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Studies on Bacillus subtilis Penicillin-Binding Protein 4b

Li, Dongdong (2013) MOBM18 20131
Degree Projects in Molecular Biology
Popular Abstract
Exploration of the role of penicillin-binding protein 4b in Bacillus subtilis


The Gram positive bacterium Bacillus subtilis produces endospores which enable the bacterium to survive under extreme conditions, e.g. desiccation and extreme temperature. The cortex layer of the endospore is essential for heat resistance. It consists of modified peptidoglycan (PG), which is similar to PG in the cell wall of any bacterium. Class B penicillin-binding proteins (PBPs) participate in PG synthesis and contribute to determine the specific morphology of bacterial cells. B. subtilis has six genes encoding class B PBPs. The pbpI gene encodes PBP4b, which is a paralogue of SpoVD. SpoVD is only produced during sporulation and is required for endospore... (More)
Exploration of the role of penicillin-binding protein 4b in Bacillus subtilis


The Gram positive bacterium Bacillus subtilis produces endospores which enable the bacterium to survive under extreme conditions, e.g. desiccation and extreme temperature. The cortex layer of the endospore is essential for heat resistance. It consists of modified peptidoglycan (PG), which is similar to PG in the cell wall of any bacterium. Class B penicillin-binding proteins (PBPs) participate in PG synthesis and contribute to determine the specific morphology of bacterial cells. B. subtilis has six genes encoding class B PBPs. The pbpI gene encodes PBP4b, which is a paralogue of SpoVD. SpoVD is only produced during sporulation and is required for endospore cortex synthesis. It has been shown that deficiency in PBP4b has no apparent effect on spore PG. Till now the physiological role of PBP4b is unclear.

In this project, research was carried out to explore the role and subcellular localization of PBP4b in B. subtilis during sporulation. The PBP4b protein was produced in Escherichia coli and purified for biochemical analysis and production of polyclonal antibodies.

My work shows that PBP4b has a functional penicillin-binding transpeptidase domain. The protein is produced in sporulating B. subtilis cells and appears at the 3rd hour after the initiation of sporulation. Overproduction of PBP4b did not complement SpoVD-deficiency with regard to spore cortex synthesis. In addition, I optimized conditions for production of a soluble variant of PBP4b as a fusion protein with GST in E. coli.

Since few characters of the PBP4b protein are known, this study contributes to an understanding of the function of PBP4b in B. subtilis and similar bacteria. In further studies, the PBP4b antibody produced in this work can be used, for example, to trace PBP4b in different strains.

Advisor: Lars Hederstedt
Master´s Degree Project 30 credits in Microbiology 2013
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Li, Dongdong
supervisor
organization
course
MOBM18 20131
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
5425644
date added to LUP
2015-05-21 14:31:15
date last changed
2015-05-21 14:31:15
@misc{5425644,
  author       = {{Li, Dongdong}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Studies on Bacillus subtilis Penicillin-Binding Protein 4b}},
  year         = {{2013}},
}