Mutagenesis of the Putative Catalytic Serine of LipN hydrolase from Mycobacterium ulcerans

Emily Pool Butler University
Faculty Sponsor(s): Geoff Hoops Butler University
LipN is a serine hydrolase from Mycobacterium ulcerans, which causes Buruli ulcer, a soft-tissue disease. While little is known about LipN’s physiological function, it may be involved in xenobiotic degradation, and the LipN ortholog in Mycobacterium tuberculosis has shown catalytic activity while M. tuberculosis is dormant. Previously, the proposed catalytic serine was mutated to an alanine, and the protein retained significant activity. We mutated the putative catalytic serine into threonine, aspartic acid, and glutamic acid to observe any effects on catalysis. Catalytic activity was measured using fluorogenic ester assays. The S to T mutant had a small effect on the wild-type protein, indicating that the orientation of the nucleophile was either hindered or beneficially oriented by the addition of the methyl group. Proteomic analysis indicated that the catalytic serine in LipN of M. tuberculosis is phosphorylated, so the S to D/E mutants were designed to explore the possibility that the wild-type LipN was phosphorylated via post-translational modification in vivo. Together, we provided mechanistic, structural, and regulatory information about this mycobacterial enzyme.
Biochemistry & Molecular Biology
Oral Presentation

When & Where

11:00 AM
Gallahue Hall 108