Katzif Samuel, Danavall Damien, Bowers Samera, Balthazar Jacqueline T, Shafer William M
Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Infect Immun. 2003 Aug;71(8):4304-12. doi: 10.1128/IAI.71.8.4304-4312.2003.
A Tn551 insertional library of Staphylococcus aureus strain ISP479 was challenged with an antimicrobial peptide (CG 117-136) derived from human neutrophil cathepsin G (CG). After repeated selection and screening of surviving colonies, a mutant was identified that expressed increased resistance to CG 117-136. Southern hybridization analysis revealed that the Tn551 insert in this mutant (SK1) was carried on a 10.6-kb EcoRI chromosomal DNA fragment. Subsequent physical mapping of this Tn551 insert revealed that it was positioned between a putative promoter sequence and the translational start codon of the cspA gene, which encodes a protein (CspA) highly similar to the major cold shock proteins CspA and CspB of Escherichia coli and Bacillus subtilis, respectively. This Tn551 insertion as well as a separate deletion-insertion mutation in cspA decreased the capacity of S. aureus to respond to the stress of cold shock and increased resistance to CG 117-136. The results indicate for the first time that a physiologic link exists between bacterial susceptibility to an antimicrobial peptide and a stress response system.
用源自人中性粒细胞组织蛋白酶G（CG）的抗菌肽（CG 117 - 136）对金黄色葡萄球菌菌株ISP479的Tn551插入文库进行挑战。在对存活菌落进行反复筛选后，鉴定出一个对CG 117 - 136表现出增强抗性的突变体。Southern杂交分析表明，该突变体（SK1）中的Tn551插入位于一个10.6 kb的EcoRI染色体DNA片段上。随后对该Tn551插入片段进行物理图谱分析，发现它位于假定的启动子序列和cspA基因的翻译起始密码子之间，该基因编码一种与大肠杆菌和枯草芽孢杆菌的主要冷休克蛋白CspA和CspB高度相似的蛋白质（CspA）。这种Tn551插入以及cspA中一个单独的缺失 - 插入突变降低了金黄色葡萄球菌对冷休克应激的反应能力，并增加了对CG 117 - 136的抗性。结果首次表明，细菌对抗菌肽的敏感性与应激反应系统之间存在生理联系。
