Related Experiment Video
Updated: May 15, 2025
13:07
Determining 3'-Termini and Sequences of Nascent Single-Stranded Viral DNA Molecules during HIV-1 Reverse Transcription in Infected Cells
Published on: January 30, 2019
9.2K
Structural basis of antiphage defense by an ATPase-associated reverse transcriptase.
Jerrin Thomas George1, Nathaniel Burman1, Royce A Wilkinson1
1Montana State University, Bozeman, Department of Microbiology and Cell Biology, Bozeman, Montana 59717, USA.
Biorxiv : the Preprint Server for Biology
|April 8, 2025
Summary
This study reveals reverse transcriptases (RTs) have dual roles in genetic parasite replication and cellular antiviral defense. Researchers elucidated the structure of a retron complex crucial for phage defense and viral replication arrest.
Area of Science:
- Molecular Biology
- Structural Biology
- Genetics
Background:
- Reverse transcriptases (RTs) are primarily known for their roles in retroviral replication.
- Emerging evidence indicates RTs also participate in cellular antiviral defense mechanisms.
Purpose of the Study:
- To determine the structure of a type I-A retron complex involved in phage defense.
- To elucidate the mechanism by which this retron complex mediates antiviral activity.
Main Methods:
- X-ray crystallography to determine the 3D structure of the retron complex.
- Biochemical assays to analyze the function of the retron complex components.
- In vitro assays to study the interaction between retron and phage-encoded factors.
Main Results:
- The 364 kDa retron complex comprises RNA, DNA, RT, HNH-nuclease, and SMC-family ATPase.
- Phage nucleases trigger retron-associated DNA degradation, leading to complex disassembly.
- Activated HNH nuclease cleaves tRNA, halting protein synthesis and viral replication.
Conclusions:
- Retrons exhibit paradoxical roles, contributing to both genetic parasite perpetuation and elimination.
- The structural and mechanistic insights provide a new understanding of RT functions in host-pathogen interactions.
Related Concept Videos
02:27DNA Base Pairing
26.6K
Erwin Chargaff’s rules on DNA equivalence paved the way for the discovery of base pairing in DNA. Chargaff’s rules state that in a double-stranded DNA molecule,
26.6K
00:56Viral Structure
61.3K
Viruses are extraordinarily diverse in shape and size, but they all have several structural features in common. All viruses have a core that contains a DNA- or RNA-based genome. The core is surrounded by a protective coat of proteins called the capsid. The capsid is composed of subunits called capsomeres. The capsid and genome-containing core are together known as the nucleocapsid.
61.3K
01:10Retrovirus Life Cycles
45.4K
Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the...
45.4K
01:30Lytic Cycle of Bacteriophages
69.9K
Bacteriophages, also known as phages, are specialized viruses that infect bacteria. A key characteristic of phages is their distinctive “head-tail” morphology. A phage begins the infection process (i.e., lytic cycle) by attaching to the outside of a bacterial cell. Attachment is accomplished via proteins in the phage tail that bind to specific receptor proteins on the outer surface of the bacterium. The tail injects the phage’s DNA genome into the bacterial cytoplasm. In the...
69.9K
02:33Retroviruses
12.1K
Retroviruses and retrotransposons both insert copies of their genetic elements into the genome of the host cell. Thus, the viral genes are passed on when the host genome is replicated or translated. A typical retroviral DNA sequence contains 3-4 genes that encode the different proteins required for its structural assembly and function as a molecular parasite. This DNA is transcribed into a single mRNA, which is very similar in structure to conventional mRNAs, i.e., it is capped at the 5’...
12.1K
02:53CRISPR and crRNAs
16.3K
Bacteria and archaea are susceptible to viral infections just like eukaryotes; therefore, they have developed a unique adaptive immune system to protect themselves. Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR-Cas) are present in more than 45% of known bacteria and 90% of known archaea.
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
16.3K