Structural and functional differences in two cyclic bacteriocins with the same sequences produced by lactobacilli

Yasushi Kawai, Yasuyuki Ishii, Kensuke Arakawa, Koichiro Uemura, Boku Saitoh, Junko Nishimura, Haruki Kitazawa, Yukiko Yamazaki, Yoshio Tateno, Takatoshi Itoh, Tadao Saito

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)


Lactobacillus gasseri LA39 and L. reuteri LA6 isolated from feces of the same human infant were found to produce similar cyclic bacteriocins (named gassericin A and reutericin 6, respectively) that cannot be distinguished by molecular weights or primary amino acid sequences. However, reutericin 6 has a narrower spectrum than gassericin A. In this study, gassericin A inhibited the growth of L. reuteri LA6, but reutericin 6 did not inhibit the growth of L. gasseri LA39. Both bacteriocins caused potassium ion efflux from indicator cells and liposomes, but the amounts of efflux and patterns of action were different. Although circular dichroism spectra of purified bacteriocins revealed that both antibacterial peptides are composed mainly of α-helices, the spectra of the bacteriocins did not coincide. The results of D- and L-amino acid composition analysis showed that two residues and one residue of D-Ala were detected among 18 Ala residues of gassericin A and reutericin 6, respectively. These findings suggest that the different D-alanine contents of the bacteriocins may cause the differences in modes of action, amounts of potassium ion efflux, and secondary structures. This is the first report that characteristics of native bacteriocins produced by wild lactobacillus strains having the same structural genes are influenced by a difference in D-amino acid contents in the molecules.

Original languageEnglish
Pages (from-to)2906-2911
Number of pages6
JournalApplied and environmental microbiology
Issue number5
Publication statusPublished - May 2004
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology


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