RESUMO
Curli amyloid fibers are the major protein component of the extracellular matrix produced by Enterobacteriaceae during biofilm formation. Curli are required for proper biofilm development and environmental persistence by Escherichia coli. Here, we present a complete and vetted genetic analysis of functional amyloid fiber biogenesis. The Keio collection of single gene deletions was screened on Congo red indicator plates to identify E. coli mutants that had defective amyloid production. We discovered that more than three hundred gene products modulated curli production. These genes were involved in fundamental cellular processes such as regulation, environmental sensing, respiration, metabolism, cell envelope biogenesis, transport, and protein turnover. The alternative sigma factors, σS and σE, had opposing roles in curli production. Mutations that induced the σE or Cpx stress response systems had reduced curli production, while mutant strains with increased σS levels had increased curli production. Mutations in metabolic pathways, including gluconeogenesis and the biosynthesis of lipopolysaccharide (LPS), produced less curli. Regulation of the master biofilm regulator, CsgD, was diverse, and the screen revealed several proteins and small RNAs (sRNA) that regulate csgD messenger RNA (mRNA) levels. Using previously published studies, we found minimal overlap between the genes affecting curli biogenesis and genes known to impact swimming or swarming motility, underlying the distinction between motile and sessile lifestyles. Collectively, the diversity and number of elements required suggest curli production is part of a highly regulated and complex developmental pathway in E. coli.
Assuntos
Amiloide/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Fator sigma/genética , Transativadores/genética , Amiloide/biossíntese , Biofilmes/crescimento & desenvolvimento , Matriz Extracelular/genética , Regulação Bacteriana da Expressão Gênica , Gluconeogênese/genética , Lipopolissacarídeos/biossíntese , Lipopolissacarídeos/genética , Mutação , Regiões Promotoras Genéticas , RNA Mensageiro/genéticaRESUMO
BACKGROUND: Minimally invasive techniques have been developed to treat migraine headache, and several reports have shown efficacy in treating select patients who are refractory to conventional therapies. Although there is a growing body of evidence supporting migraine surgery, no study has examined its adoption by plastic surgeons in the United States. METHODS: A Web-based survey consisting of 17 ad hoc questions was designed to ascertain respondents' demographics, experience, knowledge, and attitudes regarding migraine surgery. After pilot testing, the survey was distributed by means of email to the entire membership of the American Society of Plastic Surgeons. RESULTS: A total of 3747 American Society of Plastic Surgeons members were surveyed, and 193 surveys were completed, for a response rate of 5.2 percent. Thirty-four respondents (18 percent) had performed surgery to treat migraine headache. Among those who have performed migraine surgery, over 80 percent reported improvement in patient symptoms. Of those who have not performed migraine surgery, 60 percent would be interested if an appropriate patient was referred to them by a neurologist. CONCLUSION: Although there is interest in migraine surgery among a subset of plastic surgeons, significant barriers to performing migraine surgery include deficient referral patterns from neurologists and lack of familiarity with the concept and techniques of migraine surgery.