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1.
Ann Clin Microbiol Antimicrob ; 15(1): 43, 2016 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-27465344

RESUMO

BACKGROUND: Certain legume plants produce a plethora of AMP-like peptides in their symbiotic cells. The cationic subgroup of the nodule-specific cysteine-rich (NCR) peptides has potent antimicrobial activity against gram-negative and gram-positive bacteria as well as unicellular and filamentous fungi. FINDINGS: It was shown by scanning and atomic force microscopies that the cationic peptides NCR335, NCR247 and Polymyxin B (PMB) affect differentially on the surfaces of Sinorhizobium meliloti bacteria. Similarly to PMB, both NCR peptides caused damages of the outer and inner membranes but at different extent and resulted in the loss of membrane potential that could be the primary reason of their antimicrobial activity. CONCLUSIONS: The primary reason for bacterial cell death upon treatment with cationic NCR peptides is the loss of membrane potential.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Membrana Celular/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Proteínas de Plantas/farmacologia , Sinorhizobium meliloti/efeitos dos fármacos , Peptídeos Catiônicos Antimicrobianos/metabolismo , Membrana Celular/ultraestrutura , Medicago truncatula/fisiologia , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Proteínas de Plantas/metabolismo , Polimixina B/farmacologia , Nódulos Radiculares de Plantas/fisiologia , Sinorhizobium meliloti/crescimento & desenvolvimento , Sinorhizobium meliloti/ultraestrutura
2.
Gen Physiol Biophys ; 34(2): 135-44, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25675389

RESUMO

Antimicrobial peptides are small proteins that exhibit a broad spectrum of antimicrobial activity. Their chemical structure allows them to interact (attach and insert) with membranes. The fine details about this interaction and their mode of action are not fully clarified yet. In order to better understand this mechanism, we have performed in situ atomic force microscopy studies using two types of nodule specific cysteine-rich NCR peptides on Escherichia coli bacteria and on natural purple membrane. On intact bacteria, both NCR247 and NCR335 caused increase in the surface roughness, indicating the damage of the bacterial cell envelope. In case of the tightly packed purple membrane, it is clear that the peptides prefer to disrupt the border of the disks indicating a strong lipid preference of the interaction. These results verify the concept that the first target of NCR peptides is probably the bacterial cell envelope, especially the lipid matrix.


Assuntos
Peptídeos Catiônicos Antimicrobianos/química , Cisteína/química , Escherichia coli/química , Microscopia de Força Atômica/métodos , Mapeamento de Interação de Proteínas/métodos , Membrana Purpúrea/química , Sítios de Ligação , Ligação Proteica , Estresse Mecânico
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