Date Approved

9-22-2025

Embargo Period

9-22-2025

Document Type

Thesis

Degree Name

M.S. Bioinformatics

Department

Bioinformatics

College

College of Science & Mathematics

Advisor

Jason Heindl, Ph.D.

Committee Member 1

Benjamin Carone, Ph.D.

Committee Member 2

Jason Heindl. Ph.D.

Committee Member 3

Melissa Manners, Ph.D.

Disciplines

Bioinformatics | Life Sciences

Abstract

Agrobacterium tumefaciens is a soil-dwelling plant pathogen known for transferring DNA to host plants through a type IV secretion system. Central to its virulence and cellular regulation is the LysR-type transcriptional regulator, VtlR, which controls processes including biofilm formation, motility, tumorigensis, and small RNA expression. Although VtlR’s regulatory role is established, the specific functions of its conserved cysteine residues have only recently begun to be explored. This study investigates VtlR’s four cysteines (C144, C236, C244, and C273) through site-directed mutagenesis and a combination of phenotypic assays and transcriptional profiling. Phenotypic assays confirmed that C144 and C273 are important for proper VtlR control of multiple phenotypes. Transcriptomic analysis via RNA sequencing and differential gene expression profiling confirmed VtlR regulation of hundreds of genes, including many ABC transport systems and redox-sensitive pathways. Substitution of cysteine 144 with serine largely replicated results of a VtlR-null strain. These findings suggest that individual cysteine residues contribute differentially to VtlR function. Collectively, this work provides new insights into cysteine-mediated control of transcriptional networks in VtlR and highlights potential targets for modulating bacterial adaptation and virulence.

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