Alexander M. Justen

Degree Program: Integrated Program in Biochemistry
Faculty Advisor: Laura L. Kiessling
Phone: (608) 262-3040

Current Research

Carbohydrate polymers play vital roles in cell biology, however, despite their importance, little is known about enzymatic control of glycan length. The mycobacterial cell wall galactan is an essential carbohydrate polymer conserved across mycobacteria, including the pathogen M. tuberculosis (M. tb). The galactan is composed of monosaccharides of D-galactofuranose (Galf). My research focuses on employing assembly of the mycobacterial cell wall galactan as a model of polysaccharide length control. In specific, my research seeks to answer the following questions: (1) Can galactan length be manipulated genetically? All species within the suborder Corynebacterineae produce a structural polysaccharide termed the galactan. Past research in our laboratory has shown the glycosyltransferase responsible for galactan polymerization, GlfT2, is endowed with intrinsic length control ability. My research focuses on alteration of GlfT2 both in vitro and in vivo in order to manipulate galactan length. (2) How does galactan length influence mycobacterial physiology? The galactan is an essential structural glycopolymer in mycobacteria. It effectively serves as a covalent linker between two portions of the cell wall. Despite the fact that all known linkages required to complete cell wall assembly occur within the first 12 residues, the galactan is usually 30 Galf units in length. Thus, the importance behind galactan length remains unclear. Here, I seek to understand the biological consequences of galactan length truncation.


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