Elucidation of the structure of SA‐FF22, a lanthionine‐containing antibacterial peptide produced by Streptococcus pyogenes strain FF22

Abstract

The antibacterial peptide SA-FF22, produced by the pathogen Streptococcus pyogenes strain FF22 was purified and features of its primary and secondary structure were characterised. Mass spectrometry demonstrated the pure peptide had a mass of 2794Da while, amino acid analysis revealed the presence of the unusual, thioether amino acids lanthionine and 3-methyllanthionine ; thus SA-FF22 is a member of the group of antibacterial polypeptides termed lantibiotics. Furthermore, amino acid sequencing showed a unique sequence which was blocked at position 23 by a residue of the unsaturated amino acid 2,3-didehydrobutyrine. Carboxypeptidase-Y digestion could be used to demonstrate that serine occupies the C-terminal position only after complete oxidation of the thioether amino acid bridges, suggesting that the three-dimensional structure of the native peptide may prevent access of the enzyme to the C-terminus. Fragmentation of the native peptide with a variety of proteolytic enzymes failed to yield a peptide containing less than all three of the cross-linked lanthionine and methyllanthionine residues and demonstrated that all three thioether bridges overlapped. Analysis of the circular dichroism of SA-FF22 in various concentrations of 2,2,2-trifluoroethanol in water, SDS micelles and in the presence of artificial phospholipid vesicles suggested that there is significant change in its secondary structure from aqueous to lipophilic environments.SA-FF22 is a bacteriocin-like inhibitory substance produced by Streptococcus pyogenes strain FF22 and which has been shown to be bactericidal for many strains of related streptococci [l]. Subsequent to its discovery, SA-FF22 was partially purified and characterised [2, 31. In these initial studies it was demonstrated that the inhibitory factor contained an essential proteinaceous component since it was inactivated by several proteolytic enzymes, was of approximately 8000Da as determined by dialysis and gel filtration, was stable in acid solution and at high temperatures but was not stable under alkaline conditions and was active against only certain Gram-positive bacteria. Further studies showed that the genetic determinant(s) that controlled SA-FF22 production appeared to be lost spontaneously in aged cultures or through the use of plasmid 'curing' agents, suggesting that SA-FF22 production was encoded on a plasmid. AdditionCorrespondence to R. W. Jack,

The structure of the lantibiotic lacticin 481 produced by Lactococcus lactis: location of the thioether bridges

“…nisin, actagardine and epilancin K7) NMR can be applied directly, while for the lacticin-481 type lantibiotics chemical modification is necessary prior to NMR analysis. A similar CNBr reaction as used for lacticin 481 can be applied for variacin, while SA-FF22 can be cleaved within the overlapping ring systems as shown before [32].…”

“…Lacticin 481 has been classified as type A [5]. Both the lantibiotic and the leader sequence of lacticin 481 show significant homology to the corresponding sequences of the lantibiotics streptococcin A-FF22 (SA-FF22) [31,32], salivaricin A [33] and variacin [34] (see Fig. 6), but not to those of the other type-A lantibiotics [5,30].…”

Mekanisme Awal dan Aplikasi Antibakteri Pediosin PaF-11 Sebagai Pengawet Tahu

“…Pada mekanisme ini, bakteriosin teradsorpsi oleh bakteri yang rentan pada reseptor yang spesifik, selanjutnya terjadi perubahan permeabilitas dan integritas membran menyebabkan sel kehilangan kemampuannya untuk membelah diri dan terjadi lisis 7 . Komponen molekul anion pada permukaan bakteri Gram positif yang berperan penting dalam interaksi awal bakteriosin bermuatan positif (kation) dengan sel indikator adalah asam teikoat dan asam lipoteikoat 7,8 . dapat menempel pada muatan negatif dari kelompok permukaan fosfolipid dalam membran sitoplasma dan dapat menghalangi interaksi elektrostatik antara pediosin dan lipid anion 11 .…”

“…Berdasar kajian pustaka bahwa ion logam positif Gd 3+ mengikat muatan negatif reseptor 10,20 dan komponen molekul anion pada permukaan bakteri Gram positif yang berperan penting dalam interaksi awal bakteriosin bermuatan positif (kation) dengan sel indikator adalah asam teikoat dan asam lipoteikoat 7,8 serta mekanisme penghambatan pediosin AcH terhadap Listeria diawali dengan interaksi antara pediosin AcH dengan asam lipoteikoat atau asam teikoat 8 maka hipotesis yang diajukan yaitu bahwa mekanisme awal penghambatan pediosin PaF-11 sebagai antibakteri adalah melalui interaksi pediosin PaF-11 dengan asam lipoteikoat dan asam teikoat. Selanjutnya, berdasar karakteristik pediosin PaF-11 yang bersifat antibakteri terhadap bakteri pembusuk dan stabil pada suhu tinggi dan rendah serta pH yang luas, maka hipotesa kedua yaitu bahwa pediosin PaF-11 mampu menghambat bakteri dalam tahu dipasteurisasi dan disimpan dingin (4 o C) dan memperpanjang masa simpannya.…”

“…Hal ini menunjukkan bahwa gadolinium menurunkan aktivitas pediosin PaF-11 dan nisin dalam menghambat pertumbuhan L. pentosus LB42. Hasil ini mengindikasikan bahwa penambahan gadolinium diduga menetralkan muatan negatif reseptor asam teikoat dan asam lipoteikoat 7,8 26 . Diketahui bahwa pediosin PaF-11 mengandung sejumlah asam amino hidrofobik sebagai berikut : metionin, isoleusin, leusin, alanin, tirosin, valin, dan triptofan 26 .…”