A complex multilevel attack on Pseudomonas aeruginosa algT/U expression and algT/U activity results in the loss of alginate production
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A complex multilevel attack on Pseudomonas aeruginosa algT/U expression and algT/U activity results in the loss of alginate production. / Sautter, Robert; Ramos, Damaris; Schneper, Lisa; Ciofu, Oana; Wassermann, Tina; Koh, Chong-Lek; Heydorn, Arne; Hentzer, Morton; Høiby, Niels; Kharazmi, Arsalan; Molin, Søren; Devries, Caroline A; Ohman, Dennis E; Mathee, Kalai.
In: Gene, Vol. 498, No. 2, 01.05.2012, p. 242-253.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - A complex multilevel attack on Pseudomonas aeruginosa algT/U expression and algT/U activity results in the loss of alginate production
AU - Sautter, Robert
AU - Ramos, Damaris
AU - Schneper, Lisa
AU - Ciofu, Oana
AU - Wassermann, Tina
AU - Koh, Chong-Lek
AU - Heydorn, Arne
AU - Hentzer, Morton
AU - Høiby, Niels
AU - Kharazmi, Arsalan
AU - Molin, Søren
AU - Devries, Caroline A
AU - Ohman, Dennis E
AU - Mathee, Kalai
N1 - Copyright © 2011. Published by Elsevier B.V.
PY - 2012/5/1
Y1 - 2012/5/1
N2 - Infection by the opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality seen in cystic fibrosis (CF) patients. This is mainly due to the genotypic and phenotypic changes of the bacteria that cause conversion from a typical nonmucoid to a mucoid form in the CF lung. Mucoid conversion is indicative of overproduction of a capsule-like polysaccharide called alginate. The alginate-overproducing (Alg(+)) mucoid phenotype seen in the CF isolates is extremely unstable. Low oxygen tension growth of mucoid variants readily selects for nonmucoid variants. The switching off mechanism has been mapped to the algT/U locus, and the molecular basis for this conversion was partially attributed to mutations in the algT/U gene itself. To further characterize molecular changes resulting in the unstable phenotype, an isogenic PAO1 derivative that is constitutively Alg(+) due to the replacement of the mucA with mucA22 (PDO300) was used. The mucA22 allele is common in mucoid CF isolates. Thirty-four spontaneous nonmucoid variants, or sap (suppressor of alginate production) mutants, of PDO300 were isolated under low oxygen tension. About 40% of the sap mutants were rescued by a plasmid carrying algT/U (Group A). The remaining sap mutants were not (Group B). The members of Group B fall into two subsets: one similar to PAO1, and another comparable to PDO300. Sequence analysis of the algT/U and mucA genes in Group A shows that mucA22 is intact, whereas algT/U contains mutations. Genetic complementation and sequencing of one Group B sap mutant, sap22, revealed that the nonmucoid phenotype was due to the presence of a mutation in PA3257. PA3257 encodes a putative periplasmic protease. Mutation of PA3257 resulted in decreased algT/U expression. Thus, inhibition of algT/U is a primary mechanism for alginate synthesis suppression.
AB - Infection by the opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality seen in cystic fibrosis (CF) patients. This is mainly due to the genotypic and phenotypic changes of the bacteria that cause conversion from a typical nonmucoid to a mucoid form in the CF lung. Mucoid conversion is indicative of overproduction of a capsule-like polysaccharide called alginate. The alginate-overproducing (Alg(+)) mucoid phenotype seen in the CF isolates is extremely unstable. Low oxygen tension growth of mucoid variants readily selects for nonmucoid variants. The switching off mechanism has been mapped to the algT/U locus, and the molecular basis for this conversion was partially attributed to mutations in the algT/U gene itself. To further characterize molecular changes resulting in the unstable phenotype, an isogenic PAO1 derivative that is constitutively Alg(+) due to the replacement of the mucA with mucA22 (PDO300) was used. The mucA22 allele is common in mucoid CF isolates. Thirty-four spontaneous nonmucoid variants, or sap (suppressor of alginate production) mutants, of PDO300 were isolated under low oxygen tension. About 40% of the sap mutants were rescued by a plasmid carrying algT/U (Group A). The remaining sap mutants were not (Group B). The members of Group B fall into two subsets: one similar to PAO1, and another comparable to PDO300. Sequence analysis of the algT/U and mucA genes in Group A shows that mucA22 is intact, whereas algT/U contains mutations. Genetic complementation and sequencing of one Group B sap mutant, sap22, revealed that the nonmucoid phenotype was due to the presence of a mutation in PA3257. PA3257 encodes a putative periplasmic protease. Mutation of PA3257 resulted in decreased algT/U expression. Thus, inhibition of algT/U is a primary mechanism for alginate synthesis suppression.
KW - Alginates
KW - Amino Acid Sequence
KW - Bacterial Outer Membrane Proteins
KW - Bacterial Proteins
KW - Base Sequence
KW - DNA Transposable Elements
KW - Gene Expression Regulation, Bacterial
KW - Genetic Complementation Test
KW - Glucuronic Acid
KW - Hexuronic Acids
KW - Microbial Sensitivity Tests
KW - Molecular Sequence Data
KW - Mutation
KW - Peptide Hydrolases
KW - Pseudomonas aeruginosa
KW - Sigma Factor
KW - beta-Lactamases
U2 - 10.1016/j.gene.2011.11.005
DO - 10.1016/j.gene.2011.11.005
M3 - Journal article
C2 - 22088575
VL - 498
SP - 242
EP - 253
JO - Gene
JF - Gene
SN - 0378-1119
IS - 2
ER -
ID: 49281039