Defense Date

8-11-2006

Graduation Date

2006

Availability

Immediate Access

Submission Type

dissertation

Degree Name

PhD

Department

Biological Sciences

School

Bayer School of Natural and Environmental Sciences

Committee Chair

Joseph R. McCormick

Committee Member

David Lampe

Committee Member

Nancy Trun

Committee Member

Valerie Oke

Keywords

cell division, streptomyces, cytokinesis, differentiation, sporulation, transposon

Abstract

Here I describe both molecular and classical genetic approaches to the study of prokaryotic cell division. I detail the characterization of four cell division gene homologues: ftsL, divIC, ftsW and ftsI. FtsI, a penicillin-binding protein and transpeptidase involved specifically in septal peptidoglycan biosynthesis, is the only protein product of these four genes with a known role during cell division. I show that a null-mutation in any of the four genes resulted in a mutant with a medium-dependent division phenotype that was more severe on a rich medium. In E. coli, B. subtilis and other bacteria, these genes are essential, but in S. coelicolor they are only required for efficient division. Using phase-contrast and transmission electron microscopy, I was able to propose a role in cell division for FtsL and DivIC. In addition, I describe the development of a high efficiency, Tn5-based in vivo transposon system for the random insertional mutagenesis of Streptomyces coelicolor. This method allows high throughput screening of insertion mutants to identify novel genes involved in a variety of cellular processes. Because cell division is only required for spore formation in Streptomyces, new cell division genes can be identified by transposon mutagenesis, a strategy that would not be possible in other organisms. I have successfully conducted screens to identify transposon insertions in known developmental genes, and have also partially characterized a mutant with an interesting developmental phenotype. This mutant possessed a transposon insertion in a gene of previously unknown function, and displayed a spore shape and size defect upon examination with phase-contrast and transmission electron microscopy. Thus, I describe two different approaches to elucidate the process of cell division in S. coelicolor and other bacteria.

Format

PDF

Language

English

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