Date of Award


Document Type


Degree Name

Master of Science (M.S.)


Biological Sciences

First Advisor

Douglas Risser

First Committee Member

Douglas Weiser

Second Committee Member

Craig Vierra


Type IV pili (T4P) systems are widely utilized among bacteria to power and direct surface motility. The production and secretion of a viscous polysaccharide to provide friction and resistance to the extended pilus structure is seen in several species of cyanobacteria including Nostoc punctiforme. The complex coregulation of polysaccharide secretion and T4P motor activity is not fully understood, although studies indicate a consistent relationship between functional motility and intact pathways of polysaccharide secretion and pilus extension in cyanobacteria. Using a combination of protein-protein interaction analysis, cytological studies, and comparative genomics this study proposes a theoretical mechanism for T4P motor influenced regulation of hormogonium polysaccharide secretion by a heat-shock protein (HSP) DnaK-type chaperone system in N. punctiforme. The results of this study indicate a tripartite HSP system consisting of DnaK1, DnaJ3, and coregulator GrpE is influenced by the activation of certain motor proteins in the T4P complex and are required for the production and secretion of hormogonium polysaccharide. Conservation of this system in Synechocystis sp. also implies a potential system that is conserved among all motile cyanobacteria for regulation of T4P.



Included in

Biology Commons



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