Name: how crispr remembers viral infections
Uploaded: 2025-06-12T09:30:40.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Biology

BIO.4

BIO.4.a

the-antiviral-system-of-bacteria-and-archaea-crispr

The Antiviral System of Bacteria and Archaea: CRISPR

Clustered Regularly Interspaced Short Palindromic Repeats - CRISPR fungiert zusammen mit CRISPR-assoziierten Cas-Proteinen als adaptives Immunsystem in Bakterien und Archaeen gegen Viren und fremde genetische Elemente. Sobald sich die virale DNA in der Zelle befindet, erkennen Cas-Proteine das Protospacer Adjacent Motif (PAM), entfernen das Protospacer-Segment aus dem viralen Genom und fügen es in das CRISPR-Array ein. Das CRISPR-Array speichert virale DNA-Fragmente als Abstandshalter zwischen palindromischen Wiederholungen und dient als genetisches Gedächtnis, um vergangene Infektionen zu erkennen. Das CRISPR-Array wird in prä-crRNA transkribiert, die sich mit tracrRNA paart. RNase III und Cas9 verarbeiten den Duplex zu crRNAs, die jeweils einen Spacer und Repeat-Fragmente tragen. Wenn sich das Virus erneut infiziert, sucht der Cas-crRNA-Komplex nach einer Übereinstimmung. Das Cas-Protein spaltet die virale DNA beim Abgleich und neutralisiert so die Infektion. Das PAM erhöht die Spezifität dieser Abwehr, indem es sicherstellt, dass Cas-Proteine nur auf fremde DNA abzielen und nicht auf das bakteriumseigene CRISPR-Array.

das antivirale system von bakterien und archaeen: crispr

CRISPR steht f&#252;r Clustered Regularly Interspaced Short Palindromic Repeats und ist ein adaptives Immunsystem, das in Bakterien und Archaeen vorkommt und sie vor Virusinfektionen sch&#252;tzt. Dieses System erm&#246;glicht es prokaryotischen Zellen, fremde genetische Elemente &#8211; vor allem Bakteriophagen &#8211; zu erkennen, sich an sie zu erinnern und sie zu neutralisieren, indem Fragmente der viralen DNA als genetisches Ged&#228;chtnis gespeichert werden.
Die CRISPR-Immunantwort beginnt w&#228;hrend einer Erstinfektion. Cas-Proteine (CRISPR-associated) spielen eine zentrale Rolle in diesem Abwehrmechanismus. Beim Erkennen fremder DNA &#8211; typischerweise viraler Herkunft &#8211; identifizieren Cas-Proteine bestimmte Sequenzen, die als Protospacer Adjacent Motifs (PAMs) bekannt sind. Diese Motive dienen als Marker zur Unterscheidung zwischen fremder und eigener DNA. Sobald ein PAM erkannt wird, schneidet der Cas-Komplex ein DNA-Segment des Eindringlings heraus &#8211; den sogenannten Protospacer &#8211; und integriert es in das Wirtsgenom innerhalb der CRISPR-Region. Diese Region besteht aus kurzen palindromischen Wiederholungen, die durch einzigartige Spacer aus fr&#252;heren Infektionen unterbrochen sind und so ein molekulares Archiv von Infektionen bilden.
Der CRISPR-Locus wird anschlie&#223;end in eine lange Vorl&#228;ufer-RNA, die pre-crRNA, transkribiert. Dieses Molek&#252;l wird durch RNase III und begleitende Cas-Proteine in kleinere CRISPR-RNAs (crRNAs) verarbeitet, wobei jede crRNA eine einzelne Spacer-Wiederholungs-Einheit enth&#228;lt. Diese crRNAs sind entscheidend f&#252;r die Steuerung der Immunantwort bei sp&#228;teren Infektionen.
Bei einer erneuten Infektion durch dasselbe Virus bildet die crRNA einen Komplex mit einem Cas-Protein &#8211; in vielen Systemen ist dies Cas9. Dieser crRNA-Cas-Komplex scannt die eindringende DNA nach einer Sequenz, die komplement&#228;r zum Spacer der crRNA ist. Wird eine &#220;bereinstimmung in der N&#228;he eines PAMs gefunden, spaltet das Cas-Protein die virale DNA an der Zielstelle und stoppt damit die Infektion. Die Notwendigkeit eines PAMs stellt sicher, dass das CRISPR-System nicht das eigene Genom des Wirts angreift und somit die zellul&#228;re Integrit&#228;t gewahrt bleibt.

Das antivirale System von Bakterien und Archaeen: CRISPR

CRISPR steht f&#252;r Clustered Regularly Interspaced Short Palindromic Repeats und ist ein adaptives Immunsystem, das in Bakterien und Archaeen vorkommt ...

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how crispr remembers viral infections

CRISPR is an adaptive immune system in bacteria and archaea that helps protect cells from viral infection. It works by identifying foreign genetic material, remembering it, and stopping the same invader later. In many cases, the main targets are bacteriophages, which are viruses that infect bacteria.

The first defense step begins during an initial infection. Cas proteins, which are CRISPR-associated proteins, detect foreign DNA by looking for specific sequences called Protospacer Adjacent Motifs, or PAMs. PAMs help Cas proteins tell invasive DNA apart from the cell’s own DNA. After recognition, the Cas complex removes a piece of the invader’s DNA called a protospacer and inserts it into the host genome.

That inserted DNA becomes part of the CRISPR array. The array contains short palindromic repeats with unique spacer sequences between them. Each spacer comes from a past invader, so the array acts like a genetic record of earlier infections.

The CRISPR locus is then transcribed into a long precursor RNA called pre-crRNA. RNase III and accessory Cas proteins process this RNA into shorter CRISPR RNAs, or crRNAs. Each crRNA contains one spacer-repeat unit and helps guide the immune response during future infections.

If the same virus infects the cell again, the crRNA joins with a Cas protein, often Cas9 in many systems. This complex scans the incoming DNA for a sequence that matches the crRNA spacer. When a match appears next to a PAM, the Cas protein cuts the viral DNA at that site and stops the infection. The PAM requirement also helps prevent the system from attacking the host’s own genome.

How CRISPR Remembers Viral Infections

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the antiviral system of bacteria and archaea: crispr

CRISPR is an adaptive immune system in bacteria and archaea that helps protect cells from viral infection. It works by identifying foreign genetic material, remembering it, and stopping the same invader later. In many cases, the main targets are bacteriophages, which are viruses that infect bacteria. The first defense step begins during an initial infection. Cas proteins, which are CRISPR-associated proteins, detect foreign DNA by looking for specific sequences called Protospacer Adjacent...

crispr/cas9 genome editing

CRISPR-Cas9 and DNA Repair in Cells

CRISPR-Cas9 uses a bacterial defense system to change DNA in cells. The CRISPR-Cas system first evolved in prokaryotes to protect bacteria from invading genetic material such as viruses and plasmids. Scientists later adapted it into a genome-editing tool for plants, animals, and humans. The key enzyme is Cas9, a DNA-cutting protein called an endonuclease from Streptococcus pyogenes. In the lab, a synthetic single guide RNA, or sgRNA, directs Cas9 to a chosen DNA site. The sgRNA matches the...

subviral agents

Viroids, Prions, and Satellite Viruses

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key terms and concepts

Learn how CRISPR stores viral DNA, makes crRNA guides, and uses Cas proteins to cut matching DNA during reinfection in bacteria and archaea.

How CRISPR Remembers Viral Infections | 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.

microbiology

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CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats is a adaptive immune system found in bacteria and archaea that protects ...

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BIO.4.e

How CRISPR Remembers Viral Infections

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