GFP plasmid-induced defects in Salmonella invasion depend on plasmid architecture, not protein expression

• DOI: 10.1099/mic.0.025700-0
• Publication Date: 2009-02-07T08:31:54Z
• Authors: Leann Clark; Isabel Martinez-A...; Tom J. Humphrey; Mark A. Jepson
• Keywords: Salmonella typhimurium; 0301 basic medicine; 570; Virulence; Green Fluorescent Proteins; Gene Expression; 630; Cell Line; Culture Media; 03 medical and health sciences; Dogs; Salmonella Infections; Animals; Humans; Plasmids

We have investigated the impact of plasmids and GFP expression on invasion cultured epithelial cells by Salmonella enterica Typhimurium strain SL1344. The invasiveness SL1344 carrying derived from pBR322, encoding promoterless or constitutively expressed rpsM -GFP, was compared under optimal growth conditions with that SL1344(pBR322), unmodified a chromosome-integrated -GFP. pBR322 exhibited normal invasion, but presence modified impaired invasiveness, impairment exacerbated plasmid-encoded chloramphenicol resistance (Cm R ). Using different antibiotic marker, kanamycin (Km ), did not impair invasiveness. Despite effect Cm , containing chromosomally encoded GFP, also gene, as invasive wild-type. To investigate mechanism which plasmid carriage decreases we monitored SPI-1 gene using prgH promoter activity an index activity. An : gfp reporter construct lower during exponential phase when incorporating mirroring data. These data provide evidence suppression is major factor in loss associated carriage. Our findings indicate some plasmids, especially those should be used caution, virulence traits may affected their presence. Integration proteins into bacterial chromosome, however, appears to circumvent adverse effects observed plasmids.