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Updated: Jun 2, 2026
Live-Cell Fluorescence Microscopy to Investigate Subcellular Protein Localization and Cell Morphology Changes in Bacteria
Published on: November 23, 2019
Contribution of phosphoglucosamine mutase to determination of bacterial cell morphology in Streptococcus gordonii
Kisaki Shimazu1, Yukihiro Takahashi, Hiroyuki Karibe
1Department of Pediatric Dentistry, The Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda-ku, Tokyo, 102-8159, Japan. kisaki-s@tky.ndu.ac.jp
Abstract:
Phosphoglucosamine mutase (GlmM; EC 5.4.2.10) catalyzes the interconversion of glucosamine-6-phosphate to glucosamine-1-phosphate, an essential step in the biosynthetic pathway leading to the formation of the peptidoglycan precursor uridine 5'-diphospho-N-acetylglucosamine. We have recently identified the gene (glmM) encoding the enzyme of Streptococcus gordonii, an early colonizer on the human tooth and an important cause of infective endocarditis, and indicated that the glmM mutation in S. gordonii appears to influence bacterial cell growth, morphology, and sensitivity to penicillins. Moreover, the glmM mutation results in increased sensitivity to polymorphonuclear leukocyte (PMN)-dependent killing. In the present study, we observed similarities in the utilization of sugar between the wild-type strain and the glmM mutant of S. gordonii when cultivated with medium containing 0.2% glucose, fructose, lactose, or sucrose. Morphological analyses clearly indicated that the glmM mutation causes marked elongation of the streptococcal chains, enlargement of bacterial cells, increased distortion of the bacterial cell surface, and defects in cell separation. These results suggest that mutations in glmM appear to influence bacterial cell growth and morphology, independent of the carbon source.
Insights
Mutations in the phosphoglucosamine mutase (GlmM) gene of Streptococcus gordonii significantly alter bacterial cell morphology, causing chain elongation and cell enlargement. These changes occur independently of the carbon source utilized by the bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Phosphoglucosamine mutase (GlmM) is crucial for peptidoglycan precursor synthesis.
- Streptococcus gordonii is an oral bacterium linked to infective endocarditis.
- Previous studies indicated glmM mutations affect S. gordonii growth, morphology, and penicillin sensitivity.
Purpose of the Study:
- To investigate the impact of glmM mutations on Streptococcus gordonii morphology and cell growth.
- To determine if carbon source influences the morphological effects of glmM mutations.
Main Methods:
- Genetic manipulation to create a glmM mutant in S. gordonii.
- Cultivation of wild-type and mutant strains with various sugars (glucose, fructose, lactose, sucrose).
- Microscopic analysis of bacterial cell morphology and chain formation.
Main Results:
- The glmM mutation caused significant morphological changes, including cell elongation and enlarged cells.
- Defects in cell separation and distorted cell surfaces were observed in the mutant.
- These morphological alterations were consistent across different tested carbon sources.
Conclusions:
- The glmM gene plays a vital role in regulating Streptococcus gordonii cell shape and division.
- The observed morphological defects are independent of the bacterial carbon source.
- Understanding GlmM function is important for targeting S. gordonii pathogenesis.
