title: Expression of mucoid induction factor MucE is dependent upon the alternate sigma factor AlgU in Pseudomonas aeruginosa.
abstract: BACKGROUND
  Alginate overproduction in P. aeruginosa, also referred to as mucoidy, is a poor prognostic marker for patients with cystic fibrosis (CF). We previously reported the construction of a unique mucoid strain which overexpresses a small envelope protein MucE leading to activation of the protease AlgW. AlgW then degrades the anti-sigma factor MucA thus releasing the alternative sigma factor AlgU/T (σ(22)) to initiate transcription of the alginate biosynthetic operon.
  
  
  RESULTS
  In the current study, we mapped the mucE transcriptional start site, and determined that P(mucE) activity was dependent on AlgU. Additionally, the presence of triclosan and sodium dodecyl sulfate was shown to cause an increase in P(mucE) activity. It was observed that mucE-mediated mucoidy in CF isolates was dependent on both the size of MucA and the genotype of algU. We also performed shotgun proteomic analysis with cell lysates from the strains PAO1, VE2 (PAO1 with constitutive expression of mucE) and VE2ΔalgU (VE2 with in-frame deletion of algU). As a result, we identified nine algU-dependent and two algU-independent proteins that were affected by overexpression of MucE.
  
  
  CONCLUSIONS
  Our data indicates there is a positive feedback regulation between MucE and AlgU. Furthermore, it seems likely that MucE may be part of the signal transduction system that senses certain types of cell wall stress to P. aeruginosa.
authors.forename: Yeshi
authors.initials: Y
authors.lastname: Yin
authors.forename: F Heath
authors.initials: FH
authors.lastname: Damron
authors.forename: T Ryan
authors.initials: TR
authors.lastname: Withers
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Pritchett
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Schurr
authors.affiliation: Department of Biochemistry and Microbiology, Joan C, Edwards School of Medicine at Marshall University, Huntington, WV 25755, USA. yuh@marshall.edu.
authors.forename: Hongwei D
authors.initials: HD
authors.lastname: Yu
mesh_terms: D000464:Alginates; D001426:Bacterial Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D020723:Glucuronic Acid / Q000096:biosynthesis; D006603:Hexuronic Acids; D010447:Peptide Hydrolases / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics*; D012808:Sigma Factor / Q000378:metabolism*; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: C079619:AlgU protein, Pseudomonas aeruginosa; D000464:Alginates; D001426:Bacterial Proteins; D006603:Hexuronic Acids; D012808:Sigma Factor; D020723:Glucuronic Acid; D010447:Peptide Hydrolases