Remodeling of O Antigen in Mucoid Pseudomonas aeruginosa via Transcriptional Repression of wzz2

• Type of Material: Article
• Authors: Ashley R. Cross, Emory University; Joanna B. Goldberg, Emory University; E. Peter Greenberg, University of Washington
• Language: English
• Date: 2019-01-01
• Publisher: American Society for Microbiology: Open Access Journals
• Publication Version: Final Published Version
• Copyright Statement: © 2019 Cross and Goldberg.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1128/mBio.02914-18
• Title of Journal or Parent Work: mBio
• ISSN: 2150-7511
• Volume: 10
• Issue: 1
• Start Page: e02914
• End Page: 18
• Grant/Funding Information: Additional funding was awarded by the NIH and the CFF to J.B.G. under award numbers R21AI122192 and GOLDBE16G0, respectively.; The National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health (NIH) under award number F31AI136310 also supported A.R.C.; This work was partially supported by a predoctoral fellowship to A.R.C. from the Cystic Fibrosis Foundation (CFF)-funded CF@LANTA RDP Center (MCCART15R0), CF-AIR, components of the Emory+Children’s CF Center of Excellence at Emory University, and Children’s Healthcare of Atlanta.
• Keywords: CHAIN-LENGTH; CYSTIC-FIBROSIS; EXPRESSION; ALGINATE PRODUCTION; Science & Technology; lipopolysaccharide; NTRC FAMILY; DNA-BINDING PROTEIN; alginate; FLAGELLUM BIOSYNTHESIS; Microbiology; TRANSPOSON MUTANT LIBRARY; Pseudomonas aeruginosa; SIGMA-FACTOR; RESPONSE REGULATOR; Life Sciences & Biomedicine
• Research Categories: Health Sciences, Pathology; Biology, Genetics

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic lung infections in people with cystic fibrosis (CF). Chronic P. aeruginosa isolates generally do not express O antigen and often have a mucoid phenotype, which is characterized by the overproduction of the exopolysaccharide alginate. Therefore, O antigen expression and the mucoid phenotype may be coordinately regulated upon chronic adaption to the CF lung. Here we demonstrate that PDO300, a mucoid strain derived from the nonmucoid laboratory isolate PAO1, does not produce very long O antigen due to decreased expression of Wzz2, the very long O antigen chain length control protein, and that mucoid clinical isolates express reduced levels of Wzz2 compared to nonmucoid isolates. Further, we show that forcing the expression of very long O antigen by PDO300, by providing wzz2 in trans, does not alter alginate production, suggesting that sugar precursors are not limited between the two biosynthesis pathways. Moreover, we confirm that AmrZ, a transcription factor highly expressed in mucoid strains, is a negative regulator of wzz2 promoter activity and very long O antigen expression. These experiments identify the first transcriptional regulator of O antigen chain length in P. aeruginosa and support a model where transition to a chronic mucoid phenotype is correlated with downregulation of very long O antigen through decreased Wzz2 production. IMPORTANCE Detection of mucoid Pseudomonas aeruginosa, characterized by the overproduction of alginate, is correlated with the establishment of a chronic pulmonary infection and disease progression in people with cystic fibrosis (CF). In addition to the overproduction of alginate, loss of O antigen lipopolysaccharide production is also selected for in chronic infection isolates. In this study, we have identified the regulatory network that inversely regulates O antigen and alginate production. Understanding the regulation of these chronic phenotypes will elucidate mechanisms that are important for the establishment of a long-term P. aeruginosa lung infection and ultimately provide an opportunity for intervention. Preventing P. aeruginosa from chronically adapting to the CF lung environment could provide a better outcome for people who are infected.