Showing 1 - 3 of 3 Items

Date: 2020-12-11

Creator: Karen D. Moulton, Adedunmola P. Adewale, Hallie A. Carol, Sage A. Mikami, Danielle H., Dube

Access: Open access

Bacterial cell surface glycans are quintessential drug targets due to their critical role in colonization of the host, pathogen survival, and immune evasion. The dense cell envelope glycocalyx contains distinctive monosaccharides that are stitched together into higher order glycans to yield exclusively bacterial structures that are critical for strain fitness and pathogenesis. However, the systematic study and inhibition of bacterial glycosylation enzymes remains challenging. Bacteria produce glycans containing rare sugars refractory to traditional glycan analysis, complicating the study of bacterial glycans and the identification of their biosynthesis machinery. To ease the study of bacterial glycans in the absence of detailed structural information, we used metabolic glycan labeling to detect changes in glycan biosynthesis. Here, we screened wild-type versus mutant strains of the gastric pathogen Helicobacter pylori, ultimately permitting the identification of genes involved in glycoprotein and lipopolysaccharide biosynthesis. Our findings provide the first evidence that H. pylori protein glycosylation proceeds via a lipid carrier-mediated pathway that overlaps with lipopolysaccharide biosynthesis. Protein glycosylation mutants displayed fitness defects consistent with those induced by small molecule glycosylation inhibitors. Broadly, our results suggest a facile approach to screen for bacterial glycosylation genes and gain insight into their biosynthesis and functional importance, even in the absence of glycan structural information.

Date: 2021-01-01

Creator: Andrew Close Bolender

Access: Open access

Plant cell adhesion is mediated by the extracellular matrix (ECM) or cell wall and plays an important role in plant morphogenesis and development. The amount, modification, and cleavage of pectin in the cell wall are major contributors to the adhesive properties of the ECM. To gain a more complete picture of plant cell adhesion processes, Arabidopsis thaliana seedlings were previously mutagenized and screened for hypocotyl adhesion defects. Genomic sequencing of one plant exhibiting an adhesion defect, isolate 242, showed that two mutations, one in cellulose synthase (CesA1) and another in a sugar transporter, are candidates for the causative mutation. This thesis reports that CesA1 is necessary for proper plant cell adhesion, while the sugar transporter encoded at At4g32390 is not. Dark grown seedlings homozygous for mutations in CesA1 stain in ruthenium red, indicating atypical adhesion, while those homozygous for null mutations in At4g32390 do not. Previous study of another adhesion mutant revealed ELMO1, a Golgi protein necessary for plant cell adhesion, and four additional homologs ELMO2-5 in the A. thaliana genome. Two of these homologs, ELMO2 and ELMO3, fused to GFP, colocalized with mCherry-MEM1 markers in the Golgi, but not mCherry-NLM12 ER markers, indicating that ELMO2 and ELMO3 are also Golgi proteins.

Date: 2024-01-01

Creator: William Joseph Surks

Access: Access restricted to the Bowdoin Community