Progress in the Chemistry of Cytochalasans
89
HN
O
SEnz
O
O
HN
OH
O
O
4
5
HN
O
O
4
5
2'
3'
HN
O
SEnz
O
O
HN
O
4
5
2'
3'
HN
O
A C E 1 R A P 1
O
O
OH
OH
OH
HN
OH
O
O
$ R U \ ] D H
D H
$ Q LG X OD Q V $ Q LJ H U
N
$ QLGXODQV
A3 (niduporthin)
$RU\]DH
HO
CcsACcsB
SYN2RAP2
A C E 1
A
1 ×acetyl-CoA
8 ×Mal-CoA
3 ×SAM
1 ×Phe-AMP
1 ×acetyl-CoA
7 ×Mal-CoA
1 ×SAM
1 ×Trp-AMP
1 ×acetyl-CoA
8 ×Mal-CoA
3 ×SAM
1 ×Tyr-AMP
$
%
&
A2 (niduclavin
A4
A5
Scheme 2 The outcome of investigations into the early stages of cytochalasan biosynthesis (A–C)
The remaining cryptic gene pair ACE1/RAP1 in the ACE1 gene cluster from M.
oryzae has been investigated by Cox and co-workers [251]. Expression of ACE1
alone in A. oryzae produced a polyenyl pyrone A4, which was believed to be a shunt
product since it lacked the expected amino acid moiety (Scheme 2C). However, coexpression of ACE1 and RAP1, an amide A5, closely resembling A1 from A. oryzae
co-expressed with ccsA and ccsC, was isolated (Scheme 2C).