Biology subjects

Yoder, K. E.

Publications and source records attributed to Yoder, K. E..

4 recordsLinked to original sources

bioRxiv2022

Human immunodeficiency virus integration complexes are active following ordered addition of wild type integrase, viral DNA, and LEDGF/p75

Human immunodeficiency virus (HIV-1) requires integration of the viral genome into the host DNA for replication. Efficient HIV-1 integration employs a host co-factor LEDGF/p75 to stabilize the HIV-1 integration complex and tether that complex to host chromatin. Integration may be studied with purified components HIV-1 integrase (IN), LEDGF/p75, and DNA mimicking the ends of the viral DNA genome (vDNA) assembled as an intasome. There is a likely order of addition during infection with HIV-1 IN binding to vDNA before encountering LEDGF/p75. However, the ordered assembly of wild type HIV-1 IN, LEDGF/p75, and oligomer vDNA has not been tested. Variable assemblies occurred on ice before the addition of target DNA. Incubation on ice and addition of LEDGF/p75 were required to assemble complexes capable of efficient concerted integration. Integration efficiency following variable order of addition of intasome components was greatest when LEDGF/p75 was added last to preassembled HIV-1 IN and vDNA.

biochemistry↗

bioRxiv2021

The mouse mammary tumor virus intasome exhibits distinct dynamics on target DNA

Retroviral intasomes are complexes assembled from purified integrase (IN) and oligonucleotides mimicking viral DNA ends (vDNA). Recombinant intasomes faithfully recapitulate integration of vDNA into a target DNA. Structural studies of retroviral intasomes have revealed an array of IN oligomer forms, which appear to share a conserved intasome core coordinating the vDNA ends for strand transfer into the target DNA. Here we have explored the biochemical and dynamic properties of the mouse mammary tumor virus (MMTV) octameric intasome. We show that the MMTV intasome is remarkably stable compared to the prototype foamy virus (PFV) tetrameric intasome. MMTV integration activity peaks within the range of physiological ionic strength and is more active in the presence of manganese compared to magnesium. Single-molecule images demonstrate that the target DNA search by MMTV intasomes appears rate-limiting, similar to PFV intasomes. The time between strand transfer of the two MMTV vDNA ends into the target DNA is [~]3 fold slower than PFV intasomes. MMTV intasomes can form extremely stable, largely immobile filaments on a target DNA that are comprised of multiple intasomes. This unusual property suggests that MMTV intasomes may readily form higher order oligomers that might underpin their increased stability.

biochemistry↗

bioRxiv2021

DNA Breaks and Gaps Target Retroviral Integration

Integration into a host genome is essential for retrovirus infection and is catalyzed by a nucleoprotein complex (Intasome) containing the viral integrase (IN) and reverse transcribed (RT) copy DNA (cDNA). Previous studies demonstrated DNA site recognition limited intasome integration. Using single molecule Forster resonance energy transfer (smFRET), we show Prototype Foamy Virus (PFV) intasomes pause at DNA strand breaks and gaps. The break/gap discontinuities are similar to base excision repair (BER) lesion-processing intermediates, which affect retrovirus integration in vivo. Pausing targeted site-directed integration at the break/gap without inducing intasome conformational alterations. An 8-oxo-guanine lesion normally processes by BER and a G/T mismatch or a +T nucleotide insertion that induce flexibility or a bend in the DNA backbone did not promote intasome pausing or targeted integration. These results suggest that repair intermediates can modulate dynamic intasome-DNA interactions which target retroviral integration.

biochemistry↗

bioRxiv2021

Among retroviral integrases prototype foamy virus integrase displays unique biochemical activities

Integrase enzymes of different retroviruses assemble as functional complexes with varying multimers of the protein. Retroviral integrases require a divalent metal cation to perform one-step transesterification catalysis. Tetrameric prototype foamy virus (PFV) intasomes assembled from purified integrase and viral DNA oligonucleotides were characterized for their activity in the presence of different cations. While most retroviral integrases are inactive in calcium, PFV intasomes appear to be uniquely capable of catalysis in calcium. The PFV intasomes also contrast other retroviral integrases by displaying an inverse correlation of activity with increasing manganese beginning at relatively low concentrations. The intasomes were found to be significantly more active in the presence of chloride co-ions compared to acetate. While HIV-1 integrase appears to commit to a target DNA within 20 seconds, PFV intasomes do not commit to target DNA during their reaction lifetime. Together these data highlight the unique biochemical activities of PFV integrase compared to other retroviral integrases.

biochemistry↗