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All it takes to express virulence genes (361.3)
Author(s) -
Artsimovitch Irina,
Liu Zhaokun,
NandyMazumdar Monali,
Tomar Sushil
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.361.3
Subject(s) - operon , biology , gene , rna polymerase , transcription (linguistics) , genetics , ribosome , plasmid , microbiology and biotechnology , rna , escherichia coli , linguistics , philosophy
Horizontal gene transfer shapes bacterial evolution, enabling adaptation to new environments, efficient pathogenesis, and acquisition of antibiotic resistance. However, expression of foreign DNA may have detrimental, and even lethal, cellular effects, and is thus tightly regulated. In Escherichia coli, NusG and its specialized paralog RfaH play opposite roles in expression of horizontally‐transferred genes: NusG cooperates with a termination factor Rho to silence transcription of foreign DNA, whereas RfaH activates several long laterally acquired operons that encode cell wall and capsule biosynthesis machineries as well as secreted toxins. RfaH‐dependent operons lack Shine‐Dalgarno elements and have many rare codons, suggesting that they are translated inefficiently. Consistently, Rho decreases expression of a model rfb operon >700 fold. RfaH, when present, eliminates Rho‐mediated polarity by three mechanisms. First, RfaH decreases RNA polymerase pausing, making it resistant to Rho. Second, RfaH excludes NusG from the transcription elongation complex, thereby inhibiting Rho‐mediating RNA release. Third, RfaH directly interacts with the ribosomal protein S10 and appears to recruit the 30S subunit to mRNA instead of a Shine‐Dalgarno element. Together, these three mechanisms ensure robust expression of RfaH‐dependent genes required for virulence in some enterobacterial pathogens. RfaH paralogs are also present on large conjugative plasmids, suggesting their broad role in activation of horizontally‐transferred genes.