Biological Activities of Lasso Peptides and Structure–Activity Relationships - Lasso Peptides: Bacterial Strategies to Make and Maintain Bioactive Entangled Scaffolds - page 56

T able 3.2 (continued)

Pep des Producing bacteria Sensible bacteria

(MIC if known, in
µM) b

Insensible
microorganisms c

References

Caulobacter
crescentus
Caulobacter sp.
Caulobacter segnis
Sphingobium
japonicum,
Sphingopyxis
alaskensis
Xanthomonas
gardneri
Bacillus sub lis
Micrococcus flavus

No ac vity detected c Xanthomonins

I and II

Xanthomonas gardneri As caccaulis

excentricus
Burkholderia
thailendensis
Burkholderia
rhizoxinica
Caulobacter
crescentus
Caulobacter sp.
Caulobactersegnis
Sphingobium
japonicum
Sphingopyxis
alaskensis
Xanthomonas
gardneri
Bacillus sub lis
Micrococcus flavus

(Hegemann et al.
2014)

a Gram-posi ve bacteria, Gram-nega ve bacteria, and fungi are indicated in blue, red and
green, respec vely. n.d.: not reported.
b An bacterial assays and MIC measurements were performed from series dilu ons, using
either the agar diffusion method (S) or liquid cultures in microplates (L).
c As revealed by radial diffusion assay.
d The MIC values indicated correspond to laria n (termed ini ally laria n B) and its two
amino acid truncated variant (termed laria n A), respec vely.

Lasso peptides produced by actinobacteria are generally active against Gram-posi-
tive bacteria, while those produced by proteobacteria show a narrow spectrum of ac-
tivity directed against bacteria closely related to the producing strain. Propeptin and
aborycin constitute exceptions to this trend, being active on both Gram-positive and
Gram-negative bacteria such as Pseudomonas (Potterat et al. 1994 ; Kimura et al.
1997a ). Antimicrobial assays showed that propeptin (Kimura et al. 1997a ), capist-
ruin (Knappe et al. 2008 ) and astexin-1 (Maksimov et al. 2012 ) have only a weak
activity and no significant activity is noticed for anantin (Weber et al. 1991 ), sung-
sanpin (Um et al. 2013 ), caulosegnins (Hegemann et al. 2013 ) and xanthomonins
(Hegemann et al. 2014 ). This suggests either that the most sensible bacteria to these
lasso peptides have not been identified or that the antibacterial activity is in fact a
secondary function for lasso peptides, which could play another ecological role.