Substrate selectivity of the sublancin S-glycosyltransferase.

J Am Chem Soc. 2011 Oct 19;133(41):16394-7

Authors: Wang H, van der Donk WA

Abstract
SunS is a novel S-glycosyltransferase involved in the biosynthesis of the antimicrobial peptide sublancin. It selectively modifies Cys22 in a 56 amino acid peptide substrate SunA and can accept a variety of NDP sugars. This study reports the substrate selectivity with regard to the peptide substrate and the antimicrobial activity of the resulting sublancin analogues. The results suggest that SunS recognizes an ?-helix N-terminal of the Cys to be glycosylated, which is present in a flexible linker. Interestingly, when Cys22 is mutated, sugar attachment is not required for sublancin antimicrobial activity. Furthermore, the sublancin-producing strain Bacillus subtilis 168 also becomes susceptible to such mutants. These data suggest that S-glycosylation may be important for self-resistance.

PMID: 21910430 [PubMed - indexed for MEDLINE]

Lichenicidin biosynthesis in Escherichia coli: licFGEHI immunity genes are not essential for lantibiotic production or self-protection.

Appl Environ Microbiol. 2011 Jul;77(14):5023-6

Authors: Caetano T, Krawczyk JM, Mösker E, Süssmuth RD, Mendo S

Abstract
This study demonstrated, for the first time, that immunity genes licFGEHI are not essential for self-protection and production of the two-component lantibiotic lichenicidin in the Gram-negative heterologous host Escherichia coli BLic5. Additionally, it was experimentally demonstrated that lichenicidin lantibiotics are active against the E. coli imp4213 strain, a mutant strain possessing a permeable outer membrane.

PMID: 21602391 [PubMed - indexed for MEDLINE]

Ruminococcin C, a new anti-Clostridium perfringens bacteriocin produced in the gut by the commensal bacterium Ruminococcus gnavus E1.

Biochimie. 2011 Sep;93(9):1487-94

Authors: Crost EH, Ajandouz EH, Villard C, Geraert PA, Puigserver A, Fons M

Abstract
When colonizing the digestive tract of mono-associated rats, Ruminococcus gnavus E1 - a bacterium isolated from human faeces - produced a trypsin-dependent anti-Clostridium perfringens substance collectively named Ruminococcin C (RumC). RumC was isolated from the caecal contents of E1-monocontaminated rats and found to consist of two antimicrobial fractions: a single peptide (RumCsp) of 4235 Da, and a mixture of two other peptides (RumCdp) with distinct molecular masses of 4324 Da and 4456 Da. Both RumCsp and RumCdp were as effective as metronidazole in combating C. perfringens and their activity spectra against different pathogens were established. Even if devoid of synergistic activity, the combination of RumCsp and RumCdp was observed to be much more resistant to acidic pH and high temperature than each fraction tested individually. N-terminal sequence analysis showed that the primary structures of these three peptides shared a high degree of homology, but were clearly distinct from previously reported amino acid sequences. Amino acid composition of the three RumC peptides did not highlight the presence of any Lanthionine residue. However, Edman degradation could not run beyond the 11th amino acid residue. Five genes encoding putative pre-RumC-like peptides were identified in the genome of strain E1, confirming that RumC was a bacteriocin. This is the first time that a bacteriocin produced in vivo by a human commensal bacterium was purified and characterized.

PMID: 21586310 [PubMed - indexed for MEDLINE]

Purification and characterization of a new Bacillus thuringiensis bacteriocin active against Listeria monocytogenes, Bacillus cereus and Agrobacterium tumefaciens.

Appl Biochem Biotechnol. 2011 Sep;165(1):300-14

Authors: Kamoun F, Fguira IB, Hassen NB, Mejdoub H, Lereclus D, Jaoua S

Abstract
This study reports on the identification, characterization and purification of a new bacteriocin, named Bacthuricin F103, from a Bacillus thuringiensis strain BUPM103. Bacthuricin F103 production began in the early exponential phase and reached a maximum in the middle of the same phase. Two chromatographic methods based on high performance liquid chromatography and fast protein liquid chromatography systems were used to purify Bacthuricin F103. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed that this bacteriocin had a molecular weight of approximately 11 kDa. It also showed a wide range of thermostability of up to 80 °C for 60 min and a broad spectrum of antimicrobial activity over a pH range of 3.0-10.0. This bacteriocin was noted, and for the first time, to exhibit potent antimicrobial activity against Agrobacterium subsp. strains, the major causal agents of crown gall disease in tomato and vineyard crops, and against several challenging organisms in food, such as Listeria monocytogenes and Bacillus cereus. Complete killing with immediate impact on cells was observed within a short period of time. The sequence obtained for Bacthuricin F103 by direct N-terminal sequencing shared considerable homology with hemolysin. Bacthuricin F103 was noted to act through the depletion of intracellular ions, which suggest that the cell membrane was a possible target to Bacthuricin F103.

PMID: 21487734 [PubMed - indexed for MEDLINE]