Name: archaeal pili and archaella in action
Uploaded: 2025-06-12T09:32:15.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Biology

BIO.4

BIO.4.c

Surface Appendages of Archaea

Archaeal surface appendages include pili and archaella, each playing distinct roles in adhesion, biofilm formation, and motility.Pili, similar in structure to type IV pili, are filamentous structures composed of pilin protein subunits and vital for adhesion and biofilm formation.Other surface structures, such as cannulae and hami, are highly specialized.Cannulae are hollow tubular structures observed in thermophilic archaea, such as Pyrodictium species. Their function is largely unknown, but they keep the daughter cells connected after division, creating a dense network of cells.Hami are attachment structures that resemble grappling hooks. They are used for strong adhesion to surfaces, resisting mechanical forces and stabilizing biofilms in extreme environments.Archaella are unique motility structures of archaea that are composed of multiple protein subunits and anchored in the cell envelope.The rotation of archaella is powered by ATP hydrolysis. It can rotate both clockwise and counterclockwise, driving the cell to move forward or in reverse directions.

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 formation. These structures enable archaea to anchor themselves to various surfaces, facilitating stable colonization in challenging habitats. Specialized variants of pili include cannulae and hami, which exhibit remarkable adaptations for specific ecological roles.Cannulae are hollow tubular structures observed in thermophilic archaea. They form intercellular connections between daughter cells post-division, creating a dense network that promotes cellular communication and stability within biofilms. In contrast, hami are unique hook-like appendages that exhibit a grappling hook morphology. These structures ensure robust adhesion to surfaces, providing resistance to mechanical forces and enhancing biofilm stability, particularly in extreme environmental conditions.In Saccharolobus solfataricus, two distinct types of pili have been identified, each serving unique purposes. The archaeal adhesive pilus (Aap) facilitates the attachment of cells to surfaces under particular growth conditions. On the other hand, the ultraviolet (UV)-inducible pilus (Ups) is specifically formed when cells are exposed to UV light. When UV radiation causes DNA damage, the Ups pili enable cells to aggregate, facilitating the transfer of genetic material between them. This process enhances DNA repair and promotes genetic exchange, which is crucial for adaptation and survival in challenging environments.Archaella: Unique Motility MechanismsArchaella are motility structures distinct from bacterial flagella, with significant differences in composition and function. Composed of multiple protein subunits and anchored in the cell envelope, archaella filaments are non-hollow, unlike their bacterial counterparts. The energy driving archaella rotation is derived from ATP hydrolysis rather than the proton motive force, highlighting archaea's unique energy utilization pathway. The ability of archaella to rotate in both clockwise and counterclockwise directions enables precise control over movement, allowing the cell to navigate forward or reverse effectively.These diverse surface appendages demonstrate the remarkable adaptability of archaea, supporting their survival and functionality across a wide range of ecological niches.

Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, ...

Education

JoVE Core

Microbiology

Unit

Microbial Cell Structure and Function        

KEY TERMS AND CONCEPTS

archaeal pili and archaella in action

Archaeal pili and archaella help archaea survive, attach, and move in challenging environments. These surface appendages support adhesion, biofilm formation, and motility. They give archaeal cells key advantages in habitats that can be extreme.

Pili are filament-like structures made from pilin protein subunits. Their main role is adhesion, which means helping cells stick to surfaces. They also support biofilm formation, where cells live in a shared, surface-attached community. Some pili are specialized. Cannulae are hollow tubes seen in thermophilic archaea, and they connect daughter cells after division. Hami are hook-like appendages with a grappling hook shape. They help cells cling tightly to surfaces and resist mechanical force.

In Saccharolobus solfataricus, two pili types have been identified. The archaeal adhesive pilus, or Aap, helps cells attach to surfaces under certain growth conditions. The ultraviolet-inducible pilus, or Ups, forms after UV light exposure. When UV radiation damages DNA, Ups pili help cells aggregate. This grouping can support genetic material transfer between cells. That exchange helps with DNA repair and adaptation.

Archaella are the motility structures of archaea. They are different from bacterial flagella in both composition and function. Archaella are built from multiple protein subunits and are anchored in the cell envelope. Unlike bacterial flagella, they are non-hollow. Their rotation is powered by ATP hydrolysis, not by the proton motive force. Archaella can rotate clockwise or counterclockwise, which helps cells move forward or reverse with control. Together, these appendages show how archaea use specialized surface structures to adapt to many ecological niches.

Archaeal Pili and Archaella in Action

prokaryotic vs. eukaryotic cells

Cell Organization in Prokaryotes and Eukaryotes

Prokaryotic and eukaryotic cells show two major patterns of cell organization. These differences shape the structure, size, and function of living things across the domains of life. Prokaryotic cells, such as bacteria and archaea, are simple in structure. They do not have a nucleus or other membrane-bound organelles. Their DNA is usually a single circular molecule found in the nucleoid region, which is not surrounded by a nuclear membrane. Prokaryotes are usually very small, about 0.1 to 5.0...

microbial morphologies 

Microbial Shapes and Cell Forms

Microbial shapes and cell forms help bacteria, archaea, and eukaryotic microbes survive in many environments. Cell shape affects how these organisms grow, take up nutrients, and handle waste. It also reflects the link between structure and function. Among bacteria, cocci and bacilli are the most common shapes. Cocci are spherical cells, and they may appear alone or in pairs called diplococci, chains called streptococci, clusters called staphylococci, or groups of four called tetrads. Bacilli...

bacterial cell wall 

Gram-Positive and Gram-Negative Walls

Bacterial cell walls give bacteria their shape and help protect them from osmotic stress. This rigid but flexible layer surrounds the plasma membrane and supports cellular integrity. Its main building block is peptidoglycan, a mesh-like polymer that adds strength while still allowing some flexibility. Peptidoglycan is made of alternating N-acetylglucosamine, or NAG, and N-acetylmuramic acid, or NAM. Short amino acid chains connect these sugar units and help form the strong network. The...

archaeal cell wall

Archaeal Cell Wall Types and Functions

Archaeal cell walls protect archaea and help them survive in extreme environments. Unlike bacterial cell walls, they do not have the peptidoglycan layer found in most bacteria. Instead, archaea use a range of materials, including proteins, polysaccharides, and pseudomurein, to build their outer layer. The most common archaeal cell wall is the S-layer, or surface layer. It is made of tightly packed protein or glycoprotein units that form a crystalline lattice. These repeating patterns can make...

peptidoglycan synthesis

Building the Bacterial Cell Wall

Peptidoglycan builds the bacterial cell wall and gives the cell its shape and strength. It is a mesh-like polymer around the bacterial plasma membrane. The polymer is made of repeating sugar units, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), linked by β-1,4 glycosidic bonds. Short peptide chains cross-link the sugar chains and make the wall more rigid. Peptidoglycan biosynthesis starts in the cytoplasm with soluble precursors. Uridine diphosphate, or UDP, binds to NAG and NAM to...

plasma membrane in bacteria and archaea

Bacterial vs Archaeal Membrane Lipids

Bacterial and archaeal plasma membranes control what enters and leaves the cell. They also help maintain cell integrity. Although both membranes do the same basic job, their structures are different because bacteria and archaea face different environmental demands. Bacterial plasma membranes are mainly made of phospholipids. These lipids have fatty acid chains linked to a glycerol backbone by ester bonds. They form a bilayer, with hydrophilic glycerol-phosphate heads facing outward and...

outer layers of the cell envelope

Capsules, Slime Layers, and S-Layers

Capsules, slime layers, and S-layers are outer coverings on prokaryotic cells. These layers help bacteria and archaea survive, attach to surfaces, and interact with their environment. They are often made of polysaccharides, polypeptides, proteins, or glycoproteins. Capsules are tightly bound and highly organized layers that stick firmly to the bacterial cell wall. They are usually made of polysaccharides, although some are made of polypeptides. A capsule protects cells from dehydration and can...

flagella and motility in bacteria

Bacterial Flagella as Tiny Rotary Motors

Bacterial flagella are thread-like structures that help cells move and respond to their surroundings. They extend from the cell envelope and support both motility and chemotaxis, which is the ability to move in response to chemical signals. Their design shows how bacteria use specialized structures to survive in different environments. A flagellum has three main parts: the filament, the hook, and the basal body. The filament is the long, helical part made of repeating flagellin protein...

fimbriae, pili, and axial filaments

How Bacteria Stick, Share Genes, and Move

Fimbriae, pili, and axial filaments are bacterial surface structures that help cells attach, exchange genes, and move. These hairlike appendages are made mainly of pilin protein. They support bacterial survival in different environments and can also increase pathogenicity. Fimbriae are fine, filament-like structures that are densely packed on the bacterial surface. They are about 2 to 10 nanometers wide and help bacteria attach to nonliving surfaces and to host tissues. This adhesion is an...

cell inclusions

Prokaryotic Cell Storage Inclusions

Prokaryotic cell storage inclusions help bacteria store nutrients, manage energy, and adapt to changing environments. These inclusions let cells survive when food, phosphate, sulfur, light, or oxygen levels change. They are important examples of how simple cells can still have highly specialized structures. Some inclusions store carbon. Poly-β-hydroxybutyric acid, or PHB, forms granules that act as a long-term carbon and energy reserve. Glycogen granules also store carbon, but they provide a...

endospores and sporulation

How Bacteria Survive with Endospores

Endospores help some bacteria survive harsh conditions. These dormant cells are made mainly by Gram-positive bacteria such as Bacillus and Clostridium. They are highly resistant to heat, ultraviolet and ionizing radiation, drying, and toxic chemicals. In rare cases, endospore-like structures have also been seen in some Gram-negative bacteria, including Coxiella burnetii and Sporosarcina ureae, as well as in other species exposed to extreme conditions. Sporulation begins when bacteria face...

nucleoid

How Prokaryotes Organize DNA

Prokaryotes organize their DNA in the nucleoid, a distinct region where genetic material and associated proteins are packed. Because prokaryotic cells do not have a membrane-bound nucleus, the nucleoid helps keep DNA organized and available for cell activities. In most bacteria and archaea, the DNA is a single, circular, double-stranded molecule that is tightly compacted by supercoiling and protein interactions. Nucleoid-associated proteins, or NAPs, help shape and maintain this DNA region.

Archaeal pili and archaella help archaea survive, attach, and move in challenging environments. These surface appendages support adhesion, biofilm formation, and motility. They give archaeal cells key advantages in habitats that can be extreme. Pili are filament-like structures made from pilin protein subunits. Their main role is adhesion, which means helping cells stick to surfaces. They also support biofilm formation, where cells live in a shared, surface-attached community. Some pili are...

key terms and concepts

Explore how archaeal pili help cells stick, form biofilms, and respond to UV stress, while archaella power movement in extreme environments.

Archaeal Pili and Archaella in Action | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

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Cell Inclusions

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Endospores and Sporulation

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Nucleoid

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BIO.4.e

Archaeal Pili and Archaella in Action

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