title: Solution structure of acidocin B, a circular bacteriocin produced by Lactobacillus acidophilus M46.
abstract: Acidocin B, a bacteriocin produced by Lactobacillus acidophilus M46, was originally reported to be a linear peptide composed of 59 amino acid residues. However, its high sequence similarity to gassericin A, a circular bacteriocin from Lactobacillus gasseri LA39, suggested that acidocin B might be circular as well. Acidocin B was purified from culture supernatant by a series of hydrophobic interaction chromatographic steps. Its circular nature was ascertained by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and tandem mass spectrometry (MS/MS) sequencing. The peptide sequence was found to consist of 58 amino acids with a molecular mass of 5,621.5 Da. The sequence of the acidocin B biosynthetic gene cluster was also determined and showed high nucleotide sequence similarity to that of gassericin A. The nuclear magnetic resonance (NMR) solution structure of acidocin B in sodium dodecyl sulfate micelles was elucidated, revealing that it is composed of four α-helices of similar length that are folded to form a compact, globular bundle with a central pore. This is a three-dimensional structure for a member of subgroup II circular bacteriocins, which are classified based on their isoelectric points of ∼7 or lower. Comparison of acidocin B with carnocyclin A, a subgroup I circular bacteriocin with four α-helices and a pI of 10, revealed differences in the overall folding. The observed variations could be attributed to inherent diversity in their physical properties, which also required the use of different solvent systems for three-dimensional structural elucidation.
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Jeella Z
authors: JZ
authors: Acedo
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Marco J
authors: MJ
authors: van Belkum
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Christopher T
authors: CT
authors: Lohans
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Ryan T
authors: RT
authors: McKay
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
authors: Mark
authors: M
authors: Miskolzie
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada john.vederas@ualberta.ca.
authors: John C
authors: JC
authors: Vederas
mesh_terms: D000595:Amino Acid Sequence; D001430:Bacteriocins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018360:Crystallography, X-Ray; D007779:Lactobacillus acidophilus / Q000235:genetics* / Q000378:metabolism; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D001430:Bacteriocins; C090262:acidocin B protein, Lactobacillus