Antimicrobial effects of H4-(86–100), histogranin and
related compounds – possible involvement of DNA gyrase
Simon Lemaire, Thuy-Tie
ˆ
n Trinh, Hoang-Thanh Le, Shun-Chii Tang, Maxwell Hincke,
Olivier Wellman-Labadie and Sophie Ziai
Department of Molecular and Cellular Medicine, University of Ottawa, Canada
Histones are highly conserved proteins that play a key
function in the packaging of DNA within eukaryotic
cells during their division [1]. Histone proteins and
fragments are also recognized to have some extra-
nuclear and extracellular functions [2]. Their anti-
microbial activity was first observed by Hirsch in 1958
[3], who reported that an arginine-rich preparation of
histones isolated from calf thymus (fraction B: a mix-
ture of histones H3 and H4) displayed potent bacterici-
dal activity mainly against Gram-negative bacteria, an
effect that was amplified by acid media, whereas
a lysine-rich preparation (fraction A: a mixture of
histones H1, H2A and H2B) was less effective. Since
then, a large body of evidence has indicated that
Keywords
antimicrobial peptide; DNA gyrase;
histogranin; histone H4 peptides; innate
immunity
Correspondence
S. Lemaire, Department of Cellular and
Molecular Medicine, Faculty of Medicine,
University of Ottawa, 451 Smyth Road,
Ottawa, ON, Canada K1H-8M5
Fax: +1 613 562 5434

Interestingly, the antimicrobial activities of H4-(86–100), HNr and com-
pound 3, like those of quinolone antibiotics acting as DNA gyrase poisons,
are potentiated by ATP (1 mm) and coumermycin A1 (a DNA gyrase-
linked ATPase inhibitor) and blocked by 2,4-dinitrophenol (DNP, an
uncoupler of oxidative phosphorylation) and fluoroacetic acid (a metabolic
poison). Finally, in vitro experiments indicate that H4-(86–100), HNr, com-
pound 3 and compound 8, but not HNb-(1–13) or HNb-(3–13), inhibit
DNA gyrase-mediated supercoiling of pBR322 DNA. These data indicate
that the naturally occurring H4-(86–100) and HNr display antimicrobial
effects that involve a modulation of ATP-dependent DNA gyrase.
Abbreviations
CFU, colony-forming unit; CFUv, virtual colony-forming unit; DNP, 2,4-dinitrophenol; HN, histogranin; HNb, bovine histogranin; HNr, rat
histogranin; NET, neutrophil extracellular trap; OGP, osteogenic growth peptide.
5286 FEBS Journal 275 (2008) 5286–5297 ª 2008 The Authors Journal compilation ª 2008 FEBS
histones H1, H2A and H2B are potent antimicrobial
agents [4–12]. Thus, antimicrobial histone H2A was
observed in skin exudates of rainbow trout [4], whereas
catfish skin [5] and salmon liver [6] extracts contained
antimicrobial histones H2B and H1, respectively. In
the toad stomach [7], histones H1, H2A and H2B were
observed in the cytoplasm of gastric gland cells along
with pepsinogen C, whereas the N-terminal his-
tone H2A fragment buforin-I formed a dense immuno-
reactive layer on the mucous surface of epithelial cells
[7]. The observation that pepsin C isozymes convert
histone H2A into buforin-I led the authors to propose
that histone-derived antimicrobial peptides may be
produced in the lumen of the stomach, where both
pepsinogen C and histone H2A are released, and there-
after histone H2A would be processed into buforin-I

nal medulla [14]. The immunoreactive peptide was
detected in various rat tissues, including the pituitary,
adrenal glands, lungs, spleen, brain and plasma [15].
Our initial search to determine the structure of the HN
gene led to the discovery of the H4-v.1 mRNA variant
in a bovine adrenal medulla cDNA library [16]. Bovine
H4-v.1 was shown to be a polyadenylated mRNA
coding for unmodified histone H4. The presence of
H4-v.1 mRNA in various rat tissues and isolated
alveolar macrophages correlated well with the presence
of immunoreactive H4-(86–100), but not whole his-
tone H4, suggesting a role for H4-v.1 mRNA in the
synthesis of the unmodified C-terminal histone H4
peptide [17]. More recently, the mRNA coding for rat
HN (HNr), a slightly modified fragment of H4-(86–
100), was also identified [18]. Interestingly, the levels of
both H4-v.1 and HN mRNAs in isolated rat alveolar
macrophages were increased in the presence of lipo-
polysaccharide. As the production of histone-derived
antimicrobial peptides in insects [19], trout [4] and
humans [11] is enhanced by lipopolysaccharide, and as
such induction at the bacterial trap sites (NETs) on
activated human neutrophils [12] is accompanied by
the release of ATP [13,20], it became of interest to
verify whether the histone H4-derived peptides H4-
(86–100) and HN possess bactericidal activity and
whether such activity is modified by ATP.
Herein we report that H4-(86–100), HN and related
compounds structure-dependently inhibit growth of
bacteria in an ATP-dependent quinolone-like manner,

bacteria.
The bactericidal potencies of H4-(86–100), HNr and
related peptides and nonpeptides in E. coli were com-
pared with those of the cationic peptides protegrin and
LL-37 (Table 2). Among the various HN-related
S. Lemaire et al. Antimicrobial histone H4 peptides
FEBS Journal 275 (2008) 5286–5297 ª 2008 The Authors Journal compilation ª 2008 FEBS 5287
peptides tested, H4-(86–100) displayed the highest
potency, with an LD
50
comparable to that of LL-37
(3.48 versus 4.1 lgÆmL
)1
). Protegrin was somewhat
more potent, with an LD
50
of 0.70 lgÆmL
)1
. H4-(86–
100) and HNr had close LD
50
values (4.34 and
3.48 lgÆmL
)1
). All fragments of HN and H4-(86–100),
including osteogenic growth peptide (OGP) or H4-(89–
102) [21], were much less potent than the parent
peptides, stressing the importance of the integrity of
the molecule (15 amino acids) for bactericidal activity.
However, the addition of Gly-Gly in the C-terminal

antimicrobial potency of HNb could be improved by
amidation of its C-terminal amino acid (LD
50
:
10.6 lgÆmL
)1
) or addition of Gly-amide (LD
50
:
15.3 lgÆmL
)1
).
HN-like cyclic tetrapeptides and nonpeptides were
recently designed to mimic the antinociceptive effects
of parent HN [22,23]. Among these compounds, com-
pounds 1–9 (Fig. 1C,D) contain basic, phenol and ⁄ or
phenyl groups that mimic key residues (Arg9, Tyr13
and Phe15) in HNr (Fig. 1B). As the opposite orienta-
tion of basic and hydrophobic amino acids in linear
amphipathic a-helical model peptides was shown to be
an important determinant for their antimicrobial activ-
ity [24], it was of interest to verify whether HN-like
compounds with similar structural arrangements
display antimicrobial activity. Table 2 indicates that
among the HN-like cyclic tetrapeptides, compound 3
[Fig. 1C: cyclo-(Gly-pCl-Phe-Tyr-d-Arg)] [22] is the
most potent E. coli-killing agent, with an LD
50
of
3.08 lgÆmL

the bacterial membrane through which they enter and
allow the entry and release of ions and other cell
constituents [26]. In most instances, the pores are
Table 1. Bactericidal activity of HNr and H4-(86–100) in Gram-nega-
tive and Gram-positive bacteria. Structures of HNr and H4-(86–100)
are illustrated in Fig. 1.
Compound
LD
50
± SEM
(lgÆmL
)1
)
LD
90
± SEM
(lgÆmL
)1
)
Escherichia coli (Gram-negative)
HNr 4.34 ± 0.39 10.33 ± 0.78
H4-(86–100) 3.48 ± 0.15 6.68 ± 0.73
Pseudomonas aeruginosa (Gram-negative)
HNr 3.50 ± 0.86 8.70 ± 1.32
H4-(86–100) 1.75 ± 0.03 4.80 ± 0.41
Bacillus subtilis (Gram-positive)
HNr 5.16 ± 0.84 14.06 ± 0.84
H4-(86–100) 5.16 ± 0.61 17.10 ± 2.43
Staphylococcus aureus (Gram-positive)
HNr > 30 > 30

*
HNb-(1–13) > 300
*
HNb-(3–13) > 300
*
HNb-(7–15) 16.25 ± 0.21
*
>30
*
HNb-(8–15) 150 ± 20
*
> 150
*
HNb-amide 10.6 ± 1.7
*
21.2 ± 2.8
HNb-Gly-amide 15.3 ± 2.8
*
22.5 ± 4.5
H4-(86–100) 3.48 ± 0.15
*
6.68 ± 0.73
*
H4-(86–102) 4.94 ± 0.94 17.7 ± 5.8
H4-(84–100) 26.25 ± 5.45
**
76.0 ± 17.2
**
H4-(84–102) 55.25 ± 1.77
**

*
> 300
*
Compound 7 117 ± 24
*
264 ± 18
*
Compound 8 13.90 ± 0.30
*
19.63 ± 2.25
Compound 9 180 ± 34
*
> 300
*
4. Reference peptides
LL-37 4.10 ± 0.44 6.93 ± 0.07
*
Protegrin 0.70 ± 0.10
*
1.00 ± 0.12
*
S. Lemaire et al. Antimicrobial histone H4 peptides
FEBS Journal 275 (2008) 5286–5297 ª 2008 The Authors Journal compilation ª 2008 FEBS 5289
short-lived and do not induce cell killing per se, but
they allow the entry of the cationic peptides into the
cells and their interaction with cytoplasmic polyanions,
nuclear proteins and DNA to induce bacteriostatic
and ⁄ or bactericidal activities [26,27]. We then pre-
sumed that the pores could also allow the entry of
ATP for potentiation of peptide activities. For

and fluoroacetic acid, a potent metabolic poison
(Fig. 3C,D), whereas coumermycin A1, a blocker of
Gyr-B-linked ATPase, enhanced their antimicrobial
activities (Fig. 3E,F).
Time dependence of the bactericidal activity of
H4-(86–100) and ciprofloxacin
In order to evaluate the rapidity of action of his-
tone H4 peptides and compare it with that of the
quinolone antibiotic ciprofloxacin, the LD
50
values of
Fig. 2. ATP potentiation of the bactericidal
activity of H4-(86–100) (A), HNr (B), com-
pound 3 (C) and ciprofloxacin (D) against
E. coli. LL-37 (E) and protegrin (F) were
used as negative controls. LD
50
and LD
90
values are expressed in lgÆmL
)1
.*P £ 0.05
as compared to control.
Antimicrobial histone H4 peptides S. Lemaire et al.
5290 FEBS Journal 275 (2008) 5286–5297 ª 2008 The Authors Journal compilation ª 2008 FEBS
H4-(86–100) and ciprofloxacin were measured after dif-
ferent periods (15 min, 30 min and 2 h) of incubation
in phosphate buffer at 37 °C with E. coli (Fig. 4). The
bactericidal effects of H4-(86–100) and ciprofloxacin
were completed within 30 min, as incubation of the

The observation that the antimicrobial effects of H4-
(86–100), HNr and the compound 3, like those of the
quinolone class of antibiotics acting on DNA gyrase,
are potentiated by ATP and modulated by chemical
agents that affect cell levels of ATP led us to verify the
effects of HN and related compounds on the in vitro
supercoiling activity of DNA gyrase (Fig. 6). Both
HNr (Fig. 6A) and H4-(86–100) (data not shown)
inhibited supercoiling of pBR322 DNA in a dose-
dependent manner, total inhibition being observed
with 5–7 lgÆ20 lL
)1
assay. Inhibition of DNA gyrase
supercoiling activity was also observed with the potent
antimicrobial compounds 3 and 8, but not bovine
histogranin (HNb)-(1–13) or HNb-(3–13) (Fig. 6B),
two inactive HN fragments, in the antimicrobial assay
Fig. 3. Effects of the uncoupler of
oxidative oxidation DNP (A, B), the
aconitase inhibitor fluoroacetate (C, D) and
the inhibitor of DNA gyrase-linked ATPase,
coumermycin A1 (E, F) on the bactericidal
activity of H4-(86–100) and ciprofloxacin
against E. coli.LD
50
is expressed in
lgÆmL
)1
.*P £ 0.05 as compared with
control.

linear amphipathic peptides without cysteine. Most of
these short antimicrobial peptides have random struc-
tures in water [27]. In this regard, H4-(86–102) dis-
solved in water displayed the characteristics of a fully
random conformation [29]. However, antimicrobial
peptides are known to form a structure, namely the
a-helical structure, when they bind to a membrane or
another hydrophobic cellular organelle [30,31]. His-
tone H4 contains two a-helical regions. One region
spans amino acids 55–67 [32]. A second region, that
spans amino acids 70–90, has been demonstrated to
adopt the a-helical conformation when histone H4 is
associated with the nucleosome but not when purified
histone H4 polymerizes in solution [29]. Thus, the pos-
sibility that extracellular HNr and its related peptide
H4-(86–100) form a-helical structures pertains to their
ability to associate with plasma membranes and other
hydrophobic cellular organelles. The theoretical helical
wheel conformation of HNr shows the basic and
hydrophobic or neutral amino acids on opposite sur-
faces of the molecule (Fig. 1B). Such an arrangement
of basic and hydrophobic groups was reported to be a
good prediction factor for the antimicrobial activity of
model [24] and naturally occurring cationic peptides
[33]. Some members of this group, such as buforin-II
[33,34], which act rapidly without any lag time, are
believed to kill bacteria by penetrating their membrane
and binding to the DNA without inducing cell lysis. In
the present study, HNr and H4-(86–100), like the
quinolone antibiotic ciprofloxacin, displayed rapid

antimicrobial agents that act by an inhibition of DNA
gyrase. Their antimicrobial effects in vivo are blocked
by drugs such as DNP and fluoroacetate, which are
known to lower cell levels of ATP [23]. Similarly,
in vitro, their inhibitory effects on gyrase-mediated
DNA catenation are potentiated by the presence of
ATP [28]. In order to verify whether H4-(86–100) and
related compounds affect bacterial cell growth by a
mechanism that involves modulation of DNA gyrase
activity, we first verified whether the antimicrobial
activities of the peptides were affected by the presence
of DNP or fluoroacetate. The two agents significantly
blocked the antimicrobial activity of H4-(86–100)
(Fig. 3A,C), whereas the presence of coumermycin A1,
an inhibitor of DNA gyrase-linked ATPase, enhanced
its antimicrobial activity (Fig. 3E). Thus, agents that
decrease cellular levels of ATP inhibit the antimicro-
bial activity of HN-like peptides, whereas coumermy-
cin A1, which may increase cellular levels of ATP by
its inhibition of DNA gyrase-linked ATPase, enhances
their activity. Interestingly, similar observations were
obtained with the potent quinolone antibiotic cipro-
floxacin (Fig. 3B,D,F).
More direct support for the involvement of DNA
gyrase in the antimicrobial effects of H4-(86–100) and
related compounds was obtained in vitro by the mea-
surement of their inhibitory activity on the supercoiling
of pBR322 plasmid induced by the commercially avail-
able DNA gyrase holoenzyme (Topogen) (Fig. 6). In
this assay, the inhibitory effects of the potent anti-

)1
) and to kill bacte-
ria (3–4 lgÆmL
)1
) may be due to the greater ability of
antimicrobial peptides to adopt the a-helical conforma-
tion in a hydrophobic cell-containing milieu than in an
aqueous cell-free DNA gyrase assay [30,31].
Histones are known to possess domains that bind to
other histones and other nuclear proteins, and domains
that bind to DNA to form the nucleosome. In his-
tone H4, the C-terminal segment that corresponds to
H4-(86–100) or HN is the portion of the molecule that
binds to other histones and ⁄ or proteins, whereas the
N-terminal segment has the ability to bind to DNA
according to its acetylation and methylation status
[29]. The possibility that HN and H4-(86–100) bind to
DNA gyrase to inhibit its activity is a subject that
merits our attention. The site of action of quinolone
antibiotics has been determined to be on the gyrA sub-
unit of the enzyme, due to the ability of the mutation
of Ser83 to Trp to induce resistance and affect quino-
lone binding to the gyrase–DNA complex [35]. How-
ever, histone H4-derived peptides and HN would be
expected to be devoid of resistance induction, due to
the evolutionary stability of histones, and more partic-
ularly histone H4 [32]. Interestingly, mutations at
codon 751 of the E. coli gyrB gene conferred resistance
to the antimicrobial peptide microcin B17 [36]. As
H4-(86–100) and HN are peptides that display

compounds were cleaved from the resin and purified by
passage through Sephadex G-10, Sep-Pak cartridges
(Waters) and semipreparative HPLC columns (l-bondapak
C18; Waters). The purity of the products was verified by
TLC (one spot, ninhydrin detection) and analytical HPLC
on l-bondapak C-18 columns (Waters). Their identity was
A
B
C
D
Fig. 6. Inhibitory effects of various concentrations of HNr (A),
7 lgÆ20 lL
)1
of H4-(86–100), OGP, compound 3, compound 8,
HNb-(3–13) and HNb-(1–13) (B) and 3 lgÆ20 lL
)1
of HNr, coumer-
mycin A1, ciprofloxacin, LL-37 and ampicillin (C) on DNA gyrase-
mediated pBR322 supercoiling. The DNA gyrase supercoiling assay
was carried out with the Topogen assay kit as described in Experi-
mental procedures using relaxed pBR322 plasmid as the substrate.
R, relaxed pBR322; S, supercoiled pBR322; SS, standard super-
coiled pBR322. In order to verify whether the various compounds
interacted directly with the DNA, the effects of 3 lgÆ20 lL
)1
of H4-
(86–100), HNr, coumermycin A1 (Cou), ciprofloxacin (Cip), LL-37
and ampicillin (Amp) on the migration of SS in the absence of the
enzyme was also monitored (D).
Antimicrobial histone H4 peptides S. Lemaire et al.

ClN
7
O
5
, calculated 559.0).
Bactericidal assays
Microwell turbidimetric procedure
Cultures were grown overnight in LB media with shaking
(250 r.p.m.). On the next day, the cultures were diluted 1 : 50
in the same medium and incubated for an additional 2 h to
obtain the cells in the midlogarithmic phase. They were then
diluted in 10 mm sodium phosphate buffer (pH 7.4) at
6.1 million virtual colony-forming units (CFUv)ÆmL
)1
(vir-
tual colony counting) [25]. Cells (35 lL) were preincubated
for 2 h or (as indicated in Fig. 4) at 37 °C with shaking
(250 r.p.m.) in microwells in the absence or presence of vari-
ous concentrations (from 0.5 to 300 lgÆmL
)1
) of HN and
related compounds in a total volume of 50 lL. In some
experiments, the inhibitory effects of H4-(86–100), HNr or
compound 3 on cell growth were modulated by the addition
to the preincubation media of ATP (1 mm), DNP (an uncou-
pler of oxidative phosphorylation; 2 mm), fluoroacetic acid
(an aconitase inhibitor; 4 mm) or coumermycin A1 (an ATP-
antagonizing gyrase poison; 2 lm). Serial dilutions of the
cells (1.0, 0.5, 0.1, 0.05, 0.01 and 0.005 · 10
6

the mean ± SEM of three duplicated sets of experiments.
Statistical significance was determined using one-way analy-
sis of variance followed by a Bonferonni comparison test.
P £ 0.05 is considered as significant.
Radial diffusion assay
The radial diffusion assay of Steinberg & Lehrer [37] was
used to confirm the antimicrobial activity of H4-(86–100)
and related compounds. B. subtilis bacteria were grown to
log phase in LB broth, centrifuged at 1000 g for 15 min,
and resuspended in 10 mm sodium phosphate buffer
(pH 7.3) (1 · 10
5
CFUÆmL
)1
). Molten culture medium
(1.5% low-electroendosmosis agarose, 1% biotryptone,
0.5% yeast extract; Bioshop, Burlington, Canada) was
prepared in 10 mm sodium phosphate buffer. The medium
was distributed into culture Petri dishes and allowed to
solidify. The gel surface was inoculated by the addition of
5 mL of the bacterial preparation, which was immediately
removed. Test compounds (50 lgin10lL of phosphate
buffer) were applied to Whatman No. 1 paper disks (6 mm
in diameter). After the solvent had been allowed to evapo-
rate for 1 h at room temperature, disks were applied to
bacterial plates. Disks treated with the phosphate buffer or
0.2 lg of ciprofloxacin in the phosphate buffer were used as
negative and positive controls. Following the application of
sample disks, plates were incubated at 37 °C for 18 h. The
antimicrobial activities of the compounds were assessed by

6 Richards RC, O’Neil DB, Thibault P & Ewart KV
(2001) Histone H1: an antimicrobial protein of Atlantic
salmon (Salmo salar). Biochem Biophys Res Commun
284, 549–555.
7 Kim HS, Yoon H, Minn I, Park CB, Lee WT, Zasloff
M & Kim SC (2000) Pepsin-mediated processing of the
cytoplasmic histone H2A to strong antimicrobial pep-
tide buforin I. J Immunol 165, 3268–3274.
8 Li GH, Mine Y, Hincke MT & Nys Y (2007)
Isolation and characterization of antimicrobial pro-
teins and peptide from chicken liver. J Pept Sci 13,
368–378.
9 Silphaduang U, Hincke MT, Nys Y & Mine Y (2006)
Antimicrobial proteins in chicken reproductive system.
Biochem Biophys Res Commun 340, 648–655.
10 Rose FR, Bailey K, Keyte JW, Chan WC, Greenwood
D & Mahida YR (1998) Potential role of epithelial cell-
derived histone H1 proteins in innate antimicrobial
defense in the human gastrointestinal tract. Infect
Immun 66, 3255–3263.
11 Kim HS, Cho JH, Park HW, Yoon H, Kim MS &
Kim SC (2002) Endotoxin-neutralizing antimicrobial
proteins of the human placenta. J Immunol 168, 2356–
2364.
12 Brinkmann V, Reichard U, Goosmann C, Fauler B,
Uhlemann Y, Weiss DS, Weinrauch Y & Zychlinsky A
(2004) Neutrophil extracellular traps kill bacteria.
Science 303, 1532–1535.
13 Elzschig HK, Eckle T, Mager A, Kuper N, Karcher C,
Weissmuller T, Boengler K, Shulz R, Robson SC &

19 Hetru C, Hoffmann D & Bulet P (1998) Antimicrobial
peptides from insects. In Molecular Mechanisms of
Immune Responses in Insects (Brey PT & Hultmark D,
eds), pp. 40–66. Chapman & Hall, London.
20 Bours MJL, Swennen ELR, Di Virgilio F, Cronstein
BN & Dagnelie PC (2006) Adenosine 5¢-triphosphate
and adenosine as endogenous signaling molecules in
immunity and inflammation. Pharmacol Therapeut 112,
358–404.
21 Bab I, Gazit D, Chorev M, Muhlrad A, Shteyer A,
Greenberg Z, Namdar M & Kahn A (1992) His-
tone H4-related osteogenic growth peptide (OGP): a
novel circulating stimulator of osteoblastic activity.
EMBO J 11, 1867–1873.
22 Le HT, Lemaire I, Gilbert AK, Jolicoeur F & Lemaire
S (2003) Bioactive peptidic analogues and cyclostereoi-
somers of the minimal antinociceptive histogranin frag-
ment-(7–10). J Med Chem 46, 3094–3101.
23 Le HT, Lemaire IB, Gilbert AK, Jolicoeur F, Yang L,
Leduc F & Lemaire S (2004) Histogranin-like antinoci-
ceptive and anti-inflammatory derivatives of o-phenyl-
enediamine and benzimidazole. J Pharmacol Exp Ther
309, 146–155.
24 Blondelle SE & Houghten RA (1992) Design of model
amphipathic peptides having potent antimicrobial activ-
ities. Biochemistry 31, 12688–12694.
25 Ericksen B, Wu Z, Lu W & Lehrer RI (2005) Anti-
bacterial activity and specificity of the six human
b-defensins. Antimicrob Agents Chemother 49, 269–275.
26 Hancock RE & Scott MF (2000) The role of anti-

antimicrobial peptides magainin and buforin
across human cell membranes. J Biol Chem 278,
1310–1315.
35 Willmott CJR & Maxwell A (1993) A single point
mutation in the DNA gyrase A protein greatly
reduces binding of fluoroquinolones to the
gyrase–DNA complex. Antimicrob Agents Chemother
37, 126–127.
36 Del Castillo F, Del Castillo I & Moreno F (2001) Con-
struction and characterization of mutations at
codon 751 of the Escherichia coli gyrB gene that confer
resistance to the antimicrobial peptide microcin B17
and alter the activity of DNA gyrase. J Bacteriol 183,
2137–2140.
37 Steinberg DA & Lehrer RI (1997) Designer assays for
antimicrobial peptides. Disputing the one-size-fits-all
theory. Methods Mol Biol 78, 169–186.
38 Mizuuchi K, Mizuuchi M, O’Ddea MH & Gellert M
(1984) Cloning and simplified purification of Escherichia
coli DNA gyrase A and B proteins. J Biol Chem 259,
9199–9201.
S. Lemaire et al. Antimicrobial histone H4 peptides
FEBS Journal 275 (2008) 5286–5297 ª 2008 The Authors Journal compilation ª 2008 FEBS 5297