Biochemistry
[3.1.0]-hexane ring system.
Page 4 of 5
The modification pre-
1
6
MS gave the expected fragmentation ions as shown in
Scheme 4.
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
vents cyclization of the amino acid and formation of the
1
Δ -piperidine carboxylate, analogous to that observed in
bacterial arginine biosynthesis. N-acetylation reflects at
A proposed route for the formation of the aziridino[1,2-
a]pyrrolidine moiety is provided in Scheme 5 (highlight-
ed in blue are steps validated by experimentation). Our
previous studies, including in vitro reconstitution and
genetic knockout of aziC2, have shown that N-
acetylation of glutamic acid 3 by AziC2 serves as a
least one mechanism by which azabicycle biosynthesis
16
can be primed. Taken together with our previous work
with AziC2, our studies here provide support are fully
consistent with the involvement of AziC3, an N-
acetylglutamate kinase, giving an acyl phosphate 5 that
facilitates reduction to the aldehyde 6 via N-acetyl-γ-
glutamyl-phosphate reductase, AziC4. A transketolase
would give a two carbon extension, where subsequent
“
protection step” in the biosynthesis of the 1-azabicyclo-
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 5
O
O
O
O
H
H
H
H2N
OH
N
N
N
transamination would generate an amine diol 10. Dehy-
dration would enable oxidation to give a diol 13.
R
OH
R
OH
O
R
OH
O
AziC2
AziC3
AziC4
16
A
2-O3PO
sulfotransferase could facilitate aziridine ring formation
through sulfation. Dehydrogenation and deprotection of
the amine would generate the aziridinopyrrolidine moie-
ty 19. Experiments are underway to evaluate the remain-
ing biosynthetic steps.
HO
O
HO
O
O
H
7
3
4
5
6
O
O
O
H
N
H
N
H
N
H
N
R
OH
R
OH
R
OH
R
OH
OH
OH
O
NH2 H2N
HO
HO
HO
OH
OH 11
11
7
Thiamin
8
HO
9
HO 10
ASSOCIATED CONTENT
O
O
O
H
N
H
N
H
N
R
OH
R
OH
R
OH
[O*]
[D]
Supporting Information. “This material is available free
of charge via the Internet at http://pubs.acs.org.”
[DH]
HO
*
HO
NH2
HO
HO
NH2
OSO3-
NH2
OH
*
HO 12
13
14
Corresponding Author
*Email: watanabe@chem.tamu.edu
O
O
O
O
N
H
N
H
H
H
N
N
N
R
OH
R
HO
HO
OH
R
OH
N
R
OH
[D]
H
N
HO
HO
NH2
Author Contributions. The manuscript was written
through contributions of all authors. / All authors have giv-
en approval to the final version of the manuscript
HO
HO
HO
HO
OSO3-
1
5
16
17
18
O
N
H2N
OH
Funding. We are grateful to the National Science Founda-
tion (CHE-1308151) and the Welch Foundation (A-1828)
for financial support of this work.
R =
*
O
HO
*
HO 19
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