Streptococcus mutans strain N produces a novel low molecular mass non-lantibiotic bacteriocin

Abstract

Streptococcus mutans strain N was shown to have bacteriocin production and immunity characteristics consistent with those of Group I mutacin-producing strains of S. mutans. The bacteriocin mutacin N was purified from agar cultures of S. mutans strain N using XAD and reversed phase chromatography. The molecular mass of mutacin N was 4806 Da and the entire 49 amino acid sequence was determined by N-terminal sequencing. Database searches indicate that mutacin N is a novel bacteriocin, but with some homology to the protein IIC domain of a hypothetical sugar-phosphotransferase enzyme from Acholeplasma florum. ß

Bacteriocin (Mutacin) Production by Streptococcus mutans Genome Sequence Reference Strain UA159: Elucidation of the Antimicrobial Repertoire by Genetic Dissection

“…In contrast, inactivation of nlmB did not appear to affect inhibitory activity against the same 66 strains ( Table 1). The above observations were corroborated when selected strains were tested by a modification of the standard deferred antagonism assay (2) in which the number of producer cells inoculated was standardized (15-l drop inoculum of an 18-h Todd-Hewitt broth culture adjusted to an optical density at 600 nm of 0.02). No significant differences in the sizes of inhibitory zones were detected between wild-type UA159 and the nlmB mutant UA⌬NlmB (Table 3).…”

“…The bacteriocins produced by the oral bacterium Streptococcus mutans are termed mutacins and are divided into two groups: (i) the lanthionine-containing (lantibiotic) mutacins (6,11,16,19,20) and (ii) the unmodified mutacins (2,21). While most bacteriocin activities characterized to date consist of a single active polypeptide, several two-component lantibiotic and nonlantibiotic bacteriocins have also been described, and these are dependent upon the collaborative activity of two polypeptides to exert their full antimicrobial activity (7,9,14,15,17,23).…”

Identification of nlmTE , the Locus Encoding the ABC Transport System Required for Export of Nonlantibiotic Mutacins in Streptococcus mutans

“…The inhibitory spectrum of mutacin N is distinctive compared to that of other mutacins in its ability to inhibit certain S. mutans strains (3,4). The resulting nlmT-deficient mutant, N⌬NlmT, failed to express any inhibitory activity ( Table 2), indicating that the NlmTE ABC transporter is also required for nonlantibiotic mutacin export in S. mutans strain N.…”

Different bacteriocin activities of Streptococcus mutans reflect distinct phylogenetic lineages

“…The N-terminal sequence of mutacin N (group A) indicates that this peptide does not contain lanthionine or â-methyl lanthionine and that it has a strong match to a putative sugar-phosophotransferase enzyme from Acholeplasma florum [25]. One component of the non-lantibiotic bacteriocin mutacin IV [24] purified from strain UA140 (group A in the present study) shows a high degree of similarity to mutacin N despite the fact that the producing strains appear to be phylogenetically distinct.…”

“…More recently, this group has reported that the group I S. mutans strain UA140 produces, in addition to mutacin I, a twocomponent non-lantibiotic bacteriocin named mutacin IV [24]. Interestingly, the NlmB component of mutacin IV shares partial homology with mutacin N [25].…”