Legonoxamines A-B, two new hydroxamate siderophores from the soil bacterium, Streptomyces sp. MA37

Article abstract of DOI:10.1016/j.tetlet.2018.11.063

Two new siderophores belonging to the hydroxamate class, Legonoxamine A (1) and B (2) have been isolated from the soil bacterium, Streptomyces sp. MA37, together with one known compound, desferrioxamine B (3). Their structures were elucidated based on spectroscopic methods including 1D, 2D NMR, MS, as well as by comparison with the relevant literatures. To our knowledge, this is the first report describing a siderophore containing the N-hydroxyl phenylacetyl cadaverine (HPAC) moiety in the structure. Based on bioinformatics analysis and previous knowledge of the biosynthesis of the hydroxamate-type siderophore, the biosynthetic gene cluster (lgo) responsible for the production of 1–3 was identified in the annotated genome of the producing strain. The supplementation of phenylacetate and benzoate analogues with meta substitution into the cultures of Streptomyces sp. MA37 resulted in the production of new legonoxamine A derivatives as observed in LC-HR-ESIMS, suggesting that the legonoxamine biosynthetic pathway has a good degree of natural flexibility of accepting unnatural precursors with different functional groups.

Full text of DOI:10.1016/j.tetlet.2018.11.063

Accepted Manuscript
Legonoxamines A-B, two new hydroxamate siderophores from the soil bacte-
rium, Streptomyces sp. MA37
Fleurdeliz Maglangit, Ming Him Tong, Marcel Jaspars, Kwaku Kyeremeh, Hai
Deng
PII:
S0040-4039(18)31410-2
https://doi.org/10.1016/j.tetlet.2018.11.063
TETL 50448
DOI:
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
11 September 2018
21 November 2018
24 November 2018
Please cite this article as: Maglangit, F., Tong, M.H., Jaspars, M., Kyeremeh, K., Deng, H., Legonoxamines A-B,
two new hydroxamate siderophores from the soil bacterium, Streptomyces sp. MA37, Tetrahedron Letters (2018),
doi: https://doi.org/10.1016/j.tetlet.2018.11.063
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Tetrahedron
Legonoxamines A-B, two new hydroxamate siderophores from the soil bacterium,
Streptomyces sp. MA37
ab
a
a
c
a
Fleurdeliz Maglangit *, Ming Him Tong , Marcel Jaspars , Kwaku Kyeremeh , Hai Deng 
a
Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland, UK
College of Science, University of the Philippines Cebu, Lahug, Cebu City, 6000, Philippines
b
c
Department of Chemistry, University of Ghana, P.O. Box LG56, Legon-Accra, Ghana
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
Two new siderophores belonging to the hydroxamate class, Legonoxamine A (1) and B (2) have
been isolated from the soil bacterium, Streptomyces sp. MA37, together with one known
compound, desferrioxamine B (3). Their structures were elucidated based on spectroscopic
methods including 1D, 2D NMR, MS, as well as by comparison with the relevant literatures. To
our knowledge, this is the first report describing a siderophore containing the N-hydroxyl
phenylacetyl cadaverine (HPAC) moiety in the structure. Based on bioinformatics analysis and
previous knowledge of the biosynthesis of the hydroxamate-type siderophore, the biosynthetic
gene cluster (lgo) responsible for the production of 1-3 was identified in the annotated genome of
the producing strain. The supplementation of phenylacetate and benzoate analogues with meta
substitution into the cultures of Streptomyces sp. MA37 resulted in the production of new
legonoxamine A derivatives as observed in LC-HR-ESIMS, suggesting that the legonoxamine
biosynthetic pathway has a good degree of natural flexibility of accepting unnatural precursors
with different functional groups.
Available online
Keywords:
Siderophores
Hydroxamates
Legonoxamine
Streptomyces sp MA37
Precursor-directed biosynthesis
2
009 Elsevier Ltd. All rights reserved.
6
,7
1
. Introduction
amides) (i.e. desferrioxamines) , catecholates (i.e.
8
9,10
enterobactins) , carboxylates (i.e. achromobactin)
siderophores with mixed ligands. There are more than 500
different siderophores, of which only about 270 have been
, and
11
Iron is an essential element for the growth of almost all forms
of life, serving as a cofactor in enzymatic processes, oxygen
metabolisms, electron transfer, and DNA and RNA syntheses.
It is also required for biofilm formation because Iron regulates
surface motibility and stabilizes the polysaccharide matrix.
Because of the low bioavailability of iron in the environment,
microorganisms have developed specific uptake strategies such
as production of siderophores, metal-chelating molecules with
low molecular weight (200-2000Da) that are produced by
1
1
structurally characterized.
2
In our screening program to discover novel natural products
, we have identified a talent soil
bacterium, Streptomyces sp. MA37, a Ghanaian isolate that has
the capacity of producing two pyrrolizidine alkaloid
legonmycins , one carbazole alkaloid neocarazostatin A
and a range of fluorinated metabolites
12–15
from Ghanaian isolates
16
17–19
2
0,21
3
,4
.
microorganisms, especially under iron-limiting conditions.
The role of siderophores is to scavenge the extracellular iron
from different terrestrial and aquatic habitats and transport them
to microbial and plant cells via specific high-affinity uptake
In this study, we report the isolation and characterization of
two new desferrioxamine siderophore derivatives from
Streptomyces sp. MA37, which were named legonoxamine A 1
and B 2, after their association with Legon, Ghana, the location
of the University of Ghana. Both legonoxamines contain a
unique moiety, N-hydroxyl phenylacetyl cadaverine (HPAC),
which, to our best knowledge, has not been found in other
known siderophores. Interestingly, we also isolated the known
3,5
receptors.
Siderophores are a highly diverse group of compounds and
they are classified into four main categories based on the
chemical nature of the moieties donating the oxygen ligands for
3+
1
Fe coordination. These four classes are: hydroxamates (N-OH
—
——
 Corresponding author. Tel.: +44 1224 272953; fax: +44 1224 272291; e-mail: h.deng@abdn.ac.uk (H. Deng)
Corresponding author. Tel.: +63 032 232 8185; fax: +63 032 232 8185; e-mail: ffmaglangit@up.edu.ph (F. Maglangit)

2
Tetrahedron
siderophore, desferrioxamine B (3) that have been known to be
produced by various bacteria.
The singlet proton signal at 3.79 ppm (H-7”) showed HMBC
correlations to the quaternary aromatic carbon C-8” (135.0ppm)
1
In silico analysis of the annotated genome of Streptomyces
sp. MA37 allowed the identification of the biosynthetic gene
clusters (lgo). A precursor-directed biosynthesis approach was
employed in order to access new legonoxamine derivatives. The
biosynthetic machinery exhibited relaxed substrate specificity
with meta-substituted phenylacetate and benzoate analogues
that were administered.
2. Results and Discussion
Streptomyces sp. MA37 was cultivated in the presence of
HP20 resin (35g/L medium). After 7-day fermentation (12L),
the aqueous solution was filtered and HP20 resin was extracted
with methanol (3x500 ml). The crude extract was concentrated
under vacuum, followed by fractionation using the reversed
phase solid phase extraction (SPE). Subsequently the 100%
methanol fraction was then subjected to semi-preparative
reversed-phase HPLC resulting in the isolation of compounds 1
(5.3 mg), 2 (3.2 mg), and 3 (4.5 mg).
The molecular formula of 1 was established as C31
H
53
N
6
O
8
Figure 1. Legonoxamine A 1 with COSY (▬) and key HMBC
(→) correlations, Legonoxamine B 2, and the known compound
desferrioxamine B 3
by high resolution electron spray ionization mass spectrometry
+
(
HR ESIMS) (m/z 637.3904 [M+H] ∆ -1.957 ppm) (Fig. S1-
S3). The molecular formula suggested 9 degrees of unsaturation.
1
Interpretation of H, HMBC and edited HSQC NMR data (Table
1
, Fig. S4-S8)) of 1 revealed the presence of 20 methylenes, 5
methines and 6 quaternary carbons leading to the sub-formula
45. The presence of 5 methines (127.0-129.2 ppm) and 1
and the carbonyl carbon at C-6” (173.6 ppm), signifying the
presence of a phenyl acetyl moiety in the structure (substructure
F). The connectivity of this moiety to the HSC residue
(substructure E) was established on the basis of HMBC
correlations from H-5” (3.65 ppm) and H-7” (3.79 ppm) to C-6”
(173.6 ppm) (Fig. S9) to form one N-hydroxy-N-phenylacetyl
cadaverine (HPAC) unit, respectively. The identity of the
phenylacetyl moiety was further supported by comparison of the
HPLC analysis of the hydrolysate of legonoxamine A 1 against
the standard phenyl acetic acid. A prominent peak (RT = 14.4
min) observed in the hydrolysate shared the same RT as the one
of phenyl acetic acid (Fig. S23).
C H
31
quaternary carbon (135.0 ppm) suggested the presence of one
aromatic ring, which together with the presence of five
additional quaternary carbonyl carbons (171.0-174.7 ppm)
accounted for a total of 9 double bond equivalents.
1
1
Analysis of the H- H COSY spectrum revealed 6 spin
systems with repeating motifs, one consisting of H-1 through H-
5, H-1’ through H-5’, and H-1” through H-5”, and the other
comprising H-7 through H-8 and H-7’ through H-8’, and the
presence of one aromatic spin system H-8” through H-13”.
+
The molecular ion peak of 2 was established as C17
25
H N
2
O
5
The long-range couplings observed in the HMBC
experiments established the connectivity of the 6 substructures
including two succinyl units (substructures B and D) and three
N-hydroxy-cadaverine units (substructures A, C and E) (Fig.
S9). The cross peaks from H-7 (2.49 ppm) and H-8 (2.79 ppm)
to C-6 (172.8 ppm) and C-9 (174.7 ppm), and H-7’ (2.49 ppm)
and H-8’ (2.79 ppm) to C-6’ (172.9 ppm) and C-9’ (173.8 ppm),
indicated the presence of two succinyl groups. The HMBC
correlation from nitrogen-bearing methylene at H-5 (3.65 ppm)
to the carbonyl carbon at C-6 (172.8 ppm) confirmed the
connectivity of substructures A with B by an amido bond
between C-5 and C-7. Similarly, the connectivities of
substructures B with C, C with D, and D with E were elucidated
by HMBC correlations from H-1' (3.17 ppm) to C-9 (174.7
ppm), H-5' (3.65 ppm) to C-6' (172.9 ppm), and H-1" (3.17 ppm)
to C-9' (173.8 ppm), respectively. The remaining atoms were
estimated to be hydroxyl groups attached to nitrogen, from the
molecular formula of 1 to form three N-hydroxy groups.
+
by HR ESIMS (m/z 337.1760 [M+H] ∆ -0.287 ppm), which
required 7 degrees of unsaturation (Fig. S10-S12).
Based on the 1D and 2D NMR data, 2 showed a similar
HPAC pattern as in 1 with a succinyl moiety in the structure
(Fig. S13-S16). The cross peaks from H-3’ (2.57 ppm) and H-
2’ (2.43 ppm) to C-4’ (176.0 ppm) and C-1’ (174.0 ppm)
supported the presence of the succinyl residue.
1
13
Inspection of the H, C (Table 1), and HR ESIMS data (m/z
+
5
61.3583 amu [M+H] ∆ -2.117 ppm) (Fig. S17-S22) of 3
indicated that it was the known compound, desferrioxamine B
5,23–25
which can be isolated from various Streptomyces species.
Final structural analysis of 1 and 2 were completed by
comparison of the 1D and 2D NMR to known spectra for
22–27
desferrioxamine compounds.
It was evident that the proton
and carbon chemical shifts at C-7” (in 1) and C-7 (in 2) had
1
13
remarkably changed from 2.1 ppm ( H) and 19.0 ppm ( C) in
1
13
desferrioxamine B to 3.79 ppm ( H) and 39.8 ppm ( C) in 1 and
, respectively. The presence of the aromatic ring ( C 127-135
Analysis of the 2D NMR data in 1 revealed the presence of
two N-hydroxy-N-succinyl cadaverine (HSC) units, which were
in agreement with bisucaberin B, a linear hydroxamate class
siderophore from the marine bacterium Tenacibaculum
mesophilum, which contains similar HSC functional groups in
13
2
ppm) makes 1 and 2 unique from other siderophores (Table 1,
Fig. 1).
On the basis of the evidence in this study, 1 and 2 were
confirmed as new siderophores belonging to the hydroxamate
2
2
the structure.

The lgoA and lgoB genes encode enzymes with similarity to
PLP-dependent amino acid decarboxylases and FAD-dependent
amine monooxygenases, respectively, and are proposed to
catalyze the first two steps of the biosynthesis of the
legonoxamines 1-2 and desferrioxamine B 3. The protein
encoded by lgoC is similar to acyl-CoA transferase DesC in the
A
B
29
desferrioxamine pathway from Streptomyces coelicolor. It is
believed that LgoC catalyses the acylation of N-
hydroxycadaverine 5 using both acetyl CoA and phenylacetyl
CoA as substrates to give the hydroxamic acids 6, which
undergo ATP-dependent oligomerization to give the 1 and 3,
both catalyzed by LgoD. Legonoxamine B 2 is likelyto be either
a breakdown product of 1 during the chemical workup or a
degraded shunt metabolite during the biosynthesis of 1.
Precursor-directed biosynthesis is a powerful approach to
enable the incorporation of unnatural precursors with diverse
functional groups, expanding the pool of ‘unnatural’ natural
35
products. Additionally, region- and chemo- selectively
modified and modifiable functional groups can be introduced
using this approach. Utilizing this approach, new analogues of
bioactive natural products can be prepared in a matter of days
3
6
compared to a more lengthy and costly synthetic approach.
Thus, our next focus on interrogating the natural degree of
flexibility of the legonoxamine biosynthetic pathway.
The incorporation of phenylacetyl moiety into 1 and 2 is
unprecedented, suggesting that the acyltransferase LgoC,
responsible for the biotransformation of acyl CoA and N-
hydroxycadaverine into hydroxamic acids, may have a high
degree of natural flexibility, which renders this position ideal for
modification through precursor-derived biosynthesis. This
provided encouragement that the incorporation of a variety of
phenyl acetate and benzoate derivatives into legonoxamines
might be feasible. To validate this hypothesis, six phenylacetate
Figure 2. A. The biosynthetic gene cluster of legonoxamines
and 2, and desferrioxamine B 3 in Streptomyces sp. MA37.
B. A proposed biosynthetic model of 1-3.
1
class, for which the names of legonoxamines A and B are
proposed, respectively, after their association with Legon,
Ghana.
The MS/MS fragmentation data of 1 (m/z 690.3016 amu
(PAc) derivatives and benzoate (Table S1) were added to
[
M+Fe–2H]) suggested the presence of legonoxamine A (1)
chelated with iron (C31 Fe). The LC MS isotopic pattern
confirmed the presence of the four stable isotopes ( Fe, Fe,
individual cultures of Streptomyces sp. MA37 at the onset of
siderophore production. The cultures were harvested after 7-day
fermentation and the extracts were analyzed by LC-HR-ESIMS.
Notably, the supplemented PAc analogues substituted at meta
position and benzoate resulted in the production of new
legonoxamine A 1 derivatives with the expected molecular ion
being detected (Fig. S24-26, Table S1). Correct incorporation of
the PAc/benzoate analogues were confirmed through inspection
of the MS-MS spectra. Furthermore, the incorporation of 3-
H
50
N
6
O
8
5
4
56
57
58
Fe, Fe) of the iron-siderophore complex (Fig. S2-S3). Two
3+
molecules of 2 was found bound to Fe at m/z 726.2557
2
+
[
1
2M+Fe-3H] , C34
H
46
N
4
+
O
10Fe and three molecules at m/z
15Fe (Fig. S11-S12). Each
062.4258 [3M+Fe-4H] , C51
H
70
N O
6
hydroxamate group in the structure provides two oxygens (-
CONOH-) which form a bidentate ligand with iron, resulting in
a highly stable, hexadentate octahedral iron (III) complex.
(
trifluoromethyl) phenylacetate was further confirmed in the
F-NMR of the sample at 600 MHz. A new organofluorine
1
9
In silico analysis of the annotated genome of Streptomyces
sp. MA37 allowed the identification of the putative biosynthetic
gene cluster (lgo) (Fig. 2A) that directs the biosynthesis of 1-3.
The lgo gene cluster spans ~40 kbp of genomic DNA and
contains 6 open reading frames (ORFs) with predicted functions
signal at 77ppm was observed in the fermentation culture when
supplemented with the trifluoro precursor (Fig. S27).
Interestingly, no incorporation were observed for PAAs
substituted at para position or trans-cinnamic acid, for example,
4-chlorophenylacetic acid, and 4-(bromomethyl)phenylacetic
acid.
28
that were assigned based on homology analysis.
The lgo cluster contains a cassette of four genes (lgoA-D)
that typically direct the biosynthesis of 1-3 and two auxiliary
genes responsible for transcriptional and transport functions
Legonoxamine A (1) were initially screened for antibacterial
and antifungal activities but does not show any significant
activity.
(
lgoE and F, respectively), and shows high homology with the
28–33
reported biosynthetic gene clusters for desferrioxamines.
Based on bioinformatics analysis and our current understanding
30–32,34
of the desferrioxamine-type natural products,
a possible
legonoxamine biosynthetic pathway is proposed (Fig. 2B).

4
Tetrahedron
Table 1. NMR Spectroscopic Data for Legonoxamine A 1, B 2 and 3 (600 MHz, CD OD, 298K)
3
Desferrioxamine B (3)
13C 1H mult (J, Hz)
Legonoxamine A (1)
Legonoxamine B (2)
1H mult. (J, Hz)
13C
1H mult. (J, Hz)
2.91, t (7)
1.51, m
1.35, m
1.65, m
3.65, m
-
13C
39.9
29.7
26.0
27.0
48.6
170.6
39.8
1
2
3
4
5
6
7
8
9
40.1
29.7
24.6
27.1
48.8
172.2
25.8
28.5
174.8
39.7
29.7
24.6
27.1
48.8
172.2
25.8
28.5
173.4
39.7
29.7
24.6
27.1
48.8
172.2
19.9
2.92, t (7)
1.53, m
1.33, m
1.63, m
3.63, t (7)
-
40.0
3.62, t (7)
1.50, m
1.30, m
1.64, m
3.63, t (7)
-
29.6
24.9
27.1
48.4
172.8
25.9
2.58, t (7)
2.76, t (7)
-
2.49, t (7)
2.79, t (7)
-
3.79, s
28.5
174.7
39.2
1
’
’
3.17, t (7)
1.53, m
1.33, m
1.63, m
3.63, t (7)
-
3.17, t (7)
1.51, m
1.35, m
1.65, m
3.65, m
-
174.0
31.3
-
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
29.6
2.43, t (7)
2.57, t (7)
-
’
24.9
30.1
’
27.1
176.0
’
48.4
’
172.9
25.9
’
2.45, t (7)
2.76, t (7)
-
2.49, t (7)
2.79, t (7)
-
’
28.5
’
173.8
39.2
”
”
”
”
”
”
”
3.17, t (7)
1.53, m
1.33, m
1.63, m
3.63, t (7)
-
3.17, t (7)
1.51, m
1.35, m
1.65, m
3.65, m
-
29.6
24.9
27.1
48.4
173.6
39.8
135.0
129.2
127.4
128.0
127.4
129.2
2.09, s
3.79, s
-
8
”(1) / 8 (2)
135.0
129.4
127.4
128.2
127.4
129.4
9
” (1) / 9 (2)
7.28, m
7.21, m
7.30, m
7.21, m
7.28, m
7.28, m
7.21, m
7.30, m
7.21, m
7.28, m
1
1
1
1
0” (1) / 10 (2)
1” (1) / 11 (2)
2” (1) / 12 (2)
3” (1) / 13 (2)
3
. Conclusion
bacterial isolate was cultured following the guidelines given by the
International Streptomyces Project (ISP) at 28 C, supplemented
with 2 mM potassium fluoride.
o
In summary, we have discovered two new structures
containing phenylacetyl moiety, legonoxamine A 1 and B 2
together with the known siderophore metabolite, desferrioxamine
B 3 from a soil isolate, Streptomyces sp. MA37. Genome mining
of the annotated genome of the producing MA37 strain allowed
the identification of the biosynthetic gene cluster (lgo) of
legonoxamines (1-2) and desferrioxamine B 3. The supplemented
PAc analogues with meta substitution and benzoate resulted in the
production of new analogues of legonoxamines as observed in LC-
HR-ESIMS and MS/MS fragmentation analysis, suggesting that
the putative acyltransferase, LgoC, may display a good degree of
substrate flexibilities. The biochemical characterization and
substrate tolerance of LgoC is under evaluation and will be
reported accordingly.
The crude sample was fractionated on a C18 solid phase
extraction (SPE) column using 25% MeOH in water (SPE 25),
followed by 50% MeOH (SPE 50), then by 100% MeOH (SPE
100). Finally, the column was flushed with 100% methanol
containing 0.05% trifluoroacetic acid (SPE 100 TFA). The eluents
were concentrated under reduced pressure and each fraction was
subjected to LC MS analysis.
The compounds of interest were detected in the SPE 100
1
fraction by LC-MS and H NMR analysis. Purification of this
fraction was carried out by reversed phase C18 High Performance
Liquid Chromatography, HPLC (ACE 10uM 10 x 250 mm
column) using a mixture of methanol, water and TFA (0.05%) as
an eluent with a linear gradient from 0 to 100% MeOH over 45
min and a solvent flow of 1.5 mL/min. All the employed chemicals
were HPLC grade.
4. Experimental section
4.1 Extraction and Isolation
Streptomyces sp. MA37 was isolated from the rhizosphere of a
Moracear Bark Cloth tree (Antiaris toxicaria), growing in the
21
University of Ghana Botanical Gardens, Legon, Africa. The pure

5
4
.2 Structure Elucidation
Supplementary Material
The structure was deduced by High-Resolution Electrospray
1
13
LC MS, NMR Spectra of 1, 2, and 3, including H, C, COSY,
HSQC in CD OD, and feeding experiment results are available in
the Supplementary data.
Ionisation Mass Spectrometry (HR-ESIMS), 1D and 2D NMR
spectroscopy. HR-ESIMS was determined using LC MS Thermo
Scientific MS system (LTQ Orbitrap) coupled to a Thermo
Instrument HPLC system (Accela PDA detector, Accela PDA
autosampler and Accela Pump, C18 Sunfire 150 × 46mm
3
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2
1.
methanol-0.05% trifluoroacetic acid, solvent B- methanol; linear
gradient from 20% to 100% methanol, flow rate 1.0 mL/min,
monitored at 254 nm.
4
.4 Feeding Experiment
2
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The MA37 culture was separately grown in 250-mL
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Erlenmeyer flasks containing 100-mL ISP2, each supplemented
with commercially available and synthetic precursors of the
benzoic acid and phenyl acetic acid moiety to make 1.0 mM of the
solution. The benzoic acid was purchased from BDH Chemicals
LTD, the 4-(bromomethyl)phenylacetic acid, 3-(methylthio)
phenylacetic acid, 3-(trifluoromethyl)phenylacetic acid, and trans-
cinnamic acid were purchased from Sigma Aldrich, and 4-
chlorophenylacetic acid from Merck. The reagents used for the
fermentation feeding experiment were 95-99.5% pure and were
used as received.
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shaker. After 7 days of fermentation, it was added with Diaion®
HP-20 (3g/50mL solution), and incubated overnight. The solution
was filtered and the resin was extracted with methanol. The crude
extract was concentrated in the rotary evaporator and each sample
was subjected to LC MS analysis.
Acknowledgements
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KK, HD and MJ are grateful for the financial support through
Leverhulme Trust-Royal Society Africa award (AA090088). FM
thanks the University of the Philippines for the Faculty, Reps and
Staff Development Program (FRAS DP) PhD grant fellowship.
MHT and HD thank Leverhulme Trust research project (RPG-
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Legonoxamine A-B, two new hydroxamate
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Streptomyces sp. MA37
Leave this area blank for abstract info.
ab
a
a
c
a
Fleurdeliz Maglangit *, Ming Him Tong , Marcel Jaspars , Kwaku.Kyeremeh , Hai Deng **
a
Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland, UK
College of Science, University of the Philippines Cebu, Lahug, Cebu City, 6000, Philippines
b
c
Department of Chemistry, University of Ghana, P.O. Box LG56, Legon-Accra, Ghana
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Highlights:



Two new siderophores containing
phenylacetate motif were characterized
The putative biosynthetic gene cluster was
identified
Precursor-directed biosynthesis showed natural
flexibility for unnatural precursors.
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Barry SM, Challis GL. Curr Opin Chem Biol. 2009;