Carrageenan desulfation and depolymerization by the marine isolate Pseudoalteromonas sp. PS47

Simple item page
dc.contributor.authorHettle, John Andrew
dc.contributor.supervisorBoraston, Alisdair Bennett
dc.date.accessioned2018-12-24T19:07:10Z
dc.date.copyright2018en_US
dc.date.issued2018-12-24
dc.degree.departmentDepartment of Biochemistry and Microbiologyen_US
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractCarrageenans are sulfated polysaccharides found in the cell walls of red algae with 20 – 30 % of the dry weight coming from sulfate esters. The understanding of how heterotrophic bacteria desulfate and depolymerize carrageenan has become a rather arduous endeavor as there are 15 different classes of carrageenan distinguished by the degree of sulfation and the presence or absence of a unique galactose derivative, the 3,6-anhydro-D-galactose. The depolymerization of carrageenan requires the removal of the sulfate substituents, a role fulfilled by sulfatases, which hydrolyze sulfate esters playing a key role in the regulation of sulfation states that determine the function of sulfated biomolecules. Through structural, mechanistic, and sequence-based studies a highly conserved sulfate-binding motif has been identified among sulfatases; however, the molecular determinants for substrate specificity remain largely speculative. Additionally, the largest sulfatase family S1, requires a unique catalytic residue resulting from a post-translationally modified cysteine in order to be functional thus making them difficult to study in vitro. Using a strain of Pseudoalteromonas sp. PS47 isolated in the Boraston Lab I show that the depolymerization of carrageenan is dependent on the degree of sulfation and that recognition of the leaving group is the driving force behind S1 specificity. With little information on the recognition of sulfated biomolecules, the X-ray crystal structures of the three sulfatases from PS47; PsS1_19A, PsS1_19B, and PsS1_NC in complex with their biological substrates provides a deeper understanding of how carbohydrate specific sulfatases recognize their cognate substrate and how this recognition of the leaving group can be extended to other S1 sulfatase families. Furthermore, I show that an exo-acting glycoside hydrolase (PsGH42) requires desulfation of carrageenan oligosaccharides before it can hydrolyze the β-glycosidic linkage, a new specificity of family 42. This research demonstrates how carrageenan depolymerization is entirely dependent on the functionality and specificity of the sulfatases found within the carrageenan utilization locus.en_US
dc.description.embargo2019-12-07
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/10458
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectSulfataseen_US
dc.subjectX-ray crystallographyen_US
dc.subjectCarrageenanen_US
dc.subjectSulfatase active site subsite nomenclatureen_US
dc.titleCarrageenan desulfation and depolymerization by the marine isolate Pseudoalteromonas sp. PS47en_US
dc.typeThesisen_US

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Hettle_JohnAndrew_PhD_2018.pdf
Size:
163.69 MB
Format:
Adobe Portable Document Format
Description:
Main article
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download

Collections

Electronic Theses and Dissertations (ETD)
Theses (Biochemistry and Microbiology)
 
University of Victoria Libraries

We acknowledge and respect the Lək̓ʷəŋən (Songhees and Esquimalt) Peoples on whose territory the university stands, and the Lək̓ʷəŋən and W̱SÁNEĆ Peoples whose historical relationships with the land continue to this day.