Related Experiment Video

Updated: May 28, 2026

High Resolution Electron Microscopy of the Helicobacter pylori Cag Type IV Secretion System Pili Produced in Varying Conditions of Iron Availability
09:05

High Resolution Electron Microscopy of the Helicobacter pylori Cag Type IV Secretion System Pili Produced in Varying Conditions of Iron Availability

Published on: November 21, 2014

Mitis group streptococci express variable pilus islet 2 pili

Dorothea Zähner1, Ashish R Gandhi, Hong Yi

  • 1Division of Infectious Diseases, Department of Medicine, Atlanta, Georgia, United States of America. dzahner@emory.edu

Plos One
|October 4, 2011
PubMed
Abstract

Insights

Pilus-islet 2 (PI-2) pili were identified in oral streptococci, revealing significant genetic diversity due to horizontal gene transfer. This pilus variation may explain differences in bacterial interactions and disease potential within this group.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Mitis group streptococci, including Streptococcus oralis, Streptococcus mitis, and Streptococcus sanguinis, are key players in oral biofilm formation, dental plaque, and infective endocarditis.
  • These bacteria engage in complex bacteria-bacteria and bacteria-host interactions.
  • The human pathogen Streptococcus pneumoniae utilizes pilus-islet 2 (PI-2) encoded pili for adhesion to host cells.

Purpose of the Study:

  • To investigate the presence and characteristics of PI-2 pili in Mitis group oral streptococci.
  • To explore the genetic diversity and evolutionary mechanisms, such as horizontal gene transfer, of PI-2 pili in these species.
  • To understand the potential role of PI-2 pili in the pathogenic traits of Mitis group streptococci.

Main Methods:

  • Identification and genetic analysis of PI-2 pilus-encoding islets in oral streptococci isolates.
  • Sequencing and comparative analysis of pitA and pitB genes, encoding structural pilus proteins.
  • Development of polyclonal antisera against PitA and PitB for immunodetection of pili.
  • Electron microscopy to visualize pilus structures.
  • Electronic multilocus sequence analysis for phylogenetic assessment.

Main Results:

  • PI-2 pilus-encoding genetic islets were found in specific isolates of S. oralis, S. mitis, and S. sanguinis, but not universally.
  • The identified PI-2 islets showed variations in pitA and pitB genes compared to S. pneumoniae, with multiple variants identified.
  • Evidence of intra- and interspecies horizontal gene transfer was indicated by species-independent combinations of pitA and pitB variants.
  • Electron microscopy confirmed the presence of pili on the bacterial surface, with lengths exceeding 700 nm.
  • Antiserum cross-reactivity suggested distinct interactions between pilus variants and antibodies.

Conclusions:

  • This study represents the first identification of PI-2 pili in Mitis group oral streptococci.
  • The findings highlight horizontal gene transfer as a significant driver of genetic diversity for PI-2 pili within these bacteria.
  • The observed diversity in PI-2 pili offers a potential link to strain-specific interactions, tissue tropisms, and pathogenic capabilities in Mitis group streptococci.

More Related Videos

Visualization of Twitching Motility and Characterization of the Role of the PilG in Xylella fastidiosa08:44

Visualization of Twitching Motility and Characterization of the Role of the PilG in Xylella fastidiosa

Published on: April 8, 2016

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility12:29

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility

Published on: March 11, 2022

Related Concept Videos

Fimbriae, Pili, and Axial Filaments01:28

Fimbriae, Pili, and Axial Filaments

Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
Cytoskeletal Proteins in Bacteria01:29

Cytoskeletal Proteins in Bacteria

Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
Bacterial Phylum Tenericutes01:24

Bacterial Phylum Tenericutes

The phylum Tenericutes, which includes the single class Mollicutes, comprises bacteria that lack cell walls. The term "Mollicutes" derives from the Latin word mollis, meaning "soft." These organisms are among the smallest known and are commonly referred to as mycoplasmas due to the prominence of the genus Mycoplasma, which includes well-known human pathogens. Despite their inability to stain gram-positively (a result of their lack of cell walls), mycoplasmas are phylogenetically related to the...
Surface Appendages of Archaea01:23

Surface Appendages of Archaea

Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, and motility. Among these appendages, pili and archaella stand out for their distinct morphologies and functionalities, enabling archaea to thrive in diverse and often extreme environments.Pili: Adhesion and Biofilm FormationPili are filamentous structures assembled from pilin protein subunits, primarily contributing to adhesion and biofilm...
Atypical Pneumonia01:14

Atypical Pneumonia

Atypical pneumonia, often caused by Mycoplasma pneumoniae, is a form of pulmonary infection that differs from the classical presentation of bacterial pneumonia in both its cause and clinical symptoms. Mycoplasma pneumoniae is a pleomorphic bacterium notable for its lack of a rigid cell wall. This structural characteristic imparts resistance to beta-lactam antibiotics and significantly influences the bacterium’s behavior within the human host.Other pathogens responsible for the disease include...
Bacterial Phylum Actinobacteria01:30

Bacterial Phylum Actinobacteria

Coryneform bacteria are gram-positive, aerobic, nonmotile rods that exhibit irregular, club-shaped, or V-shaped arrangements. Their V-shape results from snapping division, where the inner cell wall layer forms the cross-wall, while the outer layer remains intact until it ruptures on one side, causing the daughter cells to bend away.The primary genera are Corynebacterium and Arthrobacter. Corynebacterium includes diverse species, ranging from saprophytes to pathogens like Corynebacterium...