title: Serum albumin alters the expression of iron-controlled genes in Pseudomonas aeruginosa.
abstract: Pseudomonas aeruginosa, which causes serious infections in immunocompromised patients, produces numerous virulence factors, including exotoxin A and the siderophore pyoverdine. As production of these virulence factors is influenced by the host environment, we examined the effect serum has on global transcription within P. aeruginosa strain PAO1 at different phases of growth in an iron-deficient medium. At early exponential phase, serum significantly enhanced expression of 138 genes, most of which are repressed by iron, including pvdS, regA and the pyoverdine synthesis genes. However, serum did not interfere with the repression of these genes by iron. Serum enhanced regA expression in a fur mutant of PAO1 but not in a pvdS mutant. The serum iron-binding protein apotransferrin, but not ferritin, enhanced regA and pvdS expression. However, in PAO1 grown in a chemically defined medium that contains no iron, serum but not apotransferrin enhanced pvdS and regA expression. While complement inactivation failed to eliminate this effect, albumin absorption reduced the effect of serum on pvdS and regA expression in the iron-deficient medium chelexed tryptic soy broth dialysate. Additionally, albumin absorption eliminated the effect of serum on pvdS and regA expression in the chemically defined medium. These results suggest that serum enhances the expression of P. aeruginosa iron-controlled genes by two mechanisms: one through apotransferrin and another one through albumin.
authors: Department of Microbiology & Immunology, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors: Cassandra
authors: C
authors: Kruczek
authors: Department of Pathology, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors: Mitchell
authors: M
authors: Wachtel
authors: Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors: Magdy S
authors: MS
authors: Alabady
authors: United States Department of Agriculture, Cropping Systems Research Laboratory, The Plant Stress and Germplasm Development Unit, Lubbock, TX 79415, USA.
authors: Paxton R
authors: PR
authors: Payton
authors: Department of Microbiology & Immunology, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors: Jane A
authors: JA
authors: Colmer-Hamood
authors: Department of Microbiology & Immunology, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors: Abdul N
authors: AN
authors: Hamood
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007501:Iron / Q000378:metabolism*; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012709:Serum Albumin; D007501:Iron