• Journal of Microbiology and Biotechnology
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• v.33 no.12
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• pp.1543-1551
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• 2023

The recently published high-resolution R388 T4SS structure provides exciting new details about the complete complex of T4SS, including the components making up the stalk and arches, numerous symmetry mismatches between regions of the complex, and an intriguing interpretation of the closed stalk and radial symmetry of the inner membrane complex, which is related to pilus biogenesis assembly. However, there are a few unidentified densities in the electron microscopy map and portions of the identified component sequences for which the structure is not yet known. It is also unclear how well this minimized DNA-transporting T4SS predicts the structure of other T4SSs, such as expanded systems and those that transport proteins rather than DNA. In this review, we evaluate what can be inferred from the recent high-resolution structure of the R388 T4SS with respect to the Cag and Dot/Icm systems. These systems were selected because, given what is currently known about these systems, we expect them to present most structural differences compared to the R388 T4SS structure. Furthermore, we discuss bacterial physiology and diversity, the T4SS structures and their variations between different bacterial species. These insights may prove beneficial for researchers who elucidate the structure and functions of T4SS in different bacterial species.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.126-132
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• 2009

Legionella spp. is the causative agent of Legionellosis, which induces a potentially fatal form of pneumonia. With a concentrated performance during the summer of 2008, we secured 73 isolates from the water systems of 25 wards in Seoul. We analysed serotypes, pathogenic genes (Dot/Icm), and patterns of pulsed-field gel electrophoresis (PFGE) in an attempt to confirm relationships among them. Different from the previous year's pattern (2007), among the isolates, 69 were Legionella pneumophila and 4 were Legionella spp. The serotype distribution of Legionella pneumophila was sg1 43, sg6 9, sg5 8, sg3 8, and sg2 1. The serotype for the 4 Legionella spp. was Legionella nautarum. Most of the Legionella pneumophila had several pathogenic genes. On the other hand, the 4 Legionella spp. were defective in pathogenicity in genomic terms. The PFGE patterns of the serotypes showed a tendency for diversity of Legionella pneumophila and a close correlation with genetic pathogenicity.