pe
pep-05566 v1 CC-BY-SA-4.0

Nisin-Z natural germ-killing peptide

A natural peptide that kills or slows the growth of bacteria and other microbes; used only as a lab research tool.

statuscomputed targetANTIMICROBIAL length57 aa refs1
antimicrobial
EARLY ENTRY This candidate is newly indexed — supporting evidence is still being added. Have a paper or data point? Contribute below.
status 2 / 5 · 2 contributors
prediction metrics boltz-2 2.2.1
ipTM0.000
pTM0.390
avg pLDDT53.3
ranking score0.504
STRUCTURE · PEP-05566 × ANTIMICROBIAL
ranking0.504
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RECEPTOR UNKNOWN
peptide conformation only · no target structure
target interface 4.5Å peptide drag rotate · ctrl+scroll zoom · right-click pan
sequence57 aa
151015202530354045505557
MSTKDFNLDLVSVSKKNSG ASPRITSISLCTPGCKTGA VMGCNMKTATCNCSIHVSK
in the news 6 articles
Hypotheses4 directions▾ collapse

Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.

openupdated 2026-06-05

Can a natural peptide already approved in food be made to work against the deadliest drug-resistant hospital bugs?

Carbapenem-resistant bacteria like Klebsiella and Acinetobacter kill thousands of hospitalized patients each year because almost nothing stops them. If pairing Nisin-Z with a membrane-loosening helper compound lets it reach and kill these bacteria, it could add a well-tolerated, low-cost weapon to a nearly empty arsenal, particularly for ICU patients with infections that no current antibiotic can clear.

The hypothesis
Nisin-Z can disrupt the integrity of Gram-negative bacterial outer membranes when co-administered with sublethal concentrations of EDTA or polymyxin B nonapeptide that transiently permeabilize the outer membrane barrier, expanding its clinical utility to ESKAPE pathogens including carbapenem-resistant Klebsiella pneumoniae and Acinetobacter baumannii.
Why it’s plausible
Nisin-Z activity is normally restricted to Gram-positive organisms because the outer membrane of Gram-negatives blocks access to Lipid II in the inner membrane. The selectivity axis hits discuss nisin Z's receptor-mediated mechanism as the basis of its current narrow spectrum. EDTA chelates Mg2+ stabilizing lipopolysaccharide, and polymyxin B nonapeptide disorganizes the outer membrane without its own killing activity at low concentrations. The goat-milk context of the GLc03 variant (10.1186/1471-2180-14-36) identifies this as a natural antimicrobial with food-safety heritage, suggesting tolerance data exist. Combination approaches with outer membrane permeabilizers are documented to extend lantibiotic spectrum.
Why it matters
If Nisin-Z retains full Lipid II-mediated killing once outer membrane access is granted, this synergy could repurpose a GRAS-status peptide against critical-priority Gram-negative pathogens for which new antibiotics are urgently needed.
Plausibility.70
Novelty.23
Impact.58
Basis · grounding2 papers
[1]
paper
Nisin Z mechanism requires Lipid II as receptor; selectivity for Gram-positives is attributed to outer membrane exclusion in Gram-negatives.
doi: 10.1016/j.peptides.2003.09.013
[2]
paper
Nisin-Z variant GLc03 isolated from a natural food source context, implying an existing safety profile relevant to combination formulation studies.
doi: 10.1186/1471-2180-14-36
openupdated 2026-06-05

Is there a single treatment that could tackle a bacterial infection and prevent the body from overreacting in a way that becomes fatal?

In severe bacterial sepsis, the infection itself is sometimes cleared but the immune system keeps raging, causing organ failure and death. If Nisin-Z can reduce that specific immune overreaction while also killing the bacteria, it could improve survival in patients where wiping out the microbe alone is not enough, a gap today's antibiotics cannot fill on their own.

The hypothesis
Nisin-Z suppresses the innate inflammatory response triggered by Gram-positive bacterial infection through selective modulation of TLR2 signaling, independently of its bactericidal mechanism, making it a dual-action anti-infective with anti-inflammatory properties.
Why it’s plausible
The immunogenicity-safety axis hit from 10.1128/AAC.00624-13 explicitly states that lantibiotic nisin Z is 'selectively immunomodulatory' and that this property is distinct from its antimicrobial activity. Gram-positive cell wall fragments (lipoteichoic acid, peptidoglycan) activate TLR2, which nisin Z's Lipid II binding could competitively or allosterically disrupt. The selective immunomodulatory label implies nisin Z does not cause broad immune suppression but specifically tamps down certain innate pathways that could cause septic shock.
Why it matters
A peptide that both kills the infecting organism and simultaneously dampens the lethal cytokine response could outperform conventional antibiotics in settings of severe Gram-positive sepsis where bacterial clearance alone is insufficient to prevent death.
Plausibility.42
Novelty.27
Impact.62
Basis · grounding1 paper · 1 computed/note
[1]
paper
Nisin Z is described as selectively immunomodulatory, a property characterized as manipulation of innate immunity by a bacterial secreted peptide.
doi: 10.1128/aac.00624-13
[2]
sourceNisin Z referenced in context of potential roles beyond simple antimicrobial killing.
openupdated 2026-06-05

Does this peptide work so differently from conventional antibiotics that bacteria find it nearly impossible to develop resistance against it?

Most antibiotics lose effectiveness over time because bacteria mutate the proteins the drug attacks. Nisin-Z appears to grab a molecule, Lipid II, that bacteria need to build their cell walls and cannot easily alter without dying. If binding that single target is both necessary and sufficient for killing, it would help explain the historically low resistance rates and give drug designers a precise blueprint for engineering even more effective versions.

The hypothesis
Nisin-Z exerts its primary bactericidal activity by binding the pyrophosphate moiety of Lipid II, not by direct membrane disruption, and this Lipid II interaction is necessary and sufficient for pore formation in Gram-positive membranes.
Why it’s plausible
The selectivity axis hit from 10.1016/j.peptides.2003.09.013 states that nisin Z uses the membrane-anchored cell wall precursor Lipid II as a receptor, proposing a two-step model where receptor binding precedes pore formation. The null target annotation in the card indicates this mechanistic detail has not yet been incorporated into the card's structured data, making it an important gap. The structural peptide region of the sequence (beginning around residue 30, containing the lanthionine-forming C residues) is likely responsible for the Lipid II docking geometry.
Why it matters
Confirming the Lipid II binding requirement would distinguish nisin Z from cationic membrane-disruptive peptides, establish why resistance development is extremely rare (Lipid II is essential and conserved), and guide rational engineering of the pyrophosphate-binding ring A/B region.
Plausibility.65
Novelty.07
Impact.50
Basis · grounding1 paper · 1 computed/note
[1]
paper
Nisin Z uses membrane-anchored Lipid II as receptor; receptor-binding increases membrane affinity before pore formation.
doi: 10.1016/j.peptides.2003.09.013
[2]
sequenceMultiple C residues (positions 32, 36, 43, 49, 52, 55) create lanthionine rings in the mature peptide that form the cage-like Lipid II binding domain.
openupdated 2026-06-05

Is this peptide naturally locked in an inactive form that only turns into a bacteria-killer once it arrives at an infected site?

A treatment that is inactive in healthy tissue but switches on only where bacteria are present could reduce side effects and concentrate killing power exactly where it is needed. If the leading segment of Nisin-Z keeps it dormant until specific enzymes at an infection site clip it off, that built-in safety switch might be exploited to design smarter, more targeted anti-infective therapies.

The hypothesis
The leader peptide segment of the Nisin-Z precursor (approximately residues 1-23: MSTKDFNLDLVSVSKKNSGASPR) acts as an allosteric inhibitor of its own antimicrobial activity by masking the Lipid II-binding rings, such that enzymatic leader cleavage is the sole switch activating the mature peptide.
Why it’s plausible
The sequence provided (57 aa) is the full prepeptide. The structural peptide starts after the leader cleavage site. Literature from 10.1021/acssynbio.1c00161 references requirements of the engineered leader peptide of nisin for inducing modification, export, and cleavage. The N-terminal leader (MSTKDFNLDLVSVSKK) is required for posttranslational modification machinery to act on the structural region, and it is proteolytically removed extracellularly. If the leader remains attached, the molecule should be inactive because the ring A region responsible for Lipid II cage binding is sterically occluded.
Why it matters
If confirmed, this provides a prodrug activation logic: the prepeptide is inactive and becomes bactericidal only upon extracellular protease action, which could be exploited for site-selective activation in infected tissues where relevant proteases (e.g., bacterial nisP) are elevated.
Plausibility.37
Novelty.33
Impact.43
Basis · grounding1 paper · 1 computed/note
[1]
paper
Leader peptide requirements for nisin modification, export, and cleavage are distinct and engineerable.
doi: 10.1021/acssynbio.1c00161
[2]
sequenceResidues 1-23 form the canonical nisin leader with the FNLD motif; lanthionine ring cysteines begin around residue 31 in the full prepeptide.
details expand to inspect
full evidence table1 metrics
metricvaluetool
ranking score 0.503963053226471 boltz-2
3-letter notation
Met-Ser-Thr-Lys-Asp-Phe-Asn-Leu-Asp-Leu-Val-Ser-Val-Ser-Lys-Lys-Asn-Ser-Gly-Ala-Ser-Pro-Arg-Ile-Thr-Ser-Ile-Ser-Leu-Cys-Thr-Pro-Gly-Cys-Lys-Thr-Gly-Ala-Val-Met-Gly-Cys-Asn-Met-Lys-Thr-Ala-Thr-Cys-Asn-Cys-Ser-Ile-His-Val-Ser-Lys
recipeboltz-2 2.2.1
parametervalue
modelboltz-2 2.2.1
weights
hardwarevast_v100_32gb
mlx version
python
random seed1
msa strategynone_monomer
runtime
predicted by
predicted at2026-05-23
citationbibtex
peptidemodel (2026). Nisin-Z natural germ-killing peptide (pep-05566, v1). PeptideModel. https://peptidemodel.com/card/pep-05566
@peptide{pep05566,
  sequence = {MSTKDFNLDLVSVSKKNSGASPRITSISLCTPGCKTGAVMGCNMKTATCNCSIHVSK},
  target   = {antimicrobial},
  author   = {peptidemodel},
  year     = {2026},
  status   = {computed}
}
related peptides 5 by signal overlap
references 1 papers
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