Loss of IrpT function in Lactococcus lactis subsp. lactis N8 results in increased nisin resistance.
The antibiotic nisin, produced by Lactococcus lactis subsp. lactis N8, offers an extensive commercial prospect as natural food preservatives. The nisin immunity of the L. lactis strains is regulated by a variety of mechanisms. In this study, we isolated a L. lactis L31 strain with increased nisin resistance from a mini-Mu transposon mutant pool of strain N8. The single Mu insertion in strain L31 was in the irpT gene with unknown function. By comparing the proteomic profiles of L. lactis L31 and its parental strain, we found that changes occurred in the synthesis of a protein involved in cell wall biosynthesis (RmlD). Strain L31 had 13.7% higher content of rhamnose in the cell wall than the N8 strain. Overexpression of RmlD involved in the synthesis of dTDP-L: -rhamnose in the nisin-sensitive MG1363 strain increased nisin resistance of the strain. The results indicate that these cellular proteins effected nisin resistance in L. lactis N8.
Xuanyuan
Zhengzheng
Z
College of Life Sciences, Nankai University, Tianjin, China. xuanyuanzheng@yahoo.com.cn
Wu
Zhenzhou
Z
Li
Ruiqing
R
Jiang
Dezhou
D
Su
Junjie
J
Xu
Haijin
H
Bai
Yanling
Y
Zhang
Xiuming
X
Saris
Per Erik Joakim
PE
Qiao
Mingqiang
M
D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015139:Blotting, Southern; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D015870:Gene Expression; D005798:Genes, Bacterial; D013294:Lactococcus lactis / Q000187:drug effects* / Q000235:genetics*; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009561:Nisin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C094909:NisI protein, Lactococcus lactis; C094910:NisT protein, Lactococcus lactis; D009561:Nisin