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dc.contributor.authorMoradali, M Fata
dc.contributor.authorGhods, Shirin
dc.contributor.authorRehm, Bernd HA
dc.date.accessioned2017-07-31T05:16:18Z
dc.date.available2017-07-31T05:16:18Z
dc.date.issued2017
dc.identifier.issn0099-2240
dc.identifier.doi10.1128/AEM.03499-16
dc.identifier.urihttp://hdl.handle.net/10072/342846
dc.description.abstractThe exopolysaccharide alginate, produced by the opportunistic human pathogen Pseudomonas aeruginosa, confers a survival advantage to the bacterium by contributing to the formation of characteristic biofilms during infection. Membrane-anchored proteins Alg8 (catalytic subunit) and Alg44 (copolymerase) constitute the alginate polymerase that is being activated by the second messenger molecule bis-(3′, 5′)-cyclic dimeric GMP (c-di-GMP), but the mechanism of activation remains elusive. To shed light on the c-di-GMP-mediated activation of alginate polymerization in vivo, an in silico structural model of Alg8 fused to the c-di-GMP binding PilZ domain informed by the structure of cellulose synthase, BcsA, was developed. This structural model was probed by site-specific mutagenesis and different cellular levels of c-di-GMP. Results suggested that c-di-GMP-mediated activation of alginate polymerization involves amino acids residing at two loops, including H323 (loop A) and T457 and E460 (loop B), surrounding the catalytic site in the predicted model. The activities of the respective Alg8 variants suggested that c-di-GMP-mediated control of substrate access to the catalytic site of Alg8 is dissimilar to the known activation mechanism of BcsA. Alg8 variants responded differently to various c-di-GMP levels, while MucR imparted c-di-GMP for activation of alginate polymerase. Furthermore, we showed that Alg44 copolymerase constituted a stable dimer, with its periplasmic domains required for protein localization and alginate polymerization and modification. Superfolder green fluorescent protein (GFP) fusions of Alg8 and Alg44 showed a nonuniform, punctate, and patchy arrangement of both proteins surrounding the cell. Overall, this study provides insights into the c-di-GMP-mediated activation of alginate polymerization while assigning functional roles to Alg8 and Alg44, including their subcellular localization and distribution.
dc.description.peerreviewedYes
dc.languageEnglish
dc.language.isoeng
dc.publisherAmerican Society for Microbiology
dc.relation.ispartofpagefrome03499-16-1
dc.relation.ispartofpagetoe03499-16-20
dc.relation.ispartofissue9
dc.relation.ispartofjournalApplied and Environmental Microbiology
dc.relation.ispartofvolume83
dc.subject.fieldofresearchMicrobiology not elsewhere classified
dc.subject.fieldofresearchcode060599
dc.titleActivation mechanism and cellular localization of membrane-anchored alginate polymerase in Pseudomonas aeruginosa
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
dc.description.versionVersion of Record (VoR)
gro.rights.copyright© 2017 American Society for Microbiology. The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
gro.hasfulltextFull Text
gro.griffith.authorRehm, Bernd


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