Enzyme · BEGINNER LESSON
M-MLV reverse transcriptase
M-MLV reverse transcriptase (RT) is a Moloney murine leukemia virus enzyme that makes DNA from an RNA template. It also has RNase H activity, which cuts the RNA strand in RNA-DNA hybrids.
What it is
M-MLV stands for Moloney murine leukemia virus. Its reverse transcriptase, often shortened to M-MLV RT, is a monomeric viral enzyme used as a tool in molecular biology. It is an RNA-dependent DNA polymerase, meaning it uses RNA as a template to build DNA. It also has RNase H activity, which means it can cut the RNA strand in an RNA-DNA hybrid. Sources also describe DNA-dependent DNA polymerase activity and terminal transferase activity, but its best-known role is copying RNA into complementary DNA (cDNA). [0,1]
[1] Substrate Recognition Governs Reverse Transcriptase ... - PMC [2] De novo binders overcome the MMLV RT stability-activity ...
How it works
The enzyme has two main parts: an N-terminal polymerase domain and a C-terminal RNase H domain. The polymerase region has finger, palm, and thumb subdomains that help it bind nucleic acids and synthesize DNA. In the viral life cycle, MLV reverse transcription happens in the cytoplasm. In the laboratory, the same chemistry is used to make cDNA for reverse transcription PCR (RT-PCR), gene cloning, gene expression analysis, and related methods. [0,1,2]
[1] Substrate Recognition Governs Reverse Transcriptase ... - PMC [2] De novo binders overcome the MMLV RT stability-activity ... [3] Epigenetic mechanisms of retroviral regulation: a comparative review
Mechanism and operating range
M-MLV RT works best at moderate temperatures, about 37–42 °C. The sources say higher temperature can inactivate it, and its low thermostability limits use at elevated temperatures. RNA structure and high guanine-cytosine (GC) content can also make primer binding and reverse transcription harder. The enzyme has relatively low processivity, so it may stop before making long cDNA products unless the reaction design is improved. It also lacks 3′-5′ exonuclease proofreading, so it has lower replication accuracy than many family B DNA polymerases. [0,1]
[1] Substrate Recognition Governs Reverse Transcriptase ... - PMC [2] De novo binders overcome the MMLV RT stability-activity ...
Limitations and engineered variants
The supplied sources emphasize trade-offs: improving stability can reduce activity, and vice versa. Engineered variants have been studied to improve thermostability, processivity, fidelity, and inhibitor resistance. One source reports that strengthened enzyme-nucleic acid interactions can improve resistance, while thermal stress can weaken productive complexes. Another source notes that stability improvements were tested in controlled in vitro conditions and still need confirmation in complex biological samples. [0,1]
[1] Substrate Recognition Governs Reverse Transcriptase ... - PMC [2] De novo binders overcome the MMLV RT stability-activity ...
SEE THE IDEA
M-MLV reverse transcriptase: from RNA template to cDNA
The starting nucleic acid that carries the sequence to be copied.
Uses the RNA template to synthesize DNA.
Removes the RNA strand from RNA-DNA hybrids.
The DNA copy used in laboratory workflows such as RT-PCR.
RNA template enters the polymerase domain, DNA is synthesized, and the RNase H domain can remove the paired RNA strand to support cDNA formation.
The enzyme couples DNA synthesis with RNA removal during reverse transcription.
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Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.