM
SLAYMVWAIG IRHGVEVPRS SHHFETLGKI ALRSMAKLLV MGPIGAALSL VWERDQLLWQ
LDSESGEKGE KNRSRRMSRK WMFS
