New Series of BPL Inhibitors To Probe the Ribose-Binding Pocket of Staphylococcus aureus Biotin Protein Ligase

Article abstract of DOI:10.1021/acsmedchemlett.6b00248

Replacing the labile adenosinyl-substituted phosphoanhydride of biotinyl-5′-AMP with a N1-benzyl substituted 1,2,3-triazole gave a new truncated series of inhibitors of Staphylococcus aureus biotin protein ligase (SaBPL). The benzyl group presents to the

Full text of DOI:10.1021/acsmedchemlett.6b00248

Letter
pubs.acs.org/acsmedchemlett
New Series of BPL Inhibitors To Probe the Ribose-Binding Pocket of
Staphylococcus aureus Biotin Protein Ligase
Jiage Feng,†,‡ Ashleigh S. Paparella,§ William Tieu,†,∥ David Heim,§ Sarah Clark,† Andrew Hayes,§
Grant W. Booker,§ Steven W. Polyak,§ and Andrew D. Abell*,†,‡
§
‡
†Department of Chemistry, Department of Molecular and Cellular Biology, and Centre for Nanoscale BioPhotonics (CNBP),
University of Adelaide, Adelaide, South Australia 5005, Australia
S
* Supporting Information
ABSTRACT: Replacing the labile adenosinyl-substituted phosphoanhydride of biotinyl-5′-
AMP with a N1-benzyl substituted 1,2,3-triazole gave a new truncated series of inhibitors of
Staphylococcus aureus biotin protein ligase (SaBPL). The benzyl group presents to the
ribose-binding pocket of SaBPL based on in silico docking. Halogenated benzyl derivatives
(12t, 12u, 12w, and 12x) proved to be the most potent inhibitors of SaBPL. These
derivatives inhibited the growth of S. aureus ATCC49775 and displayed low cytotoxicity
against HepG2 cells.
KEYWORDS: Enzyme inhibitors, antibiotics, biotin protein ligase, Staphylococcus aureus
iotin protein ligase (BPL) catalyzes the reaction of biotin 1
B
and ATP 2 to give biotinyl-5′-AMP 3, which then
biotinylates and activates essential metabolic enzymes required
for fatty acid biosynthesis and gluconeogenesis, specifically
acetyl CoA carboxylase and pyruvate carboxylase (Figure 1).1−5
Figure 2. Reported BPL inhibitors, with isosteric replacements for the
phosphoanhydride of biotinyl-5′-AMP 3 shown in the box.
Figure 1. General mechanism of BPL catalyzed biotinylation.
Without exception, all isostere-based BPL inhibitors reported
to date contain a biotin and an adenine group, or analogue
thereof, as discussed above and as shown in Figure 2. These
two groups occupy well-defined binding pockets in the enzyme
as per biotinyl-5′-AMP 3, as supported by X-ray crystallo-
graphic and mutagenesis studies.3,16 The ribose group of the
triazole series can be removed as in 10, and the adenine can be
modified as in 11, which has improved stability and >1000-fold
specificity for the BPL from S. aureus over the human
homologue.3 We now report the first examples of truncated
1,2,3-triazole-based BPL inhibitors with a 1-benzyl substituent
A number of analogues of biotinyl-5′-AMP have recently been
reported as inhibitors of BPL as shown in Figure 2. Some of
these compounds have potential as antibacterial agents by
inhibiting BPL from clinically important pathogens such as
Staphylococcus aureus,6 Escherichia coli,7,8 and Mycobacterium
tuberculosis.9,10 A range of bioisosteres have been investigated as
replacements for the labile phosphoanhydride of biotinyl-5′-
AMP 3, including phosphodiester 4,11,12 hydroxyphosphonate
5,13 ketophosphonate 6,13 acylsulfamate 7,11 and sulphonmyl
amide 810 (Figure 2). We have also reported biotin triazoles
(e.g., 9−11) as a novel class of BPL inhibitor that selectively
targets BPL from the clinically important bacterial pathogen
Staphylococcus aureus over the human homologue.3,14,15
Received: June 26, 2016
Accepted: October 10, 2016
© XXXX American Chemical Society
A
DOI: 10.1021/acsmedchemlett.6b00248
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX

ACS Medicinal Chemistry Letters
Letter
designed to interact with the ribose binding pocket of S. aureus
BPL (SaBPL), see 12a−y, Figure 3. These derivatives are the
site can accommodate a variety of functional groups as
exemplified in the extended series depicted in Figure 3.
Synthesis and biological testing of this series provides an
opportunity to probe potential interaction with the ribose
pocket.
The synthesis of the 1,2,3-triazoles 12a−y was carried out as
summarized in Scheme 1. The key benzyl azides 14a−y were
a
Scheme 1
Figure 3. Benzyl-substituted 1,2,3-triazole analogues.
first examples of isostere-based BPL inhibitors lacking an
appended adenine or analogue thereof and the associated tether
as discussed above. The ribose-binding pocket is composed of
amino acids that provide potential hydrogen bonding sites,
specifically through the side chains of K187, R122, R125, and
R227 as well as the backbone peptide atoms from H126 and
S128 (Figure 4a). This series of inhibitors provides an
important starting point for further optimization and antibiotic
development.
a
Conditions and reagents: (a) (i) PPh3, CCl4, DMF; (ii) NaN3, DMF,
rt; (b) NaN3, DMF, rt; (c) Cu2SO4 ascorbate, DMSO/H2O, rt, 12 h
(give 12a−y (18%−55%)).
prepared from commercially available benzyl alcohols (13a−i
and 13n) and bromides (15j−m and 15o−y). Specifically,
commercially available benzyl alcohols 13a−i and 13n were
converted directly17 into the corresponding azides 14a−i and
14n on reaction with triphenylphosphine, in the presence of
carbon tetrachloride and sodium azide at ambient temperature.
The second series of benzyl azides (14j−m and 14o-y) was
prepared from commercially available benzyl bromides 15j−m
and 15o−y on reaction with sodium azide in DMF as shown.
Huisgen cycloaddition of biotin alkyne 1618 with each of the
benzyl azides 14a−y, in the presence of copper sulfate and
sodium ascorbate,3 then gave the desired 1,2,3-triazole 12a−y
as shown.
The activity profiles of 1,2,3-triazoles 12a−y were
determined using established biochemical and microbiological
assay protocols.3,19 Compounds displaying inhibitory activity
against SaBPL and cytotoxic activity against bacteria, but not
mammalian cells, are considered important candidates for
further antibiotic development. The in vitro potency and
selectivity profiles of the 1,2,3-triazoles 12a−y were measured
using recombinant BPLs from S. aureus and Homo sapiens. Here
the enzymatic incorporation of radiolabeled biotin onto an
acceptor protein was measured in the presence of varying
concentrations of each compound with the results shown in
Tables 1 and 2. Previous enzymology and X-ray crystallography
studies have demonstrated that the biotin triazoles are
competitive inhibitors against biotin,3,15,16 and as such,
inhibitory constants (Ki) were calculated from IC50 values
using the known KM for biotin as previously described.20 The
antibacterial activity of the compounds was also determined
using S. aureus strain ATCC 49775.18 Growth of the bacteria 20
h post-treatment was measured spectrophotometrically at 600
Figure 4. (a) X-ray structure of the SaBPL active site with biotinyl-5′-
AMP 3 (yellow) bound PDB ID 3RIR.10 Amino acids that encompass
the ribose-binding pocket are shown. Dashed lines represent hydrogen
bonds. (b) In silico docking poses for biotin triazole analogues 12a,
12b, and 12c containing a hydroxyl group at C2- (pink), C3- (blue),
and C4- (green), respectively.
In silico docking experiments were carried out in order to
explore possible binding modes by which this series of benzyl
analogues might occupy the active site of SaBPL. Flexible
ligand docking was carried out using AutoDockTools (version
1.5.6). The docking protocol was first validated by removing
compound 11 from its cocrystal structure with S. aureus BPL
(PDB 3V7S) and then redocking. This occurred with a high
degree of commonality as revealed by superimposition of the
docked and crystallized ligands in the active site. We next
docked benzylated triazoles 12a−c (Figure 3) into SaBPL.
Each of these structures contains a single hydroxyl substituent
on the benzyl ring capable of forming a hydrogen bond as per
the diol in the ribose of biotinyl-5′-AMP 3. Gratifyingly, the top
ranking poses of all three analogues placed the hydroxyl group
in the site occupied by the ribose diol of 3 (Figure 4a).
Rotation around the alkyl linker connecting the triazole and
benzyl moieties produced subtly different poses with regards to
the ribose-binding site (Figure 4b). These binding modes
minimized steric clashes with the protein and facilitated
hydrogen bonding between the alcohol group and R122 for
12a and R227 for 12b and 12c. This data reflects an apparent
openness of the solvent exposed pocket and suggests that this
B
DOI: 10.1021/acsmedchemlett.6b00248
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX

ACS Medicinal Chemistry Letters
Letter
and 0.56 μM, respectively), and these compounds provided
impetus for the expanded series of halogenated compounds
shown in Table 2 and as discussed in detail below. A strongly
electron withdrawing trifluoromethyl group at C3 and C4,
resulted in compounds (12l and 12m) that were devoid of
activity against SaBPL. All of the biotin triazoles tested were
inactive against human BPL when 100 μM of compound was
included in the assay medium. This is an important finding as it
demonstrates that benzyl truncated triazoles retain the
selectivity profile (i.e., active against S. aureus but not human
BPL) of the earlier and more complex triazoles.3,15
The compounds shown in Table 1 were also assayed for
antibacterial activity against S. aureus ATCC 49775. Com-
pounds were designated as antibacterial if they reduced the
optical density of the culture by >40% relative to the
nontreated controls (Figure 5). Of the 18 compounds assessed,
Table 1. In Vitro Biotinylation and Antibacterial Assay
Results for Benzyl Triazole Series 1
Ki SaBPL
(μM)
Ki human BPL
(μM)
anti-S. aureus
activity
a
ID
R
12a
12b
12c
12d
12e
12f
2-OH
3-OH
4-OH
2-OMe
3-OMe
4-OMe
2-NH2
3-NH2
4-NH2
3-Me
>10
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
>16
−
−
−
−
−
−
+
>10
1.59 0.08
0.53 0.05
1.17 0.1
>10
12g
12h
12i
1.48 0.14
>10
−
−
+
>10
12j
0.71 0.04
>10
12k
12l
4-Me
−
−
−
+
3-CF3
4-CF3
4-tBu
4-COOH
2-Br
>10
12m
12n
12o
12p
12q
12r
>10
1.22 0.07
0.67 0.06
0.96 0.13
>10
−
+
3-I
−
+
4-I
0.56 0.06
a
+, Optical density of the culture reduced by >40% of nontreated
controls. −, compound did not inhibit bacterial growth.
Table 2. In Vitro Biotinylation and Antibacterial Assay
Results for Benzyl Triazole Series 2
Ki SaBPL
(μM)
Ki Human
BPL (μM)
anti-S. aureus
cytotox
b
a
ID
R
activity
HepG2
12s
12t
2-F
>10
>16
>16
>16
>16
>16
>16
>16
−
+
N/D
>40
3-F
0.28 0.02
0.6 0.1
>10
12u
12v
12w
12x
12y
4-F
+
>40
2-Cl
3-Cl
4-Cl
3,4-diF
−
+
N/D
>40
0.39 0.04
1.1 0.07
>10
+
>40
−
N/D
a
+, optical density of the culture reduced by >40% of nontreated
b
controls. −, compound did not inhibit bacterial growth. Compounds
were assayed at 40 μg/mL.
nm. Finally, selected compounds were assessed for potential
toxicity using a cytotoxicity assay with cultured mammalian
HepG2 cells (ATCC HB-8065).3
Figure 5. Inhibition of S. aureus growth in vitro. (a) Compounds 12g
⧫
□
■
○
●
△
▼
( ), 12j ( ), 12p ( ), 12r ( ), 12t ( ), 12u ( ), 12w ( ), and 12x
▲
(
) were tested against S. aureus strain ATCC 49775. (b,c)
The initial series of alcohol analogues 12a−c docked against
SaBPL were first assayed against the enzyme (Table 1) with the
compound containing a C4 hydroxyl group (12c) showing
modest activity (Ki = 1.59 μM). Interestingly, the C2 and C3
hydroxylated derivatives (12a and 12b, respectively) were
devoid of activity. It thus appears that the ribose pocket is
sensitive to the position of the hydroxyl group and more so
than predicted by the modeling. This observation is supported
on analysis of the results for compounds containing other
substituents, although there is little consistency regarding which
position is most favored. Specifically, derivatives with a
methoxyl group at C2 and C3 were both active (12d, Ki =
0.53 μM; 12e, Ki = 1.1 μM), while the C4 analogue (12f) was
inactive. For an amino substituent, C2 is active (12g, Ki = 1.49
μM), while both C3 (12h) and C4 (12i) were inactive. Of the
other derivatives initially tested, C3 methyl (12j, Ki = 0.71 μM),
C4 carboxyl and tertiary butyl (12o, Ki = 0.67 μM; 12n, Ki =
1.1 μM) were active. The 2-bromo and 4-iodo derivatives 12p
and 12r showed good activity against S. aureus BPL (Ki = 0.96
Mechanism of action studies for 12g (b) and 12t (c). Growth curves
for S. aureus RN4220 harboring the plasmid pCN51 (open boxes,
negative control) or pCN51-BPL (solid boxes, for recombinant BPL
overexpression) are shown. Growth media contained 16 μg/mL of
compound, except, for no treatment controls (dashed line).
only five (those bearing amine, methyl, tertiary butyl, bromo,
and iodo substituents, see 12g, 12j, 12n, 12p, and 12r,
respectively) were active in the whole cell assays. The fact that
these compounds also inhibited SaBPL is consistent with a
mechanism of antibacterial action being through the BPL
target. It is possible that those BPL inhibitors devoid of whole
cell activity, namely, 12c−e, 12g, 12j, and 12p, are unable to
penetrate the bacterial membrane, a problem often encoun-
tered in antibacterial discovery.21
Of the extended halogenated series (12s−x in Table 2) four
compounds displayed good activity against SaBPL, see 12t,
12u, 12w, and 12x that had Ki values of 0.28, 0.6, 0.39, and 1.1
μM, respectively. A 3-halo substituent was most favored for
C
DOI: 10.1021/acsmedchemlett.6b00248
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX

ACS Medicinal Chemistry Letters
Letter
activity as in 12t and 12w. In these cases, the inhibition
constants were approximately 2- and 3-fold lower for the 3- vs
4- halogenated analogues, cf. 12t/12u and 12w/12x. A 3-fluoro
substituent (12t) provided the most potent compound in this
series with a Ki = 0.28 μM. The incorporation of a halogen at
C2 removed all activity (see 12s and 12v) as did the
introduction of a second fluoro substituent as in 12y. Again
all active compounds in this series showed excellent selectivity
for SaBPL over the human homologue. In addition, 12t, 12u,
12w, and 12x did not show cytotoxicity toward mammalian
HepG2 cells at a single concentration of 40 μg/mL.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acsmedchem-
lett.6b00248.
■
S
Biological assays, synthetic procedures, and data for
selected compounds (PDF)
AUTHOR INFORMATION
Corresponding Author
*Tel: +61 88 3135652. E-mail: andrew.abell@adelaide.edu.au.
■
Finally, to demonstrate that compounds inhibited protein
biotinylation in vivo, antibacterial susceptibility assays were
performed using a S. aureus strain engineered to overexpress the
BPL target. Similar approaches to establish the mechanism of
action have been employed on M. tuberculosis,10 but not
previously for S. aureus. Bacteria were grown in media
containing 16 μg/mL of either 12g (series 1) or 12t (series
2) for 16 h, with the optical density of the culture measured
every 30 min. Overexpression of the BPL target abolished the
antibacterial activity of both compounds, as S. aureus grew at
the same rate as nontreated controls (Figure 5b,c). Bacteria
harboring the parent cloning vector pCN5122 that did not
express additional BPL, remained highly sensitive to both
inhibitors and failed to grow in their presence. Together these
data show that the mechanism of action of 12g (from series 1)
and 12t (series 2) is clearly via the inhibition of BPL.
The 1-benzyl substituted 1,2,3-triazoles reported here
represent a new class of BPL inhibitors that lack the adenine
group, or analogue thereof, found in all other isostere-based
BPL inhibitors. These compounds have much reduced
molecular weight and are relatively easy to prepare.
Importantly, the biochemical and microbiological data provide
a clear relationship between in vitro inhibition of BPL and anti-
S. aureus activity, with our most potent enzyme inhibitors
generally providing our most promising antibacterials (see 12j,
12p, 12r, 12t, 12u, and 12w). In antibiotic drug discovery, this
is not always the case as a number of external factors contribute
to bioactivity, such as cell permeability and susceptibility to
efflux mechanisms and metabolic degradation.
The best lead compound in this new series (12t) with a 3-
fluoro substituted benzyl group, has a Ki of 280 nM against
SaBPL and demonstrated mechanism of antibacterial activity
consistent with the inhibition of protein biotinylation. It is
essentially nontoxic to mammalian HepG2 cells and is devoid
of activity against human BPL. This compares to the extended
1,2,3-triazole 11 that has Ki of 90 nM against SaBPL. This
compound provides clear interactions with both the biotin and
adenine pockets of SaBPL and, like the new benzyl series, is
essentially inactive against human BPL.3 Our initial SAR data
on the new benzyl series provides confidence that further
optimization of in vitro inhibition will lead to improved
antibacterial activity. In silico docking supports a binding
mechanism in which the benzyl group interacts with the ribose
pocket of SaBPL. The compounds reported here provide
important new scaffolds for further chemical modification and
activity optimization, specifically to interact with the adjacent
adenyl-binding site in the enzyme. Such studies are currently
underway, particularly the inclusion of extended substituents on
the benzyl group and also substitution at C5 of the triazole.
Present Address
∥School of Medical Sciences (Pharmacology) and Bosch
Institute, The University of Sydney, Sydney, New South
Wales 2006, Australia.
Author Contributions
The manuscript was written through contributions of all
authors. Medicinal chemistry was performed by J.F., W.T., S.C.,
and A.D.A., biochemical assays were performed by A.S.P. and
S.W.P., antibacterial susceptibility assays were performed by
D.H. and A.H. under the guidance of S.W.P. and G.W.B., and
cell culture assays were performed by A.H. and S.W.P.
Funding
This work was supported by the National Health and Medical
Research Council of Australia (application APP1068885), the
Centre for Molecular Pathology, University of Adelaide, and
Adelaide Research and Innovation’s Commercial Accelerator
Scheme. We are grateful to the Wallace and Carthew families
for their financial support of this work.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful to the Institute for Photonics and Advanced
Sensing (IPAS) for providing access to analytical HPLC and
the National Health and Medical Research Council (NHMRC)
and Australian Research Council (ARC) for funding. We also
thank Dr. Beatriz Blanco Rodriguez for her critical comments
on the manuscript.
REFERENCES
■
(1) Feng, J.; Paparella, A. S.; Booker, G. W.; Polyak, S. W.; Abell, A.
D. Biotin Protein Ligase Is a Target for New Antibacterials. Antibiotics
2016, 5 (3), 26.
(2) Duckworth, B. P.; Nelson, K. M.; Aldrich, C. C. Adenylating
enzymes in Mycobacterium tuberculosis as drug targets. Curr. Top. Med.
Chem. 2012, 12 (7), 766.
(3) Soares da Costa, T. P.; Tieu, W.; Yap, M. Y.; Pendini, N. R.;
Polyak, S. W.; Sejer Pedersen, D.; Morona, R.; Turnidge, J. D.;
Wallace, J. C.; Wilce, M. C.; Booker, G. W.; Abell, A. D. Selective
inhibition of biotin protein ligase from Staphylococcus aureus. J. Biol.
Chem. 2012, 287 (21), 17823−32.
(4) Pendini, N. R.; Bailey, L. M.; Booker, G. W.; Wilce, M. C.;
Wallace, J. C.; Polyak, S. W. Microbial biotin protein ligases aid in
understanding holocarboxylase synthetase deficiency. Biochim. Biophys.
Acta, Proteins Proteomics 2008, 1784 (7−8), 973−82.
(5) Polyak, S.; Abell, A.; Wilce, M.; Zhang, L.; Booker, G. Structure,
function and selective inhibition of bacterial acetyl-coa carboxylase.
Appl. Microbiol. Biotechnol. 2012, 93 (3), 983−992.
(6) Paparella, A. S.; Soares da Costa, T. P.; Yap, M. Y.; Tieu, W.;
Wilce, M. C.; Booker, G. W.; Abell, A. D.; Polyak, S. W. Structure
guided design of biotin protein ligase inhibitors for antibiotic
discovery. Curr. Top. Med. Chem. 2014, 14 (1), 4−20.
D
DOI: 10.1021/acsmedchemlett.6b00248
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX

ACS Medicinal Chemistry Letters
Letter
(7) Xu, Y.; Beckett, D. Kinetics of biotinyl-5′-adenylate synthesis
catalyzed by the Escherichia coli repressor of biotin biosynthesis and
the stability of the enzyme-product complex. Biochemistry 1994, 33
(23), 7354−7360.
(8) Brown, P. H.; Beckett, D. Use of binding enthalpy to drive an
allosteric transition. Biochemistry 2005, 44 (8), 3112−3121.
(9) Bockman, M. R.; Kalinda, A. S.; Petrelli, R.; De la Mora-Rey, T.;
Tiwari, D.; Liu, F.; Dawadi, S.; Nandakumar, M.; Rhee, K. Y.;
Schnappinger, D. Targeting Mycobacterium tuberculosis Biotin Protein
Ligase (MtBPL) with Nucleoside-Based Bisubstrate Adenylation
Inhibitors. J. Med. Chem. 2015, 58 (18), 7349−7369.
(10) Duckworth, B. P.; Geders, T. W.; Tiwari, D.; Boshoff, H. I.;
Sibbald, P. A.; Barry, C. E., 3rd; Schnappinger, D.; Finzel, B. C.;
Aldrich, C. C. Bisubstrate adenylation inhibitors of biotin protein
ligase from Mycobacterium tuberculosis. Chem. Biol. 2011, 18 (11),
1432−41.
(11) Brown, P. H.; Cronan, J. E.; Grøtli, M.; Beckett, D. The biotin
repressor: modulation of allostery by corepressor analogs. J. Mol. Biol.
2004, 337 (4), 857−869.
(12) Tieu, W.; Polyak, S. W.; Paparella, A. S.; Yap, M. Y.; Soares da
Costa, T. P.; Ng, B.; Wang, G.; Lumb, R.; Bell, J. M.; Turnidge, J. D.;
Wilce, M. C.; Booker, G. W.; Abell, A. D. Improved Synthesis of
Biotinol-5′-AMP: Implications for Antibacterial Discovery. ACS Med.
Chem. Lett. 2015, 6 (2), 216−20.
(13) Sittiwong, W.; Cordonier, E. L.; Zempleni, J.; Dussault, P. H.
beta-Keto and beta-hydroxyphosphonate analogs of biotin-5′-AMP are
inhibitors of holocarboxylase synthetase. Bioorg. Med. Chem. Lett.
2014, 24 (24), 5568−71.
(14) Tieu, W.; Jarrad, A. M.; Paparella, A. S.; Keeling, K. A.; Soares
da Costa, T. P.; Wallace, J. C.; Booker, G. W.; Polyak, S. W.; Abell, A.
D. Heterocyclic acyl-phosphate bioisostere-based inhibitors of Staph-
ylococcus aureus biotin protein ligase. Bioorg. Med. Chem. Lett. 2014, 24
(19), 4689−93.
(15) Tieu, W.; Soares da Costa, T. P.; Yap, M. Y.; Keeling, K. L.;
Wilce, M. C. J.; Wallace, J. C.; Booker, G. W.; Polyak, S. W.; Abell, A.
D. Optimising in situ click chemistry: the screening and identification
of biotin protein ligase inhibitors. Chem. Sci. 2013, 4, 3533−3537.
(16) Pendini, N. R.; Yap, M. Y.; Polyak, S. W.; Cowieson, N. P.;
Abell, A.; Booker, G. W.; Wallace, J. C.; Wilce, J. A.; Wilce, M. C.
Structural characterization of Staphylococcus aureus biotin protein ligase
and interaction partners: An antibiotic target. Protein Sci. 2013, 22 (6),
762−73.
(17) Koziara, A. A Facile, One-Pot Conversion of Primary Alcohols
into Amines. J. Chem. Res. (S) 1989, No. 9, 296−297.
(18) Soares da Costa, T. P.; Tieu, W.; Yap, M. Y.; Zvarec, O.; Bell, J.
M.; Turnidge, J. D.; Wallace, J. C.; Booker, G. W.; Wilce, M. C.; Abell,
A. D.; Polyak, S. W. Biotin analogues with antibacterial activity are
potent inhibitors of biotin protein ligase. ACS Med. Chem. Lett. 2012, 3
(6), 509−14.
(19) Polyak, S. W.; Chapman-Smith, A.; Brautigan, P. J.; Wallace, J.
C. Biotin Protein Ligase from Saccharomyces cerevisiae: The N-terminal
domain is required for complete activity. J. Biol. Chem. 1999, 274 (46),
32847−32854.
(20) Cheng, Y.; Prusoff, W. H. Relationship between the inhibition
constant (KI) and the concentration of inhibitor which causes 50%
inhibition (IC50) of an enzymatic reaction. Biochem. Pharmacol. 1973,
22 (23), 3099−108.
(21) Tommasi, R.; Brown, D. G.; Walkup, G. K.; Manchester, J. I.;
Miller, A. A. ESKAPEing the labyrinth of antibacterial discovery. Nat.
Rev. Drug Discovery 2015, 14 (8), 529−42.
(22) Charpentier, E.; Anton, A. I.; Barry, P.; Alfonso, B.; Fang, Y.;
Novick, R. P. Novel cassette-based shuttle vector system for gram-
positive bacteria. Appl. Environ. Microbiol. 2004, 70 (10), 6076−6085.
E
DOI: 10.1021/acsmedchemlett.6b00248
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX