Electron Microscopic Observations of Cell Division in Mycobacterium vaccae V1

Takade, Akemi; Takeya, Kenji; Taniguchi, Hatsumi; Mizuguchi, Yasuo

doi:10.1099/00221287-129-7-2315

Cited by 25 publications

(36 citation statements)

References 10 publications

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“…S2 in the supplemental material). As in these three species, the formation of a complete septal partition, either straight, diagonal, or curved, prior to constriction had been observed in cell division studies on M. lepraemurium (18), M. smegmatis (1), M. leprae (10,33), M. vaccae (32), M. avium (26), and several other mycobacterial species (19). Similarly, septal constriction was also initiated by the OL in an identical manner, by growing and invaginating into the S-ETL, in all three species.…”

Section: Resultsmentioning

confidence: 78%

“…ously (32). In brief, the cells were fixed in 1% (vol/vol) osmium tetroxide buffered with 0.15 M cacodylate buffer (pH 7.2) for 1 h at room temperature, washed once with the same buffer, and postfixed for 2 h at room temperature in 0.15 M cacodylate buffer (pH 7.2) containing 2% (wt/vol) tannic acid (to stain the outermost layer, with background staining with lead citrate) and 2% (vol/vol) glutaraldehyde.…”

Section: Bacterialmentioning

confidence: 99%

“…Studies on mycobacterial cell division (reviewed in reference 14) using transmission electron microscopy (TEM) for Mycobacterium lepraemurium (18), M. leprae (10,15), Mycobacterium avium (26), and M. vaccae (32) showed the formation of a complete septal partition during cell division, followed by constriction to generate two daughter cells. Transmission and scanning electron microscopic studies on Mycobacterium vaccae (32) and M. tuberculosis (9) cells, and fluorescence microscopic studies on M. smegmatis and M. tuberculosis (34), showed the presence of low proportions of "V"-shaped cells during the final stages of division. Similar "V"-shaped cells had been observed previously for Arthrobacter atrocyaneus (31) and Arthrobacter crystallopoietes (20), but in higher proportions.…”

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Unveiling Unusual Features of Formation of Septal Partition and Constriction in Mycobacteria—an Ultrastructural Study

2012

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The ultrastructural functions of the electron-dense glycopeptidolipid-containing outermost layer (OL), the arabinogalactanmycolic acid-containing electron-transparent layer (ETL), and the electron-dense peptidoglycan layer (PGL) of the mycobacterial cell wall in septal growth and constriction are not clear. Therefore, using transmission electron microscopy, we studied the participation of the three layers in septal growth and constriction in the fast-growing saprophytic species Mycobacterium smegmatis and the slow-growing pathogenic species Mycobacterium xenopi and Mycobacterium tuberculosis in order to document the processes in a comprehensive and comparative manner and to find out whether the processes are conserved across different mycobacterial species. A complete septal partition is formed first by the fresh synthesis of the septal PGL (S-PGL) and septal ETL (S-ETL) from the envelope PGL (E-PGL) in M. smegmatis and M. xenopi. The S-ETL is not continuous with the envelope ETL (E-ETL) due to the presence of the E-PGL between them. The E-PGL disappears, and the S-ETL becomes continuous with the E-ETL, when the OL begins to grow and invaginate into the S-ETL for constriction. However, in M. tuberculosis, the S-PGL and S-ETL grow from the E-PGL and E-ETL, respectively, without a separation between the E-ETL and S-ETL by the E-PGL, in contrast to the process in M. smegmatis and M. xenopi. Subsequent growth and invagination of the OL into the S-ETL of the septal partition initiates and completes septal constriction in M. tuberculosis. A model for the conserved sequential process of mycobacterial septation, in which the formation of a complete septal partition is followed by constriction, is presented. The probable physiological significance of the process is discussed. The ultrastructural features of septation and constriction in mycobacteria are unusually different from those in the well-studied organisms Escherichia coli and Bacillus subtilis.T he presence of a bilayered plasma membrane and a triplelayered cell wall, constituted by an electron-dense outermost layer (OL) containing mostly glycopeptidolipids (11, 37), an electron-transparent layer (ETL) below, consisting of an arabinogalactan-mycolic acid complex (22,36), and an electrondense peptidoglycan layer (PGL), has been observed and characterized through ultrastructural and biochemical studies in Mycobacterium smegmatis (7,12,16,27), Mycobacterium xenopi and other mycobacterial species (reviewed in references 2, 17, 24, and 27), Mycobacterium tuberculosis (3, 9, 33; reviewed in reference 5), Mycobacterium leprae (33), and Mycobacterium kansasii (25,27). Numerous studies had been carried out on the ultrastructures of the OL, ETL, and PGL, their molecular compositions, and the probable roles of these layers in the physiology, pathology, and virulence of different mycobacterial species (6-8; reviewed in references 3 and 5). However, the functional roles of these layers in cell division remained unclear. Studies on mycobacterial cell division (reviewed in refe...

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Section: Resultsmentioning

confidence: 78%

Section: Bacterialmentioning

confidence: 99%

mentioning

confidence: 99%

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Unveiling Unusual Features of Formation of Septal Partition and Constriction in Mycobacteria—an Ultrastructural Study

2012

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“…Mycobacteria are known to form a V shape during the late stages of cell division (397), as shown more recently in outstanding micrographs (85). These V-shaped bacteria were found to have nascent PG deposited at the poles and the exterior side of the V (404).…”

Section: What Is the V-snapping Process Of Dividing Mycobacteria?mentioning

confidence: 85%

“…When the cell divides by hydrolyzing the PG linking the daughter cells together, the outer layers are still intertwined. The V-shaped splitting of cells results from an uneven snapping, or rupturing, of these outer layers (397,404). This rupturing of outer material could also be aggravated polar growth occurring from the newly formed septum prior to completion of cell division (115).…”

Section: What Is the V-snapping Process Of Dividing Mycobacteria?mentioning

confidence: 99%

Bacterial Growth and Cell Division: a Mycobacterial Perspective

Hett

Rubín

2008

Microbiol Mol Biol Rev

342

293

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SUMMARY The genus Mycobacterium is best known for its two major pathogenic species, M. tuberculosis and M. leprae, the causative agents of two of the world's oldest diseases, tuberculosis and leprosy, respectively. M. tuberculosis kills approximately two million people each year and is thought to latently infect one-third of the world's population. One of the most remarkable features of the nonsporulating M. tuberculosis is its ability to remain dormant within an individual for decades before reactivating into active tuberculosis. Thus, control of cell division is a critical part of the disease. The mycobacterial cell wall has unique characteristics and is impermeable to a number of compounds, a feature in part responsible for inherent resistance to numerous drugs. The complexity of the cell wall represents a challenge to the organism, requiring specialized mechanisms to allow cell division to occur. Besides these mycobacterial specializations, all bacteria face some common challenges when they divide. First, they must maintain their normal architecture during and after cell division. In the case of mycobacteria, that means synthesizing the many layers of complex cell wall and maintaining their rod shape. Second, they need to coordinate synthesis and breakdown of cell wall components to maintain integrity throughout division. Finally, they need to regulate cell division in response to environmental stimuli. Here we discuss these challenges and the mechanisms that mycobacteria employ to meet them. Because these organisms are difficult to study, in many cases we extrapolate from information known for gram-negative bacteria or more closely related GC-rich gram-positive organisms.

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The structure of pili under electron and atomic force microscopy

Farnia,

Ghanavi

et al. 2024

Pili in Mycobacterium Tuberculosis

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Electron Microscopic Observations of Cell Division in Mycobacterium vaccae V1

Cited by 25 publications

References 10 publications

Unveiling Unusual Features of Formation of Septal Partition and Constriction in Mycobacteria—an Ultrastructural Study

Unveiling Unusual Features of Formation of Septal Partition and Constriction in Mycobacteria—an Ultrastructural Study

Bacterial Growth and Cell Division: a Mycobacterial Perspective

The structure of pili under electron and atomic force microscopy

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