Zinc affects siderophore-mediated high affinity iron uptake systems in the rhizosphere Pseudomonas aeruginosa 7NSK2.
Zinc concentrations ranging between 0.1 and 1 mM only slightly reduced maximal growth of wild-type Pseudomonas aeruginosa 7NSK2 in iron-limiting casamino acid medium, but had a clear negative effect on the growth of mutant MPFM1 (pyoverdin negative) and especially mutant KMPCH (pyoverdin and pyochelin negative). Production of pyoverdin by wild-type strain 7NSK2 was significantly increased in the presence of 0.5 mM zinc and could not be repressed by iron even at a concentration of 100 microM. Siderophore detection via isoelectrofocusing revealed that mutant KMPCH did not produce any siderophores, while mutant MPFM1 overproduced a siderophore with an acidic isoelectric point, most likely pyochelin. Pyochelin production by MPFM1 was stimulated by the presence of zinc in a similar way as pyoverdin for the wild-type. Analysis of outer membrane proteins revealed that three iron regulated outer membrane proteins (IROMPs) (90, 85 and 75 kDa) were induced by iron deficiency in the wild-type, while mutants were found to have altered IROMP profiles. Zinc specifically enhanced the production of a 85 kDa IROMP in 7NSK2, a 75 kDa IROMP in MPFM1 and a 90 kDa IROMP in KMPCH.
Höfte
M
M
Laboratorium voor Fytopathologie & Fytovirologie, Universiteit Gent, Belgium.
Buysens
S
S
Koedam
N
N
Cornelis
P
P
D001425:Bacterial Outer Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D007501:Iron / Q000378:metabolism*; D007525:Isoelectric Focusing; D007700:Kinetics; D016296:Mutagenesis; D009842:Oligopeptides; D010636:Phenols / Q000302:isolation & purification / Q000378:metabolism*; D010860:Pigments, Biological / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D017262:Siderophores / Q000302:isolation & purification / Q000378:metabolism*; D013844:Thiazoles; D015032:Zinc / Q000494:pharmacology*
D001425:Bacterial Outer Membrane Proteins; D009842:Oligopeptides; D010636:Phenols; D010860:Pigments, Biological; D017262:Siderophores; D013844:Thiazoles; C025316:pyochelin; C042453:pyoverdin; D007501:Iron; D015032:Zinc